Queen's Botanist in Scotland, Professor of Botany in the University and Keeper of the Royal Botanic Garden, Edinburgh

O;cfor�

AT THE CLARENDON PRESS

PRINTED AT THE CLARENDON PRESS

PREFACE

The object of this work is to give such an account of palaeophytology shall meet the special requirements of the botanist, and it can scarcelynbsp;necessary to offer a detailed or lengthy plea in justification of my undertaking. Botany, which in former times generally treated palaeophytologynbsp;a very step-motherly manner, now finds it to be a subject of the highestnbsp;interest to herself on account of the prominence at present assumed by thenbsp;point of view of the theory of descent. But it is no easy task to obtainnbsp;3- general view of such results of palaeophytological researches as arenbsp;botanically useful; for, owing to the inconceivably fragmentary conditionnbsp;of the literature and the urgent necessity for submitting it to manifold andnbsp;searching criticism, the accomplishment of this task inevitably means thenbsp;devotion to it of years of work, and few professed botanists have this timenbsp;to give to it. And if our present text-books do not succeed in giving usnbsp;such a view, this is chiefly due to the fact that they are all more or lessnbsp;endeavouring to serve two masters, palaeontology and botany, and in thisnbsp;endeavour it is botany which as a rule comes worst off. It is hardlynbsp;possible rightly to preserve unity of presentation in a book in which equalnbsp;justice ought to be done to several points of view. Therefore the presentnbsp;Account of palaeophytology, which may itself appear to some readers to benbsp;rather one-sided, may be allowed to step in as supplying an existing want.nbsp;It is a first attempt in the direction indicated, and as such it has manynbsp;defects which are certainly thoroughly well known to the author himself, andnbsp;which he begs may not be judged too severely.

The work here offered to the general public has gradually grown up out of University Lectures delivered by me. in Gottingen at three differentnbsp;times in the course of the last six years. I had at first intended to preserve the lecture-form, but ultimately found that this was unsuitable andnbsp;must be abandoned. Then came the difficulty of finding a proper title.

The book could not be called simply � Palaeophytology,� since it does not take in the whole of the subject. The reasons why it omits thenbsp;Angiosperms and confines itself to the consideration of the Thallophytes,nbsp;Archegoniatae, and Gymnosperms will be found in the introductorynbsp;chapter. And if I have at length decided to call it an � Introductionnbsp;to Palaeophytology,� this title is after all only a way of getting out ofnbsp;a difficulty, for it requires that the word palaeophytology should benbsp;understood in a narrower and more botanical sense, and .should mean thenbsp;doctrine of the old types of vegetable forms as distinguished from thenbsp;Angiosperms, which made their appearance in later times and introducednbsp;the modern era. It is in this sense only that the title and the contentsnbsp;correspond to one another.

In choosing the woodcuts I have contented myself with those which were most necessary. For figures of the countless extant remains of plantsnbsp;the reader must have recourse, where they are not already known to him,nbsp;to the �Paleontologie v�g�tale� of W. Ph. Schimper, to Zittel�s �Handbuchnbsp;der Palaontologie,� and to Renault�s � Cours de botanique fossile.� It isnbsp;impossible to give a figure of every object, and I have therefore limitednbsp;myself for the most part to the representation of those which are of thenbsp;greatest interest to the botanist. The larger part of the woodcuts are new,nbsp;and are from drawings by Herr O. Peters, which were traced on the blocknbsp;itself. I have especially to thank Herr Hofrath Schenk of Leipsic for verynbsp;kindly granting me the use of some figures from the volume of Zittel�snbsp;Handbuch which deals with plants.

The mastering of the literature was, as I have said, one of the chief difficulties encountered in the composition of this book. I have done mynbsp;best to overcome this difficulty, and I trust that I have taken into consideration the most important of the publications which have appeared upnbsp;to the end of the year 1886; still there may be some which I have overlooked. Among later works I have been able to refer, at least for thenbsp;most essential points, only to W. C. Williamson�s monograph of Stigmarianbsp;ficoides; this I could not have done but for the courtesy of the author,nbsp;who supplied me with proofs of the tables of figures before the work wasnbsp;published.

In order to avoid frequent repetitions of the citations, a list of the literature has been compiled and placed at the end of the volume, arrangednbsp;in the alphabetical order of the authors� names. For the benefit of the lessnbsp;experienced reader the titles of the most important works are distinguishednbsp;from the rest by being printed in italics,

It would have been quite impossible for me to have formed an independent judgment on opposing views in regard to many and those precisely the most important points, if opportunity had not been given me in thenbsp;kindest manner in very various quarters of studying a number of originalnbsp;specimens and original sections of great value. I here express my heartynbsp;thanks to the many persons who have aided me in this manner. I amnbsp;especially indebted to Dr. W. C. Williamson of Manchester, who gave menbsp;facilities for studying the treasures of his collection ; to Drs. W. Carruthersnbsp;and Woodward of London, to whom I owe my knowledge of the materialsnbsp;in the British Museum, and especially of the collection of sections preservednbsp;in that institution and of the treasures bequeathed to it by R. Brown; tonbsp;Renault of Paris, who assisted me in my examination of the collectionsnbsp;in the Paris Museum, and was himself kind enough to explain to me thenbsp;niost important of his preparations; and to F. Romer of Breslau, who wasnbsp;never weary of supplying me with original specimens from Goppert�s collection. Without the friendly help which I received from these labourers innbsp;the science, I should never have succeeded in doing any justice to the subjectnbsp;of my book.

PREFACE TO THE ENGLISH EDITION

This translation of Count Solms-Laubach�s Introduction to Fossil Botany brings within reach of English readers the only critical digestnbsp;as yet published of our present knowledge of Fossil Plants from the pointnbsp;of view of Botanical Morphology, and is an important addition to thenbsp;series of standard botanical works issued by the Clarendon Press.

I have to thank the author for help in several points concerning the translation, and with his consent some corrections of statement have beennbsp;made in the English text. To Professor W. C. Williamson I am indebtednbsp;for some of these, and I have to acknowledge aid in the rendering ofnbsp;geological terminology and nomenclature from Dr. Archibald Geikie andnbsp;Professor F. Rudler.

c: o N T E N T S

131

132 142nbsp;150nbsp;152

154

157

158 160nbsp;165

175

186

194

198

199

200 203nbsp;205nbsp;205nbsp;210nbsp;213nbsp;215nbsp;232

241

242

247

248

249 251nbsp;260

263

268

269

270 27s

280

287

291

293

294

296

307

316

IX. nbsp;nbsp;nbsp;Lycopodites, Ptilophyton, Psilotites, Psilophyton, Iso�tites

Attempts to reconstruct its course of development ..... Cyclostigma, Arthrostigma .........

CONTENTS.

Specimens showing fructifications and stems in conjunction Justification of the division of Calamariae into archegoniate Calamitae andnbsp;gymnospermous Calamodendraenbsp;Sphenophylleae ....

XV. nbsp;nbsp;nbsp;Remains of stems of doubtful affinity, in which the character of the

outer surface is unknown Sigillariopsisnbsp;Poroxylonnbsp;Lyginodendronnbsp;Heterangium .

XVI. nbsp;nbsp;nbsp;Remains of plants of doubtful affinity, in which the character of

PAGE

320

322

324

338

340

343

345

351

353

355

356 358

362

363 363

365

366

367 369nbsp;369

373

ERRATA

Page 56, lines 13 and 15, for Pinites read Finns ,,nbsp;nbsp;nbsp;nbsp;57, line 7 from bottom,yigt;/-Abies Abietites

16 from bottom, Cycadostrobus read Cycadeostrobus ,, from bottom, Brunoni read Brunonisnbsp;2 of Explanation of Fig. i,for rise read rises

I of Explanation of Fig. 7, for angulostriatus read angulosostriatus 16 from bottom, for angulostriatus read angulosostriatusnbsp;18, for Ouandongianum read Ouangondianumnbsp;7 from bottom, for Gopp.�, read Gopp.�

133, nbsp;nbsp;nbsp;line 22, for rachis read rhachisnbsp;� ,t ^3; fi�' rachides read rhachides

6, for Letten Kohl read Lettenkohl I, for Autunensis read autunensisnbsp;20, for Zwickauiense read zwickauiensenbsp;,, 15, for Whitbyense read whitbyense

� II from bottom, yur pentarc read pentarch and for hexarc read hexarch �nbsp;nbsp;nbsp;nbsp;3 A'' Zippe read Zippea

,, last line, A'' Oppoliense read oppoliense 175, heading of Chapter,A'' Marsilioideae read Marsileoideaenbsp;214, line 3 from bottom. A''the they were furnished withnbsp;352,nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;6 from bottom,A^' inflorescence rrurf fructification

PALAEOPHYTOLOGY.

INTRODUCTION.

The subject of palaeophytology admits of very different modes of ^^�eatment; the points of view of the geologist are not those of the botanist,nbsp;the botanist looks at the remains which have come down to us innbsp;succession of geological formations with different eyes, according asnbsp;purpose for which he examines them gives greater prominence tonbsp;interests of pure classification or of the geography of plants, ofnbsp;Phylogeny or of physiology. On the other hand, a connected account ofnbsp;those results of palaeophytology which are of use to the botanist oughtnbsp;^^rtainly to do justice to all these points of view. But the longer I occupiednbsp;Myself with the subject, the more clearly I perceived that this is at presentnbsp;attended with almost insuperable difficulties, at all events that I was not innbsp;^ position to grapple successfully with the task. The systemati.st, whosenbsp;'Jsiness it is to submit to constant critical examination the results whichnbsp;^^0 Palaeophytologists have been able to establish with regard to extinctnbsp;PUnt-types, has no need of exact descriptions of the forms, whose nearestnbsp;Relatives are within his reach at any moment in their living state for thenbsp;determination of his bearings in every direction; fossil Angiospermsnbsp;^^Pecially at least in the form in which they can at present be set beforenbsp;j nave only the very smallest value for his purposes; his interest cul-^inates in the remains which we possess from remote epochs in the development of our globe. On the other hand, it is just with these remains thatnbsp;� student of the geography of plants and of phylogeny can do littlenbsp;iiothing; he must go backwards step by step from living plants whichnbsp;exactly known to him in all their parts in order to find firm groundnbsp;�' his investigations ; objects, such as the fossil leaves of oaks and chestnuts,nbsp;''^Uch are matter of indifference to the systematist, are exactly the thingsnbsp;'''hich interest him most.

th nbsp;nbsp;nbsp;evident that with the advance in knowledge which may be expected

kingdom have been traced back to the old formations, and the genetic relations of extinct groups to those now existing and to their progenitorsnbsp;have been discovered. The filiation has actually been already traced a longnbsp;way backwards in the case of single genera or cycles of affinity, and resultsnbsp;have been obtained by Heer ^ in the case of the Salisburieae, and in that ofnbsp;the Gymnosperms generally by the incomparable works of Grand� Eury ^nbsp;and Renault� on Cordaites, which are invaluable as aids to phylogeneticnbsp;determinations.

But though the way has been thus clearly pointed out for palaeophy-tological research in various directions, yet it follows from what has been said that it is at present necessary to keep the different points of viewnbsp;distinctly separate from one another. Hence it is that the present worknbsp;is strictly confined to the stand-point of the systematise being intended tonbsp;show to botanists in a perspicuous form and after application of the necessary criticism to what extent the efforts of palaeophytologists have furtherednbsp;the completion of the Natural System. It will be advisable that thenbsp;systematic treatment of the material should be preceded by a short exposition of the methods of palaeophytological research as well as by a noticenbsp;of the mode of preservation of fossil remains, notwithstanding that thenbsp;greater part of what can be said on these points will be found set forth in anbsp;masterly manner in Unger�s work'^.

Since fossil plants reached the place of their deposit in almost all cases in comparatively small fragments, the first object always is to determinenbsp;the manner in which these fragments, these branches, leaves, fruits, belongednbsp;to one another. It would be a similar task to reconstruct a forest from thenbsp;mud of a piece of water into which the dead parts of the trees have fallen.nbsp;In these circumstances we can only certainly conclude that separate partsnbsp;belong to one another in two cases : first, if they occur once and exceptionally in union with one another ; secondly, if they exactly resemble onenbsp;another in characteristic features of anatomical structure. Simple as thisnbsp;appears at first sight, yet various circumstances occur in practice to makenbsp;the very greatest circumspection necessary in applying both these criteria.nbsp;In the case of a specimen showing parts in connection with one anothernbsp;which are usually separate, since we are dealing in most cases with impressions of plants, we have to make quite sure in each several instance thatnbsp;there is no third formless object lying over two distinct but convergingnbsp;remains in such a manner as to bring about an apparent connection betweennbsp;them. Mistakes have as a matter of fact often arisen in this manner. Withnbsp;regard to the establishing the anatomical identity of two separate fragments,nbsp;it mu.st be remembered that this presupposes an exact knowledge of the

atoiny, for without this it is impossible to determine, the value of the points of anatomical comparison which have been observed.

nil cases in which neither of these two criteria could be obtained, th '^P^y^�^ogists have preferred to make use of conclusions drawn fromnbsp;le frequent or constant occurrence of the parts together in their places ofnbsp;posit. Conclusions of this kind have been largely employed by Brong-^'art and Goldenberg, and also bySchimper, It cannot be denied that theynbsp;Way be resorted to in certain cases, but only where they are accompaniednbsp;y various indications of probability. In all other cases this method ofnbsp;Pioofis not only dangerous, but is absolutely to be rejected. To see this,nbsp;^0 have only to reflect that in this way we might distinctly conclude fromnbsp;� detached fossil remains of a forest composed of Podocarpus and larch,nbsp;3-t the leaves of the one and the cones of the other genus belonged to onenbsp;3-ttother, because being the more durable parts they lay there in largenbsp;quantities, while the needles of the larch had rotted away and disappeared,nbsp;und the seeds of Podocarpus if present at all had been crushed into shapelessness. It has been particularly unfortunate that authors in adoptingnbsp;Ihis method have very commonly neglected to state the proofs on whichnbsp;'�^ey have founded their identifications, so that we remain in many casesnbsp;^f the kind in great doubt as to their value, and are often compelled tonbsp;have recourse to tedious critical investigations.

The fullest accounts of the mode of preservation of fossil remains of plants will be found in Unger in G�ppert in many places, and innbsp;Schimper^. Two essentially different cases must be distinguished ; thesenbsp;have been known since G�ppert�s� time as true petrifaction and as incrustation. To certain other cases intermediate between these two we shall recurnbsp;a future page.

The characteristic mark of true petrifaction is that the remains of the plant are thoroughly permeated by the petrifying substance. This may benbsp;amorphous or distinctly crystalline, and in the latter case the plant is simplynbsp;riaversed by the cleavage-surfaces. The effect is usually very beautiful,nbsp;^specially in petrifactions in the carbonates. If the petrifying substance isnbsp;lernoved by suitable solvents, there remains behind an organic body usuallynbsp;pf small size, which originates in the inclosed fossil and shows its form, andnbsp;mostly brown or black, but in a few cases displays an approach to thenbsp;^'^iginal colour. G�ppert� made many experiments in the dissolution ofnbsp;��ils, and even believes that he obtained cellulose-reaction in residua of

Very various bodies occur in nature as agents of petrifaction. Among silicic acid has the first claim to mention here in the form both of opal

and of chalcedony. It is the one of all others which ensures the most perfect preservation of the enclosed remains. Silicified woods are found in extraordinary quantity in all formations ; it is more rare to find the morenbsp;delicate parts of plants, leaves, seeds, or the fructifications of ferns wellnbsp;preserved in the silicified state. Specimens of the latter kind occurnbsp;chiefly in the hornstones of the Rothliegende at Chemnitz and in thenbsp;Plauensche Grund near Dresden, in the same formation at Autun, and in thenbsp;siliceous fragments of Grand� Croix near St. �tienne, which represent anbsp;fossil forest. These pebbles, which belong to the uppermost beds of thenbsp;Carboniferous and supplied Renault with the principal material for hisnbsp;admirable researches, will be discussed again at greater length in anbsp;succeeding page.

The next in order of importance are the isomorphous carbonates of calcium, magnesium, and iron, CA CO^, CA CO^ Mg CO^, Fe COo. Gop-pert is of opinion that calcium carbonate is present in some petrifactions innbsp;the form of arragonite ; it occurs in most cases as calc-spar. Here too thenbsp;remains of plants may in certain circumstances be in an excellent state ofnbsp;preservation. This kind of petrifaction is found in great abundance in thenbsp;Coal-measures of England and of the district of the Ruhr. It occurs also innbsp;North America in the State of Missouri, but the remains, so far as I know, arenbsp;still undescribed. I have seen two fragments in F. R�mer�s collection, butnbsp;unfortunately the place where they were found is not distinctly stated.nbsp;Their surface resembles that of the Stigmarias, and transverse sectionsnbsp;show that they contain a confused mass of fragments of Stigmarias andnbsp;of leaf-stalks of Ferns in different states of preservation. Petrifactionsnbsp;in carbonate of iron very commonly form the nucleus of clay iron-stonenbsp;nodules.

Wood petrified in fluor-spar is very rarely found, but it occurs occasionally in the Rothliegende of the Erzgebirge, and is particularly mentioned by Knop^ and SterzeH. Petrifaction in gypsum is still morenbsp;rare ; the only instance of it which I have been able to find in thenbsp;literature is that of the .stem of a Conifer, which G�ppert � obtained fromnbsp;the gypsum-quarries of Katscher in Silesia, and has described under thenbsp;name of Pinites gypsaceus. It is moreover doubtful whether the specimen is truly petrified, since it shows a brownish colour in places and isnbsp;extremely rich in bituminous substances. Calcium triphosphate is alsonbsp;known as a petrifying agent; roundish lumps of this material containingnbsp;well-preserved and determinable woods are found, according to Vater^, innbsp;abundance in beds of phosphorite in Brunswick. Portions of the wood ofnbsp;Calamites preserved in this phosphate, according to Stur�, are found also in

e uppermost beds of the Coal-measures. Grand� Eury ^ reports the presence � ��ilar fossils in the �couche des Rochettes� and the �couche des Littes.�

Barytes, pyrites, red and brown iron-ore, argentiferous copper-glance, ^nd argillaceous earth are also said by various authors to be petrifyingnbsp;agents . How far the remains of plants preserved in these insoluble compounds can really be regarded as true petrifactions must be considered in a

Lastly, amber must be mentioned as an organic medium of petrifaction so far as it incloses small pieces of coniferous wood perfectly resinisednbsp;^iid Sunk in the amber, but with their substance still preserved, as we learnnbsp;Lorn Berendt and G�ppert�. Other organic inclosures in amber show anbsp;different behaviour.

While then true petrifactions are known by the fact that every part of ^heir substance is permeated by the petrifying material, incrusted remainsnbsp;on the contrary merely surrounded by the incrusting mass and inclosednbsp;R; their substance is not otherwise affected, and may in process of timenbsp;changed into coal, or, if the inclosing mass is of a porous nature, maynbsp;Entirely decay and disappear. This has happened, for example, to all thenbsp;wiany insects and flowers which have been inclosed in amber. Thesenbsp;According to Conwentz^ are represented by cavities, in which slight tracesnbsp;pf coal only are found. All the sculpturings on the outer surface of thenbsp;'^closed object are of course preserved on the wall of the cavity; an impression of the object is taken, whatever may become of its substance, andnbsp;^his impression appears on the opposite faces of the cavity when it is brokennbsp;Across. When the upper and under sides of the object differ in character,nbsp;IS the case with bifacial leaves, these differences appear on the two facesnbsp;socn as any coal that may be present is removed. The finer the grainnbsp;the inclosing mass, the more beautiful will be the impression, most beau-^iful in soft clays and argillaceous schists, much less good in sandstones;nbsp;yet serviceable impressions are sometimes found in tolerably coarse-grainednbsp;Conglomerates.

In many cases the remains which were to be inclosed had Interior ^''^ities of their own, as is commonly the case with stalks, fruits, and seeds.

nese cavities became also filled with the enveloping material, and a cast ^ns produced, the surface of which shows the sculpturing on the outernbsp;ounding surface of the original cavity. The space between the cast andnbsp;o mould is usually filled with coal; it may be hollow through previousnbsp;ecay of the part of the plant, but this must be regarded as a rare con-ion in the preservation of the remains. On every heap of debris fromnbsp;�n Coal-measures are found the casts of Calamites in abundance, in many

cases still covered with their rind of coal, where this has not remained attached to the mould. Of this kind are the so-called Artisiae, casts of thenbsp;pith-tube of stems of Cordaitae. They may be squeezed quite flat, or theynbsp;may still show their natural rotundity. As a rule the cast is of the samenbsp;substance as the enveloping mass; in some instances the two may be ofnbsp;a different nature. This may be the case if the part of the plant wasnbsp;incrusted at the moment when there was a change of sediment, and thennbsp;the envelope will always belong to the older, the cast to the newer layernbsp;of material.

In the casts hitherto spoken of the surface must necessarily show entirely different sculpturings from those of the mould ; the reflection ofnbsp;the latter must be found on the surface of the layer of coal which separatesnbsp;the two, and there it may sometimes be observed in a very delicate form.nbsp;Such cases it is true can very rarely be seen in our collections,�thoughnbsp;I have in my pos.session a Sigillaria the surface of which is wonderfullynbsp;preserved in the rind of coal,�first because the coal as a rule falls to piecesnbsp;very quickly when exposed to the air, especially if it contains pyrites, andnbsp;secondly because collectors in their want of understanding often injure theirnbsp;specimens by carefully cleaning them. But, as has been already said, if thenbsp;organic substance of the inclosed plant has entirely decayed and disappeared,nbsp;and the resulting cavity, as sometimes happens, is occupied by the envelopingnbsp;material or by some other substance, the cast thus produced will itselfnbsp;fill the mould and present an exact impression taken in this form of thenbsp;surface-features of the inclosed plant, the same Impression as is shown innbsp;the other case on the outside of the rind of coal. The Pliocene andnbsp;Quaternary tuffs of Meximieux near Lyons and of Cannstadt inclosenbsp;countless holes and cavities, from which the vegetable substance hasnbsp;entirely disappeared ; these are so many moulds, in which we can restorenbsp;it bodily with all its external characters by forcing melted wax with thenbsp;aid of the air-pump into the pieces of tuff, and then dissolving the calciumnbsp;which surrounds them by dilute hydrochloric acid. P'ine specimens of thenbsp;kind are exhibited in the Paris Museum. In the collection also at thenbsp;Sorbonne there is a series of such preparations obtained by Munier Chalmasnbsp;from the lower Eocene tuffs of Sezanne ; the most remarkable of themnbsp;is a flower of Byttneriaceae with all its parts well preserved. We oftennbsp;find the same process carried out in pyrites, only there it is the work ofnbsp;nature herself; another instance is that of the fern-leaves of the Carboniferous beds of the Tareiitaise, which glisten white and conspicuous onnbsp;a dark ground ; in these the substance which has disappeared has beennbsp;replaced by a cast of magnesium silicate which fills the cleft-like cavity.

It is evident therefore that in examining specimens of this kind careful attention must be paid to the relations of form between the cast and thenbsp;mould, and this care will be the more necessary, because circumstances now

to be mentioned may add considerably to the complications. Both mould and cast in the same object, for example in a stem, may turn out^ quitenbsp;differently according to the condition in which it was inclosed in thenbsp;petrifying substance, a fact to which Steinhauerb as far as I know, wasnbsp;the first to call attention. For example, every one is acquainted with thenbsp;ordinary impressions of SigiHaria, such as are common on every heap ofnbsp;refuse from our coal-pits, which answer to the outer surface of the epidermisnbsp;and are characterised by the projecting rib-like orthostichies with the leaf-

Dictyoxylon-structure of the rind as it occurs in some Lepidodendrae and Sigillariae, and in Lyginodendron, of � .A ^fa-nsverse section of the outer rind of Lepidodendron rhodumnense, B. Ren., showing the anastomosing platesnbsp;which bound the meshes filled with parenchyma; the longitudinal section is quite similar, only thenbsp;sgnbsp;nbsp;nbsp;nbsp;elements are seen in elongated form. j�gt;�impression of the inner side of such a Dictyoxylon-rind

from the stem. The ribs are more prominent owing to the disappearance of the parenchyma, and answer to ^^�^ows. The rhombic cushions fill the depressions caused by this disappearance of tissue in the meshes. A afternbsp;��Wault2, ^

Scars marked on them at regular distances. The examination of silicified specimens shows that the parenchyma of the rind of these plants wasnbsp;traversed by a net-work of sclerenchymatous strands forming verticalnbsp;elongated meshes of irregular rhombic form (Fig. i A). Now impressionsnbsp;exactly reflecting this structure are found, though not too frequently, innbsp;'''hich the rhombic areolae appear as similar convex projections of unequalnbsp;elevation (Fig. i B). There are many reasons for believing that in thesenbsp;objects, which look so unlike one another, we have merely the impressionsnbsp;ef stems of Sigillarias stripped of their rind, and with the net-work of

lignified ribs projecting on the surface above the shrunken parenchyma. Williamson * has explained this peculiar state of preservation. As thenbsp;rind of the Sigillarias went by the name of Dictyoxylon, Will., when itsnbsp;connection with the stem was not yet recognised, the word, though nownbsp;superfluous, may still be used to designate this particular form of structure.nbsp;There are many species from the Carboniferous which had these Dicty-oxylon-rinds.

Other plants beside the Sigillariae, the Lepidodendrae for example, occur in the form of impressions which represent the different surfaces of denudation of the stems. In transverse sections through the casts of Stigmariasnbsp;we often observe a narrow circular line of fissure which appears to be fillednbsp;with traces of coal. Longitudinal fracture shows that this line answers tonbsp;the bounding surface of a second exactly cylindrical cast lying within thenbsp;other, and having its surface marked by entirely different and characteristicnbsp;features of its own. There can be no doubt that this inner cast owes its originnbsp;to the circumstance, that on the destruction of the inner tissue previously tonbsp;the filling in with mineral matter a hollow cylinder of tissue answering tonbsp;the inner side of the secondary wood resisted decay longer than the rest,nbsp;so that when it disappeared two hollow cylinders of preserved tissue remainednbsp;lying one inside the other. The inner cast answers to the inner spacenbsp;occupied by the inner tissue, the outer to that occupied by the outer. Thenbsp;dividing layer cannot indeed have been very substantial, for in that case itnbsp;must have appeared in the form of an evident rind of coal.

A quite peculiar and usually rare kind of mould and formation of a cast has recently played an important part in the controversy which has arisennbsp;between Gaston de Saporta^ and Nathorst� respecting the algal nature ofnbsp;certain fossils. In some regularly stratified deposits (Saporta gives as hisnbsp;chief instance the Kimmeridge strata of Cirin with branches of coniferousnbsp;plants) on the under surface of the beds casts are found, which project innbsp;half-relief only, and fill corresponding depressions forming half-moulds innbsp;the bed as it lies. There is no rind of coal; mould and cast show the samenbsp;sculpture negative and positive. There are only two ways of explainingnbsp;such cases as these. They may have arisen from the investment of partsnbsp;of plants which contained little solid material and much water, and whichnbsp;soon collapsed, such as are of frequent occurrence among Algae. The thicknbsp;algal thallus collapsed immediately after investment, the mud which coverednbsp;it being still soft sank with it, and the organic substance was so scanty thatnbsp;it oozed away in the under-layer, or at any rate could not give rise to anynbsp;appreciable quantity of coal. But this mode of explanation does not suitnbsp;branches of Conifers, and in their case we can only imagine, that after beingnbsp;deposited in the mud they were then removed from their beds by subse-

quent denudation of the covering mass, and that these beds served later on as moulds for succeeding deposits, exactly as in the case of the tracks ofnbsp;crabs described by Nathorst. A similar explanation may be given of thenbsp;leaves of Nymphaeaceae from Tertiary formations adduced by Saporta^ innbsp;his elaborate account of this � fossilisation en demi-reliefin the case of thenbsp;fragments of the rhizomes of the same plants shreds of the epidermis may havenbsp;heen set free by the rotting of the plant, and been floated into the placenbsp;where the fragment was being preserved. A careful examination of thisnbsp;question will be found also in the introduction to Delgado�s work^.

Coal-seams, or coal-streaks as they are termed when they are only slightly developed, are a very special kind of incrustation. The only difference between them and the impressions of plants hitherto described is, thatnbsp;*n their case not single fragments but huge deposits of vegetable remainsnbsp;incrusted together with conversion of their substance into coal, and arenbsp;enclosed in a mass of material which hardens into stone. The oppositenbsp;laces in the impression are in this case the roof and floor of the seam, andnbsp;parts of plants which happened to lie on the surface of the seam, and whichnbsp;*^annot now be distinguished in the coal itself, are not unfrequently shown innbsp;Well-preserved moulds in the bounding surface, especially in the roof. Manynbsp;instances of the kind are adduced by G�ppert�, who found in the roof ofnbsp;noal-seams in Upper Silesia impressions of one side of large tree-stems whichnbsp;nould sometimes be traced for a length of several metres.

It is in a very small portion only of the coal-seams that their origin from fragments of higher plants can be readily seen at the first glance. This isnbsp;naost frequently the case in the brown coals of the more recent formations;nbsp;It occurs much more rarely in the coals of the mesozoic and palaeozoic ages.nbsp;An excellent example is afforded by the coal-beds of Central Russia,nbsp;learn from GopperUi that at Malowka in the Government of Tula,nbsp;besides more compact kinds of coal there is one which consists entirely ofnbsp;flakes, like sheets of paper, loosely united together and pierced with littlenbsp;boles, and that closer examination shows that these flakes are shreds ofnbsp;Ibe cuticle of Lepidodendreae (Lepidodendron tenerrimum, Eichw., Bothro-flondron punctatum. Grand� Eury). They are so slightly coherent thatnbsp;Ibey Can be blown apart by the wind. Nevertheless these coals belong tonbsp;Ibe oldest formation, which generally contains beds of the most compactnbsp;^oal; for geologists, though they differ in opinion on particular points,nbsp;^�ree in placing them on the horizon of the Carboniferous limestone.

The older coals, the pit-coals, are usually compact, more or less phistose and tolerably homogeneous, dull or bright, and of a black colour.

as was done by the earlier writers. It was by different ways that men at length arrived at the conviction that they are all of organic origin, and thatnbsp;they consist of fragments of plants in a greatly altered condition, placed innbsp;layers one above another, and firmly caked together with the help of a finenbsp;silt or detritus.

One way was the examination of thin sections of coal under the microscope�a method first adopted by Witham ^ in 1833, and recently employed by Reinsch and by Fischer and Riist We are still looking for thenbsp;results of similar investigations commenced by Williamson some time ago.nbsp;In this way we have learnt that anthracite in the mass is almost absolutelynbsp;homogeneous and non-transparent. A few evident traces of the tissue ofnbsp;the higher plants were detected in anthracites, together with a great numbernbsp;of small spaces or areas occupied by a transparent orange-yellow or garnet-red substance, which might certainly be compared to cells filled withnbsp;secretion, though very dissimilar in shape. The substance of these areasnbsp;is said by Fischer and R�st to consist of resin or some hydrocarbon ; it burnsnbsp;readily, and is partially soluble in carbon bisulphide or in ether, the dissolved portion crystallising in needles on evaporation of the solvents. Thesenbsp;areas are much more abundant in cannel coal than in anthracite. Bogheadnbsp;coal from Scotland appeared to be almost entirely composed of them.nbsp;Large quantities of hydrocarbon may be obtained according to Muck^ fromnbsp;coals of this description by treating them with ether, and the solutionnbsp;is beautifully fluorescent. Reinsch, who also observed these brown-colourednbsp;areas, saw in them the remains of organised structure ; he recognised in thenbsp;mass of coal, that is, in the small partial layers of the seam, stromata withnbsp;cavities interspersed, and considers them to be the product of membranelessnbsp;protoplasm-masses springing from lower organisms. In pre.sence of thenbsp;botanical investigations which we shall have to notice, we need not gonbsp;further into these fancies, which must not be taken seriously.

The probability of our getting sight of organic fragments to any considerable extent on the surface of a section of coal was never verynbsp;great. It is not surprising therefore that greater success was attainednbsp;from the first by simply breaking up the coal into very small splinters,nbsp;and endeavouring to make these transparent by means of petroleum.nbsp;Link � especially, and G�ppert also, pursued this method, and the latternbsp;demonstrated the presence of the skeletons of single cells and fragments ofnbsp;vessels in coal-ashes.

But by far the most important method of investigation was that tried by Schmid and Schleiden'^, who endeavoured to reduce the compactnessnbsp;of the coal by maceration. Their imperfect mode of treatment with

gt; Witham (1). nbsp;nbsp;nbsp;Reinsch (1).nbsp;nbsp;nbsp;nbsp;� Fischer (1) (Fischer und Riist). * Muck (1), p. 4S.

Link (1). nbsp;nbsp;nbsp;^ G�ppert (2).nbsp;nbsp;nbsp;nbsp;� Schmid und Schleiden (1).

sodium carbonate was not without success; but F. Schulze ^ obtained much naore important results by maceration with the fluid which is named afternbsp;him, and by subsequent treatment with ammonia. In this way, especiallynbsp;if the treatment is continued for a long time and the temperature is notnbsp;mised, it is in fact possible to isolate fragments of tissue in large quantitiesnbsp;from most kinds of coal. I have seen single .scalariform tracheides andnbsp;groups of the same, and spores of every kind in excellent preservation innbsp;original preparations by Schulze, and have convinced myself by repeatednbsp;trials of the suitableness of this mode of proceeding. The method has beennbsp;ifuite recently improved by Giimbel who has substituted absolute alcoholnbsp;for ammonia in washing the specimens, since it was found that parts still preserved and showing the form of the remains were dissolved by the ammonia.

The tissue-remains which can be thus isolated in the coal are in the great majority of cases such parts of the plant as have their membranesnbsp;strongly cuticularised, spores for example, and bits of cuticle which shownbsp;f^re gaps for the stomata. These objects are in general well preserved,nbsp;though great caution must be observed in judging of the details of theirnbsp;^orm, because cuticularised membranes from a certain plasticity which theynbsp;Possess are apt to suffer changes of form, which long experience alone cannbsp;triable the observer to recognise as artificial with any degree of certainty,nbsp;ft will be an important work to examine the epidermal structure of the rindnbsp;^f coal in known fossils on a more extended scale with the aid of thenbsp;Methods here described, since comparatively little can be learnt on this pointnbsp;horn thin slices. We owe much the largest part of what has been done innbsp;fhe way of this examination of the epidermis to the labours of Schenk,nbsp;^ho has been careful in all cases to examine the carbonised coating of thenbsp;irnpressions, and has generally obtained connected shreds of cuticle, evennbsp;where the component parts of the rest of the tissue could no longer benbsp;'flstinguished. Fragments of the membrane of highly lignified elements,nbsp;^oalariform tracheides for example, are much less frequently obtained; atnbsp;'�he same time they are always almost entirely unchanged, showing pitsnbsp;^nd bordered pits sharply defined. Their fragile nature, for they split upnbsp;�*^10 diminutive angular pieces, explains perhaps the rarity of their occur-�quot;^nce. Spiral tracheides and sclerenchyma-cells out of shape are observednbsp;here and there, while ordinary parenchyma is scarcely ever seen. Muchnbsp;Useful information on these points is to be found in Reinsch�s� work, onlynbsp;'''e must disregard his interpretations.

We may now proceed to consider how far the results obtained by wgt;any observers from the examination of the coal-seams themselves gonbsp;to prove that compact coal is composed of the fragments of plants. Thesenbsp;�quot;esults are to be seen collected together in G�ppert�s^ larger treatise, where

� F. Schulze (1). nbsp;nbsp;nbsp;a Giimbel (-2'.nbsp;nbsp;nbsp;nbsp;Reinseh (1).nbsp;nbsp;nbsp;nbsp;� Goppert (14).

there is also an account of his own protracted researches, especially in the coal-districts of Silesia. First of all coal-seams are found which may benbsp;directly shown to be composed of the stems of Sigillaria and Lepidoden-dron, for impressions of these plants may be seen in abundance on thenbsp;bounding surfaces of every layer. Such seams are found in England, butnbsp;according to Lindley and Hutton ^ they do not seem to have been oftennbsp;observed there; in Upper Silesia they are quite common. Two instancesnbsp;may be given from the many cited by Goppert. He found thick seams in thenbsp;southern district of Gleiwitz or Nicolai which show this character completely.nbsp;These Sigillaria-coals are obtained especially from the Friedrich pit nearnbsp;Zawada. Goppert gives a figure of a piece of coal from the neighbouringnbsp;Leopold pit which shows numerous impressions of this plant lying acrossnbsp;one another in two distinct layers. At Heinrichsfreude near Lendzin thenbsp;coal consists almost entirely of Stigmarias, and these together with thenbsp;many small stems of Araucarites which are said to occur close by themnbsp;would be well worth renewed investigation. At Zawada, moreover, betweennbsp;the Sigillaria-seams were observed smaller layers consisting exclusively ofnbsp;leaves, which Goppert says are the leaves of Sigillaria. At Dombrowanbsp;and Myslowitz flattened stems of coniferous structure were found plentifullynbsp;in the seams, and similar stems at Radnitz in Bohemia. Impressions ofnbsp;ferns also are sometimes though rarely found ; I have seen them myselfnbsp;from the coal (Plattelkohle^) of Niirschau in Bohemia. A further series ofnbsp;examples is supplied by Grand� Eury^ from the coal-mines of Centralnbsp;France. In Avaize the coal consists of Psaroniae, Calamites and Fern-leaves, in other places almost entirely of leaves of Cordaites. The coalnbsp;of the Wealden formation of Duingen in Hanover contains frequent intermediate layers formed entirely of needles of Conifers (Abietites Linkiinbsp;of authors), which may be isolated.

An important part of Goppert�s treatise is devoted to proving that the differences, which we find at the present day in pit-coal, may often benbsp;traced back to the original composition of the substances obtained from thenbsp;remains of different plants and converted into coal. Lindley and Huttonnbsp;had already given utterance to the same idea. Goppert derives his proofsnbsp;from the present condition of the coal itself. Far from consisting of purenbsp;carbon, it is possible that it contains no carbon at all in the free state (seenbsp;Muck �), but only a mixture of hydrocarbons of varying composition andnbsp;compounds of a variety of substances rich in carbon. The chemical constitution determines the practical distinction into caking coal, fritting coal,

Mr. F. \V. Rudler, of the Museum of Practical Geology, sends the following explanation of this word:�� Plattelkohle�also Blattelkohle and Brettelkohle�a bituminous schist in Bohemia,nbsp;like Boghead mineral or like Cannel, and used with ordinary coal in gas-making.�]

^ Grand� Eury (2\ p. 146, nbsp;nbsp;nbsp;^ Lindley and Hutton (1).nbsp;nbsp;nbsp;nbsp;^ Muck (1)*

non-caking coal, and anthracite; the differences are made apparent by the application of heat, when caking coal swells up considerably and liquefies andnbsp;forms coke, but the other kinds do not. The amount of carbon containednbsp;in them increases constantly from caking coal to anthracite, while thatnbsp;of the volatile hydrocarbons diminishes in the same direction, and thisnbsp;change is generally coincident with decrease in the number of the transparent yellow or red areas mentioned above. Coals may also be dividednbsp;according to their external character, colour, texture,�a mode of divisionnbsp;which shows no relation to the one previously mentioned,�and in this waynbsp;We distinguish brown coal or lignite, anthracite, cannel coal and fibrousnbsp;coal (the fusain of the French, fossil wood-coal of older authors).

Ordinary observation teaches us that external conditions have had a great deal to do with causing these differences in the constitution of thenbsp;'different kinds of coal. Every one knows how rapidly coal taken from thenbsp;�^ine changes in the air, how it falls to pieces even when it contains littlenbsp;or no iron pyrites, and thus loses some of its value as fuel. Analogous processes have gone on in the course of time in the seams themselves beforenbsp;removal from the mine. Thus Goppert^ cites many cases in which seamsnbsp;of caking coal in the neighbourhood of that which is being removed changenbsp;gradually into fritting coal and non-caking coal; he states that the two latternbsp;^inds almost everywhere take the place of caking coal at points where greatnbsp;faults traverse the seam and displacements have occurred. Moreover, thenbsp;coal of seams of the most different character becomes anthracitic by contactnbsp;^ith intrusive porphyry, and this is often accompanied with the appearancenbsp;�f Columnar structure. Seams of caking coal also ai'e locally converted intonbsp;coke by similar intrusions ; the eruptive rock may even occasionally changenbsp;fhe coal into graphite. Delesse^ mentions a case of this kind described bynbsp;Bou� from New Cumnock in Scotland, in which the direct passage of coalnbsp;*nto anthracite and graphite may be observed. A similar case occursnbsp;According to Rink in Greenland, where coal is changed into coke, intonbsp;anthracite with a semi-metallic lustre, and even into graphite Hence itnbsp;'quot;^ould appear that caking coal, fritting coal, non-caking coal, anthracite, andnbsp;graphite are successive stages of development, through which any givennbsp;coal-seam may pass. If this is so, there is ground for surmising that somenbsp;layers of graphite, at least of the old formations, are the final condition ofnbsp;^ process of development, which our seams of coal may also in certainnbsp;circumstances eventually reach.

If the seams exposed to these external influences throughout their entire mass in essentially like manner always contained coals of thoroughlynbsp;similar character, we might in that case ascribe the differences which distinguish them from one another exclusively to the different effects of these

influences. This is, however, almost never the case. It commonly happens that layers of very different character alternate in the seams, and as theynbsp;are suitable for different economic purposes, they are kept separate when thenbsp;coal is removed from the mine. The single layer too is seldom of the samenbsp;composition throughout, but is very frequently made up of thin altei'natingnbsp;secondary layers,�of dull, for example, and of highly lustrous coal. Further,nbsp;in many places, such as Upper Silesia, Zwickau, and St. �tienne, fibrousnbsp;coal is found in irregular nests, masses and strips breaking through andnbsp;traversing the other kind of coal, so that the whole assumes a highlynbsp;complicated structure, which varies from case to case and has been takennbsp;into consideration in naming the different coals. Thus anthracite, which isnbsp;traversed by an unusual number of layers and strands of fibrous coal, isnbsp;termed sooty coaP, and as in such cases the parts of the seam which are ofnbsp;like character were exposed to the like external influences, the difference innbsp;detail must depend, as G�ppert concludes, on the originally dissimilarnbsp;character of the material employed in the formation of the coal. This dissimilarity we may ascribe with G�ppert to the association of differentnbsp;species of plants in varying proportions, or with Grand� Eury^ to thenbsp;bringing together of parts of plants, in which specific difference hadnbsp;less effect than the varying degree of decay and maceration in each case.

To increase the probability of all these conclusions, G�ppert� also set himself to test them by the method of experiment. Similar attempts hadnbsp;been already made by Wiegmann, and after him by PetzholdF*. Unfortunately they were none of them thoroughly and logically carried out.nbsp;G�ppert experimented with portions of plants in closed vessels with waternbsp;at a temperature of 60-80� R., and for a period extending over severalnbsp;years, and he states that his material formed at length a brown coal-likenbsp;mass. Lustre and black colour were only obtained by addition of a smallnbsp;quantity of sulphate of iron. Coarse cloth which covered the cylinder in anbsp;cloth-manufactory, after being many years in use, was found to be convertednbsp;into black coal with conchoidal fracture. Unfortunately none of thesenbsp;substances was examined chemically; we do not know therefore how far itnbsp;could be compared with true pit-coal.

From all that has been ascertained through the efforts of different observers, there can be no longer any doubt that layers of coal have beennbsp;formed of fragments of plants and of vegetable detritus under water; andnbsp;therefore we have long seen the necessity of studying analogous processesnbsp;going on before our eyes at the present time under similar conditions,nbsp;namely those which i-esult in the formation of peat and brown coal.

held up by impermeable strata and remaining on the surface fj.nbsp;nbsp;nbsp;nbsp;time, thus protects the parts of plants which find their way into it

g;e takes place with formation of hydrocarbons and acids rich in carbon t us-acids). By this means the vegetable mass, which to some extentnbsp;s up into diminutive fragments, becomes converted in comparativelynbsp;' periods of time into a tolerably homogeneous brown to brownishnbsp;pulpy substance, the constituent elements of which can no longer benbsp;perceived without minute examination. Two kinds of peat essentiallynbsp;eient from one another may be distinguished according to the mode ofnbsp;ation, and especially also according to the plants which suppliednbsp;the material!.

There is, first, the peat of meadow peat-mosses and lake-marshes (low-quot;u or lake-turbary), such as so often occupy the bottoms of valleys and other depressions in the north of Germany, or are found everywhere accom-P^uying the course of streams and covering a greater or less extent of ground.

^'^^h peat-beds are in their first stage generally lakes bordered by marshy �!ound, but the remains of vegetation gradually push forward from the edgenbsp;^ the lake and ultimately form an unstable covering over the whole surfacenbsp;^ the water, and continually sinking to the bottom there collect and fill upnbsp;. � l^ke, which thus passes into its second stage. The plants which form thenbsp;fluking mass of peat are mainly Cyperaceae, with some grasses and othernbsp;^ngiospermous growths and a few mosses. The mosses are not Sphagnanbsp;us Hypneae, Aulacomnion, Meesia, Philonotis, and similar forms.nbsp;_ c matter which covers the bottom of the lake is a brown detrital massnbsp;^!!lt;ed with many membranous shreds of roots, leaves and leaf-sheaths.

peat-mosses of this kind, if the depth is not too great, Phragmites '^ulgaris plays an important part. With them may be classed the swampsnbsp;P the coasts of North Germany, which through sinking of the land or thenbsp;!'!gt;ption of the sea are now below the sea-level, and are overlaid by sandnbsp;beds of clay. Here the decay of the component substances is lessnbsp;Puifect; the leaves and stalks of reeds may be quite plainly distinguishednbsp;^ the exfoliating peat. These products are much less valuable than thenbsp;bOod rich peat formed in meadow peat-mosses and deep lake-marshes.

We have, secondly, the peat of peat-bogs (mountain turbary), which is Proper rather to mountain districts, but may develope in favourable circumstances Upon the basis supplied by former peat-mosses. In northern countries,nbsp;especially in the neighbourhood of both poles, peat-bogs are common atnbsp;levels; in the lowlands of Germany they occur chiefly on the expansesnbsp;�hnbsp;nbsp;nbsp;nbsp;ground which separate the river-valleys from one another. Of all

examined by Grisebach^, and those of the table-land of Upper Bavaria by Sendtner^. Peat-bogs are formed only where Sphagna find facilities fornbsp;their free development, where, as the first condition, they have water atnbsp;command which was either free from lime from the first, or at any ratenbsp;which no longer contains lime in solution. It is true that according tonbsp;Grisebach, with whom most modern writers agree on this point, the Sphagnanbsp;by themselves produce only a very poor peat, which is known as moss-peat,nbsp;a loosely felted brown mass which never becomes true brown heavy peat.nbsp;But by their vegetation they enable other plants, the Ericas especially, tonbsp;thrive on the surface of the bog, and the remains of these plants give rise tonbsp;a true peat of a similar character to that of the peat from the lake-marshes.nbsp;A peat-bog of this kind always begins with a colony of Sphagna, whichnbsp;growing upwards in compact masses die down below and thus raise thenbsp;surface, while they hold the water like a sponge. When the .surface of thenbsp;bog has thus become convex, it begins to dry up and is covered with plantsnbsp;which grow in clumps�Erica, Betula nana, Scirpus caespitosus, and others.nbsp;The remains of these plants falling to the ground are enveloped by thenbsp;Sphagna, and are thus withdrawn from the influence of the air. In thisnbsp;way an upper heavier layer of peculiar character is gradually formed, thenbsp;weight of which depresses the general mass of the bog, and more favourablenbsp;conditions of growth and a more copious supply of water are naturallynbsp;secured for the Sphagna. By the continuance of this process the moss-peatnbsp;is compressed, and sinks deeper and deeper in the bog beneath the weightnbsp;of the overlying and constantly growing mass. Grisebach found in thenbsp;bogs of Ems a thin layer of compressed moss-peat, the original Sphagnum-bed, forming the base of the black peat. The deepest layers of these peatbogs are often found to contain large tree-stems only slightly maceratednbsp;and altered, and erect stumps of trees. In this case the peat-bog wasnbsp;developed in a wet and wooded spot, and gradually destroyed the treesnbsp;and closed over their prostrate stems. We may observe this process goingnbsp;on at the present day in our own mountain districts, in the Harz and innbsp;Th�ringen; forestry in these highlands is everywhere at strife with thenbsp;peat-bogs, which left to themselves are always growing, and by the advancenbsp;of their margins eat their way into the adjoining forests and make irregularnbsp;gaps in them. To put a stop to this process the administration is chieflynbsp;and constantly engaged in draining and planting the ground, though treesnbsp;do not thrive at such an elevation and in such a soil, and they can never benbsp;expected to repay their cost.

Lignite or brown coal, of a brown, brownish black, rarely black colour, and always streaked with brown, much richer in hydrogen and oxygen than

often inclosing pieces of wood in good preservation, is widely ^^used through the strata of the Tertiary and Quaternary formations.

sre is no doubt that it has usually proceeded from substances of the same character as our modern peats. All intermediate states are foundnbsp;Ween true lignite and normal marsh peat or lake peat with pieces ofnbsp;Wood and stems of trees occasionally imbedded in them. The connectionnbsp;established especially by the slate-coal, as it is termed, of the Quaternarynbsp;^rniations of Utznach and Diirnten in the north of Switzerland, and innbsp;Pper Bavaria. Proof of this is supplied at great length by Heer^ andnbsp;nibel^. Lignite occurs in many cases, as is well known, in rottennbsp;crumbling masses, which must be pressed in moulds before they can benbsp;Used; in other cases it contains less water and has a slaty cleavage, butnbsp;�ldl tolerably homogeneous. The formation of all the above coals findsnbsp;Unmediate parallel in that of the peat of our lake-marshes. But this isnbsp;^ot the case with the lignite from other formations, which is composed fornbsp;c most part, sometimes almost exclusively, of accumulations of well-Preserved stems of trees capable of being split like firewood, and occasionallynbsp;^llernates with layers consisting entirely of leaves. These deposits werenbsp;^^ubtless formed in a different manner, but in their case also we havenbsp;. ^coughly suitable objects of comparison from our own times. We maynbsp;�quot;fin first the colossal masses of tree-stems which are carried down by thenbsp;�ieat American rivers, the Mississippi, for example, and the Mackenzie, andnbsp;posited in lagoons in the lower part of their course, and in the stagnantnbsp;^^ters of their deltas. Entire layers of such stems are actually found innbsp;0 delta of the Mississippi buried deep in sand and mud, which thoughnbsp;onging to the most recent alluvial strata have already assumed thenbsp;racter of a true brown coal�. That this alteration of recent wood setsnbsp;^ory quickly may be gathered from various observations. For instance,nbsp;Some wrought timbers, buried in the � Old Man � of the Rammelsberg, innbsp;mine of St. Joachim near Zellerfeld, and in that of Dorothea nearnbsp;^usthal, were disinterred according to Hirschwald ^ and Hausmann� onenbsp;thnbsp;nbsp;nbsp;nbsp;hundred and fifty years perhaps after they were put up in

mines, and were found to be in a soft and moist condition, but when dry y proved to have been converted into a lignite of a black colour andnbsp;i^ous conchoidal fracture. Goppert had before observed timbers in thenbsp;-mines of Charlottenbrunn, which after being kept in them for a longnbsp;th' ^ converted into lignite. Unger � has described a piece of wood ofnbsp;IS kind from the iron-mines of Turrach in Styria, which had suffered anbsp;alteration, as was shown by analysis. But the most striking proofnbsp;1 e shortness of the time required has been supplied by Mietzsch'^. He

found in the coal-mine at Planitz near Zwickau, in a working which had been opened six years before but had meanwhile fallen in, a piece of woodnbsp;several decimetres long which was entirely changed into a dark brownnbsp;coal. All these alterations Hausmann refers directly to the effect of the sulphuric acid arising from the pyrites. Even the coals of the Coal-measuresnbsp;may have I'eached their ultimate condition in a comparatively short time.nbsp;This is suggested by the remarkable rolled fragments of coal of Commentrynbsp;and Champagnac les Mines, which have their edges sometimes still sharp.nbsp;These fragments, the description and bibliography of which will be foundnbsp;in de Lapparent are a component part of the Carboniferous conglomeratenbsp;which lies above and below the coal-seams; seams of coal must thereforenbsp;have been in existence at the time when the conglomerates were formednbsp;from their erosion and destruction.

Again, we may compare the lignite-formations in question with the extensive woody swamps along the east coast of N. America from Virginianbsp;to Florida. We are indebted to Lyell^ for a description of one of thenbsp;largest of these, which lies not far from the sea in the neighbourhood ofnbsp;Cape Hatteras and is known by the name of the Great Dismal Swamp.nbsp;It is composed of a black pulpy ooze overrun and concealed by a densenbsp;tangled covering of low shrubs, in which large trees, chiefly Taxodiumnbsp;distichum and Chamaecyparis sphaeroidea, have taken root. These treesnbsp;sometimes sink of themselves in an upright position in the ooze, or they arenbsp;blown dowm by the wind and fall into it, in which case their woodynbsp;substance remains in a state of perfect preservation. Great quantities ofnbsp;valuable wood are thus fished out of the swamp. It is a remarkable factnbsp;that in consequence of the covering of vegetation which prevents the dispersion of the waters the middle of the swamp is occupied by a large lakenbsp;some twelve feet higher than the surrounding land.

Fi'om all the evidence which has been collected up to the present time we may without hesitation refer the formation of the coals of every periodnbsp;in the earth�s history, from peat backwards to graphite, not indeed tonbsp;identical but to analogous processes. It would be going too far to connectnbsp;them all together in one series of developments and to assume that pit-coal had at first the character of lignite, and that our deposits of lignitenbsp;would in course of time become coal; on the contrary, this mode of formation was affected in each particular case by external influences whichnbsp;were different at different times, as is clearly shown by the rolled coal-fragments mentioned above, and by the coals from the lower beds of thenbsp;Coal-measures of Central Russia which occur in conjunction with true coalnbsp;and also with deposits resembling lignite. So far we may consider thatnbsp;there is at present a general consensus of opinion.

ut with this general idea of the process in question we are still far rom having a thorough understanding of it. On the contrary we are con-With a succession of new doubts. There is the question often raised bynbsp;u earlier authors, where the plants grew whose remains we now see gatherednbsp;s tier into coal-seams. The question has been answered in more than onenbsp;Some have thought that coal was formed in the sea by the accumu-ton of sea-weeds, but this view was soon set aside by further investigation.nbsp;^ 6rSj as Count Sternberg and Bou�, appealed to the trunks of trees in thenbsp;ssissippi^ and conceived of masses of drift-wood accumulated by mightynbsp;^^ers. G�mbeP named this view the theory of allochthonous origin.

ers again have sought a probable explanation of the matter by a comparison with our present peat-bogs and made the entire material of the Coal-seams grow m loco, adopting therefore the theory of autochthonousnbsp;This view was defended in the eighteenth century by Bereidingennbsp;de Luc, and it was accepted with gradually increasing decision by mostnbsp;� the eminent geologists and palaeontologists, especially by A. Brongniartnbsp;Liig (jg Beaumont ^; it was completed and put into consistent shape bynbsp;. PPert�, and Unger ^ accepted his ideas with some reservations. Thenbsp;y�cw intermediate between these two, that the mode of formation varied asnbsp;^ the case of the lignites and was sometimes allochthonous, sometimesnbsp;^'^tochthonous, also makes its appearance with more or less distinctness,nbsp;^specially among the older autochthonists. G�ppert opposed this theorynbsp;^ _ the most decided manner, repeatedly pointing to the extraordinarynbsp;Uniformity in the layers of coal in all parts of the world. We shall seenbsp;P'^csently that it has recently reappeared with certain reasonable limitationsnbsp;nnder the auspices of Grand� Eury�.

G�ppert'¹ and Unger'', and before them Lindley and Hutton�, adduce ^nny weighty arguments to show that the assemblage of phenomena pre-�^nted by the seams of coal cannot be explained by the assumption of annbsp;thnbsp;nbsp;nbsp;nbsp;origin. On this assumption, says G�ppert, it is inconceivable

^ the coal-seams should cover such enormous spaces in beds that are ^ ywhere alike and are of equal size, and again that coal should be sonbsp;ouiogeneous and so pure in quality that it is rare to find fragments ofnbsp;e inclosed in it. For every stream that was to carry along with it sonbsp;vegetable matter must have been strong and rapid, and would havenbsp;down at the same time mud, sand, and gravel. We should thereforenbsp;0 to find in the seams a regular alternation of coal and inorganicnbsp;�ut this has not been observed anywhere; a comparison withnbsp;thenbsp;nbsp;nbsp;nbsp;living plants shows at most a considerable increase in

Grand� Eury (2). nbsp;nbsp;nbsp;� G�ppert (14).nbsp;nbsp;nbsp;nbsp;¹ Unger (6).

G�ppert (14). nbsp;nbsp;nbsp;� Unger (6).nbsp;nbsp;nbsp;nbsp;� Lindley and Hutton (1);

tion the loss of organic compounds necessarily connected with the process of carbonisation. Again, such powerful streams, as would be required tonbsp;transport the whole of the materials which formed our seams of coal, mustnbsp;have been too turbulent to have been favourable to the preservation ofnbsp;vegetable remains. But we find all the impressions of the plants regularlynbsp;spread out on the planes of stratification in the thin slates of the clay-beds,nbsp;which so often occur in the roof of the seams. The most delicate fern-leaves are beautifully preserved, showing their pinnae in the normal positionnbsp;and never twisted about by the eddies of a stream. All these circumstancesnbsp;are in favour of the view, that the slaty beds also which form the roof of thenbsp;coal-seams were deposited with a quietness which excludes the action of anbsp;strong current.

Unger ^ also is a decided supporter of the autochthony of the beds of coal, but he is at the same time convinced that the bogs of the period ofnbsp;the Coal-measures could not have answered properly to our recent peatbogs, and has distinctly expressed this opinion. He shows quite convincingly ^ that we must on no account imagine that they resembled thenbsp;peat-bogs of our mountain districts, for a uniform tropical temperaturenbsp;prevailed over the whole surface of the earth during the formation of thenbsp;coal-seams, and such a temperature would appear to be incompatible withnbsp;the existence of upland peat-bogs. This is doubtless true ; there are nonbsp;beds of Sphagnum in the tropics, or they form only here and there on thenbsp;highest mountains; and that a uniform temperature prevailed over thenbsp;whole earth in the time of the Coal-measures is certain from the fact, thatnbsp;in deposits of that era from north polar regions to Australia assemblagesnbsp;of plants essentially similar if not identical are found everywhere asnbsp;constituents of the coal. On this point the reader may consult Carru-thers^ for Brasil and also for Queensland^, O. Feistmantel� and Mac Coy�nbsp;for Australia, Dawson^ for Canada and New Brunswick, Heer� for Polarnbsp;lands, Schenk � for China, Zeiller for the Zambesi country. Grey fornbsp;Cape-colony. Unger evidently knew of but one analogous case to whichnbsp;he could appeal in the tropical zone, namely that of the floating islands innbsp;the lake of Tagua in Bengal which are covered with trees and shrubs. Hadnbsp;he been better acquainted with the Great Dismal Swamp, he wouldnbsp;certainly have noticed it, for it would have answered in all essential pointsnbsp;to his idea of the swamps of the Coal-measures. G�ppert^^ had meanwhilenbsp;become acquainted with Lyell�s communications on the subject, and hasnbsp;quoted them in the preface to his work as an adequate representation of hisnbsp;idea of the bogs of the Carboniferous period.

' Unger (6). nbsp;nbsp;nbsp;� Unger (6), p. 135.nbsp;nbsp;nbsp;nbsp;^ Carruthers (7).nbsp;nbsp;nbsp;nbsp;� Carruthers (10).

' O. Feistmantel (1), iii. � Mac Coy (1). nbsp;nbsp;nbsp;� Dawson (8).nbsp;nbsp;nbsp;nbsp;� Heer (5).nbsp;nbsp;nbsp;nbsp;* Schenk (2).

Zeiller (13). nbsp;nbsp;nbsp;� Grey (1).nbsp;nbsp;nbsp;nbsp;** G�ppert (11).

astly, as has been already said, Grand� Eury^ has quite recently opted an intermediate view on the strength both of botanical investi-of loog mining experience. He brings forward a number ofnbsp;doe*nbsp;nbsp;nbsp;nbsp;opposed to G�ppert�s reasons for pure autochthony, and

s not rest his argument solely on the stratified condition of the seams f^�nabeH supposes, for this would not suffice for his purpose.nbsp;0 picture which he draws of the state of the surface of the earth whennbsp;ooal was formed may quite possibly come very near to the reality.

ft is a known fact that fossil remains are usually found in a flat-^ condition; it would appear from many observations of G�ppert, tV^^^nbsp;nbsp;nbsp;nbsp;and others that this is the case also in coal. The cause of

'S phenomenon is usually alleged to be the pressure exerted by the over-I g masses of stone, and this same pressure we have become accustomed ^ regard as the main factor along with the effects of heat and water in thenbsp;^^mation of coal. Grand� Eury shows most convincingly that this actionnbsp;j Pi'essure, if there was any, can have been of only very small importance,nbsp;Ihe famous angular siliceous pebbles discovered by him at Grand� Croixnbsp;'^car St. Etienne, which inclose the petrified material of a layer of coal in thenbsp;of formation, the remains of the plants are for the most part in anbsp;tened form, although they lie loosely on and over one another in thenbsp;pebbles, and there is no trace whatever of any pressure. Both in thesenbsp;pebbles and in normal seam-coal we have the most abundant proof of thenbsp;�'emarkable fact that these flattened stems, roots, and branches consistnbsp;�dy of a tube of rind, from which the inner tissues, and especially thenbsp;^oody axes, have been removed. This is the case not only with thenbsp;^pidodendreae with thick succulent rinds, but also with the Cordaitaenbsp;ich had larger woody bodies and must therefore have been of a muchnbsp;succulent character. It is observed also that if the tubes of rind stillnbsp;^�nbrace their cylinder of wood, the latter is commonly split into irregularnbsp;j. fluents which are often displaced; sometimes single fragments are stillnbsp;�^nd in their place and position while the rest are removed. It is furthernbsp;^^�^arkable that the tubes of rind are very frequently slit up on one side,nbsp;^ then rolled over at one margin of the slit; as a rule also they occurnbsp;y m pieces of moderate length, entire stems being rarely found in thenbsp;^^nis, though, according to G�ppert, these seem not to be so infrequent innbsp;PPer Silesia. Now if coals are of purely autochthonous origin, all thesenbsp;^^stances must appear very strange; on the other hand they are quitenbsp;iigible, if we suppose them to result from the action of a slow stream ofnbsp;r overflowing ground covered with dead and decaying trees and frag-� of plants. We can imagine how in such a case the softened and

Coal-seams in the open air workings of Commentry, the details of which are given by de Lapparent k quite agrees with Grand� Eury�s description of thenbsp;extreme case of allochthony.

Grand� Eury�s conception of the matter is essentially as follows. Coal-seams were formed in broad land-locked lake-basins (lagoons) surrounded y wooded swamps, in which the decaying vegetation softening and rottingnbsp;^ It lay on the ground produced in time a layer of matter of vast thickness.

he water of frequent rain-storms running slowly off in trickling streams gradually carried away with it the softened wood in shreds from inside thenbsp;encasing rind, which was itself ultimately broken up and conveyed withnbsp;ether deposits into the basin. Here the processes which lead to the formation of coal took the place of decay, the mass of the coal being producednbsp;the rind, while the particles of softened wood were converted intonbsp;rous coal. The masses of aquatic and marsh plants, which coverednbsp;^^0 surface and margins of the basins with their luxuriant growth, alsonbsp;supplied their contingent in the form of the parts which died and sank tonbsp;the bottom.

We know that stumps of trees, the remains of former forests, are found 2re and there in coal-deposits, either singly or in groups, and in theirnbsp;natural position. One of the best known cases is that of the fossil Sigillaria-lest discovered by Goldenberg ^ during the construction of a tunnel on thenbsp;Railway from Saarbriicken to Neunkirchen. Grand� Eury gives manynbsp;'Instances from the Coal-measures of Central France, which were brought tonbsp;by the opening of stone-quarries, and in which the chief growths werenbsp;saroniae, Calamodendrae, and Cordaitae ; and though Fayol � is of opinionnbsp;at these plants did not grow where they now stand, but were torn up andnbsp;3ted away and assumed the erect position in the water, it would appearnbsp;^t this may have happened in single cases but can scarcely be true of thenbsp;^hole of the phenomena which have to be considered. England alsonbsp;flushes numerous examples. It is natural to assume from these cases thatnbsp;vras formed in wooded swamps. But Grand� Eury points out that ifnbsp;s Were the case, we should often find such stumps lying across the seams,nbsp;^hh their lower extremity, their roots, immersed in them. The first casenbsp;oes actually occur, but it is so extremely rare that Grand� Eury^ can onlynbsp;off^nbsp;nbsp;nbsp;nbsp;four instances. Elsewhere the stumps are as a rule cut square

ut the bottom of the seam, and they end in the same way where they 2uch decided fissures in the stratification. Moreover they never root in thenbsp;but only in the beds of stone which form the roof of the seam, evennbsp;innbsp;nbsp;nbsp;nbsp;occur close above the seam itself. The coal therefore does not

disintegrated wood might be floated away from the case of rind, which would be quite inconceivable if trees and branches had simply fallen intonbsp;stagnant water. As regards the softening of the wood, we know that this maynbsp;be constantly observed at the present day in wet neglected forests. I havenbsp;myself seen the conditions assumed by Grand� Eury in the case of thenbsp;forests of the Coal-measures very well shown in the B�hmerwald, in thenbsp;primeval forests at Arber and Kubany. We may also compare the description given by Goppert The softening of the wood reduces it to a .shapeless plastic mass, which is easily penetrated in every direction by the rootsnbsp;of other plants (Stigmarias), and settles itself and becomes folded together,nbsp;and thus in many cases so alters the disposition of its elements, that innbsp;wide-celled coniferous woods even the lumina of the individual cells disappear by collapse of the membranes. This is the case with the wood ofnbsp;all kinds in lignite, and constantly strikes the attention of every one whonbsp;examines fossil woods. The timbers from the Dorothea mine near Clausthalnbsp;mentioned above, which were converted into lignite, were moist and of softnbsp;leathery consistence in the place in which they were found, and only becamenbsp;hard after a short exposure to the air. That the woods also from thenbsp;petrified forest of Radowenz were in a perfectly soft state before petrificationnbsp;is concluded by Goppert ^ from the circumstance, that they often show smallnbsp;superficial pits with a bit of flint at the bottom of each pit. These bits ofnbsp;flint must have sunk into the substance while it was still soft.

Amid similar countless fragments of wood which I'otted away on the wet soil of the forest, the flint pebbles of Grand� Croix also occasionallynbsp;contain well-preserved bits of twigs and leaves, and even flowers andnbsp;inflorescences in almost perfect condition. This state of things too wouldnbsp;be very difficult to explain on the theory of a purely autochthonous deposition ; we should rather expect to find all the remains in a nearly similarnbsp;and medium condition. But it would be sure to occur in case of transportnbsp;by running water, which would carry away with it at the same time fragments just fallen from a tree and such as had long lain rotting on the ground.nbsp;Again, without the eddies caused by the confluence of streams we should benbsp;quite unable to account for the frequent enormous accumulations of wood,nbsp;leaves, and seeds in separate heaps. Grand� Eury � gives many examplesnbsp;from St. Etienne of such local accumulations of seeds of Gymnosperms,nbsp;pointing to a succession of deposits in flowing water; a layer of sandstonenbsp;was found in his time in a railway-cutting near Jagersfreude in Saarbriicken,nbsp;which was entirely composed of hard nodules formed of casts of seeds ofnbsp;Gymnosperms and caked together so as to form a conglomerate. Thenbsp;anomalous arrangement also of the beds of conglomerates which overlie the

according to Grand� Eury was produced. The stumps are often hollow, reduced to the rind, and filled with a stony mass in which impressions ofnbsp;parts of other plants are often found. To explain these peculiar conditionsnbsp;Grand� Eury supposes that the temporary raising of the level of the waternbsp;in the basins of accumulation flooded the flat swampy forest-ground far andnbsp;wide, and that the trees were killed by the inundation and became rotten andnbsp;at last fell to pieces, their stumps only remaining erect beneath the water.nbsp;Such behaviour is quite conceivable, if we take into account the smallnbsp;development of wood and the succulent nature of the rind in the trees ofnbsp;the Carboniferous period ; and that something of the kind does take place innbsp;warm climates I was able to satisfy myself in the Botanic Garden at Buitenzorg, where a colossal palm-tree, which had died after developing its terminalnbsp;inflorescence, broke up and fell in pieces before my eyes with a startling crash.nbsp;If the raising of the level of the water was followed by an irruption of thenbsp;adjacent sea into the lagoon,�and this might very well happen when the landnbsp;was so low and flat as in that era,�then the coal-forming basins would benbsp;overlaid by inorganic deposits; and these deposits would envelope the tree-stumps on the margin of the basin and fill the cavity inside them, and bynbsp;local extension of the phenomenon might accumulate large masses of matternbsp;or form thin beds of stone, or bury the whole formation if they were onnbsp;a still more extended scale. If the layers then lost their water, they mightnbsp;harden and pass into the condition of coal. We recall to mind the state ofnbsp;the timbers which in the mine were soft and plastic, but as they dried werenbsp;found to have been converted into coal with a conchoidal fracture.

To the above account of the origin of the incrustations of which coal-seams are an example of the grandest kind, we may here append a brief description of the mode of formation of true petrifactions. These are distinguished from incrustations by being formed only when the object to benbsp;petrified is permeated by dilute solutions of the petrifying substance. Thenbsp;compounds which usually cause petrifaction are apt to produce incrustationnbsp;only when they are in the form of a concentrated solution. On this pointnbsp;we may appeal to the incrusting spring of Carlsbad, to the incrustednbsp;thorns in the drying-houses in our salt-works, and to the siliceous sinter ofnbsp;Iceland and New Zealand. Amber only, which, as has been already said,nbsp;is an agent partly of petrifaction, partly of incrustation, is an exceptionnbsp;in this respect. As resin from Conifers of the Tertiary period it firstnbsp;enveloped any objects which it encountered, and if these were capable ofnbsp;absorbing resin they were gradually and slowly permeated by the enveloping substance, just as microscopic preparations are permeated by canada-balsam. Succulent objects on the contrary were only enveloped by thenbsp;resin, and as the water evaporated it often formed vesicular spaces on andnbsp;around them, which were preserved as the resin hardened into amber. Fornbsp;that amber in spite of the difference in its chemical character is, as is here

assumed, a resin from stems of Conifers which lie buried in layers of lignite thnbsp;nbsp;nbsp;nbsp;beneath the waters of the Baltic, is proved by its occurrence in

e form of tears or as filling fissures in wood of that origin. Fossil resins are obtained from other sources, but the best kinds of the copal and dam-aiar of commerce are dug out of the earth. G�ppert ^ has attempted thenbsp;Artificial production of amber also, and has succeeded in obtaining a substance to some extent resembling amber and almost insoluble in alcoholnbsp;om Venetian turpentine digested for some years at a temperature of 80� R.nbsp;fortunately in this case, as in all similar experiments by G�ppert,nbsp;ohemical analysis was omitted.

^ The insoluble compounds mentioned above, which are said by authors o be agents of petrifaction, cannot of course permeate the substance ofnbsp;f nts. They can at most fill the lumina of the cells, being in this casenbsp;precipitated on the spot from soluble compounds; the membranes are thennbsp;preserved in the form of coal, and may eventually disappear by a slownbsp;process of oxidation. We may look upon this state of preservation asnbsp;intermediate between true petrifaction and incrustation, as an incrustationnbsp;the separate membranes. Few however of the many supposed cases ofnbsp;kind, which Blum ^ especially has collected together in his work, can benbsp;AAid certainly to belong to this category. Among true examples, thosenbsp;�nld first be mentioned in which pyrites is the agent; yet here every casenbsp;rtquires to be carefully examined, because pyrites also occurs not unfre-Buently as a homogeneous mass filling internal cavities, as a simple crystal-cast. In the museum at Jena may be seen fragments of pyritised woodnbsp;preserved in petroleum, which may easily be separated into the threads ofnbsp;eral matter which filled the tracheides, and on these, with the help ofnbsp;� rnicroscope in direct light, we may still see the portions of pyritesnbsp;^hich filled the bordered pits in the form of rows of lenticular prominences.nbsp;Pc substance of the membrane seems quite to have disappeared. Remainsnbsp;A similar character are also mentioned by G�ppert A second and rarenbsp;PASe is that of the remarkable wood of one of the Amygdaleae found notnbsp;infrequently in the tuffs of the Kaiserstuhl in Limburg, which has beennbsp;Preserved by deposition of hydrated clay silicates. Here all the membranesnbsp;c entirely disappeared, and the wood which remains is simply an aggre-SAte of exact casts of cells which may be easily isolated ; the form of thenbsp;A of the medullary rays, of the tracheides, and of the matter filling thenbsp;'vessels is beautifully preserved, and the septa in the vessels are shown by deepnbsp;Annular indentations in the soft substance that filled them. Unfortunatelynbsp;Ac remains of wood can only be preserved by being saturated with gum.nbsp;And even then with difficulty.

of sulphates. Moreover, there can be no doubt that cinnabar, lead-glance, arytes, and sulphur are found merely filling fissures in wood that is in-crusted and turned into coal. Brown ironstone fossils ought as a rule tonbsp;originate in the oxidation of the pyrites, those in red ironstone in thenbsp;ccomposition of the carbonate of iron which was the original petrifyingnbsp;^gent. Lastly, G�ppert � obtained petrifactions in oxide of iron and metallicnbsp;silver by artificial means. These experiments resulted, according to hisnbsp;own account, in the filling of the cells with the precipitates, though imperfectly and with a small amount only of their sub.stance. The skeletonsnbsp;111 silver of parts of plants (Erica mediterranea), which had lain a year innbsp;Concentrated solution of silver, were obtained in their natural form bynbsp;subjecting them to strong heat; gold chloride and platinum chloride arenbsp;�^'d to have given similar results. The less solid skeletons in oxide ofnbsp;iron Were produced in the same way after soaking in sulphate of iron.

Even true petrifaction appears to be often preceded by a complete ^1quot; partial filling of the lumina of the cells. The carbonates of the alkalinenbsp;earths, for example, which, as has been before observed, are the most perfectnbsp;soluble agents of petrifaction, also occur, but more rarely, as substancesnbsp;�^crely filling the cells, and after destruction of the organic matters theynbsp;^0 isolated in the form of spiculae representing the several elements.nbsp;^ have observed this condition in a piece of wood from the Upper Permiannbsp;s of Frankenberg, which contained so much coal that the sectionsnbsp;tii�'^^'^ i^o be entirely opaque; no view of the substance could be obtainednbsp;cellnbsp;nbsp;nbsp;nbsp;beennbsp;nbsp;nbsp;nbsp;removed in the flame of thenbsp;nbsp;nbsp;nbsp;blowpipe, and the

th nbsp;nbsp;nbsp;convertednbsp;nbsp;nbsp;nbsp;into potash had been isolated.nbsp;nbsp;nbsp;nbsp;G�ppert � observed

lo nbsp;nbsp;nbsp;ofnbsp;nbsp;nbsp;nbsp;the process of calcification innbsp;nbsp;nbsp;nbsp;an apparently ana-

�ous manner in recent wood. He obtained some beech-wood from onian conduit at Eilsen in the district of Buckeburg, in the interior ofnbsp;ich Were irregular points of calcification, and these would no doubt havenbsp;'suited if the process had been continued. The same wood has been morenbsp;ob ^ ^ ^^^uiined and figured by Stokes Similar phenomena werenbsp;^ served in the wood of an oak-tree found in a brook at Gera by Herrnbsp;filled*^ � when it was polished, its cells and vessels proved to be entirelynbsp;With carbonate of lime. Another similar case is described bynbsp;��ce , in which groups of points of calcification were found inside thenbsp;u^n piles of a Roman canal at Bourbonne les Bains,nbsp;of T �nbsp;nbsp;nbsp;nbsp;forms of petrifaction may also be distinguished in the case

are * throughout the organic remains, while internal cavities in them ^ory often wholly or partially preserved and form glands lined with

' Solms-Laubach, Graf zu (1), nbsp;nbsp;nbsp;^ G�ppert (1) and (17).nbsp;nbsp;nbsp;nbsp;* Stokes (1),

But there are cases of the kind which we are describing, in which the membranes are preserved and converted into thin black laminae of coal,nbsp;and appear on a transverse section of the clay casts as delicate black linesnbsp;like strokes of a sharp lead pencil. Such cases occur, for example, innbsp;fragments of plants preserved in the Coal-measures of Niedzielisko nearnbsp;Jaworzno in the district of Cracow, for a knowledge of which I am indebtednbsp;to the kindness of their discoverer, F. Romer; his more exact account ofnbsp;them will be found in another place. The specimens collected in the yearnbsp;1865 are irregular obscurely stratified fragments of a very fine clay whichnbsp;may be cut with a knife, of a grayish white colour, but here and therenbsp;rendered quite black by the amount of coal contained in it; each fragmentnbsp;has layers and glands of crystalline pyrites occurring in its substance andnbsp;a rind of impure coal. These fossils come possibly from local lenticularnbsp;deposits of clay in the seams, such as are found, according to Stur^, in allnbsp;the fissures of the coal-seams of Rakonitz in Bohemia, but more exactnbsp;investigation on the spot is no longer possible, as the works have beennbsp;abandoned. They contain seeds of Gymnosperms which are simply in-crusted and have their testa converted into glistening coal, and withnbsp;them numerous objects in the state of preservation of which we arenbsp;speaking. Among these, pending more thorough investigation, may benbsp;mentioned small well-preserved stems of Sphenophyllum, leaf-stalks ofnbsp;Ferns, leaves of Lepidodendron, and a remarkable inflorescence of Cala-maria. The remains showing structure from quarries of the sandstonesnbsp;of the Coal-measures at Chomla near Radnitz, described by Sternberg^nbsp;and Corda �, belong to the fossils which occupy an intermediate positionnbsp;between incrustation and true petrifaction. In specimens of Cycaditesnbsp;involutus, Sternb., which I have had the opportunity of examining, thenbsp;enveloping or petrifying agent is a hard and very fine-grained clay.

Further, Goppert^ found pure copper filling the lumina of single cells and of the large vessels in a piece of recent beech-wood from Mol-dowa in the Banat. The copper appeared everywhere on the transversenbsp;section in the form of scattered roundish glistening points. On the othernbsp;hand it is extremely doubtful whether the branches of Ullmannia innbsp;argentiferous copper-glance from Frankenberg in Flesse is of the class ofnbsp;fossils which we are considering; these fossils, where they are really petrified, are converted into calc-spar; the sulphur seems to have producednbsp;rather incrustation and the filling of fissures; we do indeed here and therenbsp;find casts of cells in this substance, so that a similar process to the fillingnbsp;of the cells with argillaceous earth mentioned above may have taken placenbsp;also here. The pure sulphur may like the pyrites originate in the reduction

Stur (2), p. 647. nbsp;nbsp;nbsp;� Sternberg, Graf von (1).nbsp;nbsp;nbsp;nbsp;� Corda (1).nbsp;nbsp;nbsp;nbsp;* Goppert (17), p. 736.

beautiful quartz-crystals. This is very frequently seen, for example, in the lai'ger seeds of Gymnosperms which are found in the often-mentionednbsp;black pebbles of Grand� Croix.

On the other hand, I have in my possession a piece of wood of a milk-white colour from the Habichtswald near Cassel, and coming probably from the sands of the Drusenthal, which can be broken up into singlenbsp;spiculae answering to the casts of the tracheides, exactly in the mannernbsp;of the silicified and calcified woods mentioned above. The substance ofnbsp;the membranes has entirely disappeared, the spiculae are suspended in thenbsp;interspaces which answer to the walls and are connected together only bynbsp;a fragile froth-like network of very thin lamellae of silica. Schimper ^nbsp;mentions an exactly similar wood, coming indeed from Tasmania, whichnbsp;was given to him by Robert Brown, I have seen another piece of thenbsp;same kind, said to have been brought from Texas, in the botanical department of the British Museum. From these specimens to the silicified woodsnbsp;of Autun, Charles, and other places in the departments of the Sa�ne etnbsp;Loire and Allier mentioned by Renault^ there is obviously but a singlenbsp;step. The latter are certainly solid and coherent, but in the spots whichnbsp;correspond to the membranes they contain a system of very fine pores,nbsp;which readily imbibe drops of water placed upon them. These again arenbsp;merely the small interstices from which the organic substance has disappeared when exposed to the air. Since preparations from these woodsnbsp;in canada-balsam are too transparent, Renault puts them first of all intonbsp;coloured solutions, which remain in these fine pores and show the directionnbsp;of the membranes.

From the accounts which we possess it would appear that the silicifica-tion is accomplished in two ways,�a circumstance which Renault ^ would connect with the difference in the compactness or porousness of the woodnbsp;in different cases. First there is the usual process in petrifactions; afternbsp;the parts of the plants were buried, either the whole of the environmentnbsp;stiffened into a hard encasing mass of silica, or the remains only werenbsp;silicified and thus served as centres of dispersion for the silicic acid, whichnbsp;either entered as free acid in solution, or was extracted from alkaline compounds by the carbonic acid, the humus-acids of the decaying organicnbsp;substance. Proofs of this mode of formation may be obtained fromnbsp;the woods found in the district of Zobten in Silesia and described bynbsp;Conwentz*, which externally have the appearance of lignite, but shownbsp;centres of petrifaction in their interior in the form of hard silicified nuclei.nbsp;Felix � supposes that the wood of the lignite of Gr�bers near Halle underwent the same process; but in it the periphery only is silicified, while thenbsp;central portions can be cut, and burn when lighted.

' Schimper (1), Introd. ^ Renault (2), Introd. � Renault (2). nbsp;nbsp;nbsp;� Conwentz (1).nbsp;nbsp;nbsp;nbsp;� Felix (1)

In the second place, it has long been thought possible, especially by I^�ppert^, that silicification was brought about by the asc�nt of the petrifying substance in the stems, which though dead were still standing erectnbsp;the open air. Such erect petrified stems are mentioned by Hausmann^nbsp;�till rooted in the beds of lignite at the Hirschberg near Gross-Almerode,nbsp;^nd according to Renault � are of not unfrequent occurrence in the depart-naent of the Allier; similar objects were observed by Darwin^ nearnbsp;^spallata on the Andes of South America as snow-white columns risingnbsp;3-bove the ground, but they may, as Darwin supposes, have been laid barenbsp;denudation, and cannot therefore be applied in support of our conjecture. The stumps of trees rooted in the Nubian sandstone of Wadinbsp;Itl Tih near Cairo and mentioned by Newbold and Unger� have nevernbsp;^een seen again, and are doubtful. The possibility of a genetic connectionnbsp;between silicified fossil remains and geyser-springs, which cover everythingnbsp;^ound them with siliceous sinter, I find to have been first suggested bynbsp;Schimper in the Introduction to his �Trait� de Pal�ontologie.�

O. Kuntze �, impressed by the facts which he observed in the geyser district of the National Park Territory in North America and which will benbsp;discussed presently, has since adopted the above idea and combined it withnbsp;^bppert�s view; but he has at the same time extended it in a mannernbsp;'''hich is certainly inadmissible, since he would account for all silicifiednbsp;^ood in this way. He depicts the state of things which he found at thenbsp;oiling Lake geyser in the following words: � I saw the wood in thenbsp;'iiunediate vicinity of the geyser destroyed, and that in a very peculiarnbsp;�banner; where the hot water from the geyser had run among the trees,nbsp;^bey had lost their leaves, rind, and many of their branches, and hadnbsp;^ssumed a white colour, and in some cases their outer substance hadnbsp;ocome soft (see the remarks on this point on p. 21); most of the treesnbsp;^ore still standing, but many had fallen, and of these some were entirelynbsp;dotted inside, whilst others, like those still standing, were in exactly thenbsp;�ame condition as the pieces of wood which had been thrown by visitorsnbsp;^ time to time into the basin of the geyser, that is, they were im-P'-sgnated with the silicate from the siliceous water and were become whitenbsp;^^d soft. But there was one distinction to be observed, that the silicicnbsp;^cid in the wood which lay in the water had not become hard but hadnbsp;*'^tnained soft, while in the trees in the open air the hardening of thenbsp;''^ood containing the silica was advancing gradually from without inwards;nbsp;�onie trees were still soft and still showed the woody fibres, others werenbsp;qj-nbsp;nbsp;nbsp;nbsp;^be decayed woody fibre was replaced by a deposit of silica

cumstances couched in too general terms: � The silicified trees are therefore never produced under water, but in situ above the surface of the groundnbsp;by the constant supply of comparatively small quantities of siliceous waternbsp;from geysers or hot springs; the water rises in the wood by capillarynbsp;attraction and evaporates gradually in the open air.� Herr Kuntze hasnbsp;been kind enough to supply me with a small piece of fir-wood taken fromnbsp;one of the erect tree-stumps in Firehole Basin, which is of a spongy fibrousnbsp;texture, and of a brown colour inside but whitish on the outside, as describednbsp;above. From all the white parts I obtained, after destruction of thenbsp;organic substance by means of sulphuric acid, fusiform siliceous spiculae,nbsp;which looked somewhat corroded on the sides, and might stand for the castsnbsp;of the cells in which they originated. It seems very natural to explain innbsp;this way with Kuntze the origin of other similar fossil woods mentionednbsp;above, and there is still a possibility that with long continuance of thenbsp;process, resulting in more complete disappearance of the organic substancenbsp;of the membranes and the cementing together of the spiculae by thenbsp;solution of silicic acid penetrating between them, even dense compactnbsp;petrifaction may be produced. Renault ^ inclines to the view that thenbsp;majority of compact non-porous fir-woods originated in this way. I maynbsp;add that sections of some of these woods, that of Nicolia aegyptiaca, fornbsp;example, from the petrified forest at Cairo, lying before me, do in factnbsp;favour this view, which is also warmly supported by Schweinfurth^. Thenbsp;appearance is as if sharply defined cones answering to the cells of the woodnbsp;had been simply imbedded, fixed in a homogeneous matrix. All thingsnbsp;considered, it is very desirable that further investigation should be devotednbsp;to this subject, in which many points still require elucidation.

Lastly, there is a point of importance to be considered in connection with vegetable petrifactions. The process of petrifaction may begin at once whilenbsp;the stem is standing, or immediately after it has been laid in its place ofnbsp;deposit, but it may also be deferred to a much later time when the organicnbsp;remains are already converted into coal or are in process of conversion.nbsp;Unger� quotes as an instance of this the Miocene beds of lignite at Sagor innbsp;Carinthia, in which the seam is silicified in places to such an extent that thenbsp;work of mining has to be modified accordingly. Isolated pieces of silicifiednbsp;wood are everywhere of frequent occurrence in beds of lignite.

Local processes of petrifaction, though much more scattered and infrequent, are also observed in seams of coal; these appear generally to have taken place at a time when the seam had not yet attained its fullnbsp;development. The agent of petrifaction is either silicic acid or somenbsp;carbonate. The vegetable remains which form the seam are usually mixed

Up together in it in the state of confusion in which they were deposited, tiat they were in a soft and macerated condition is evident from theirnbsp;s'ng traversed in all directions by a luxuriant growth of fibres of Stigmaria,nbsp;und thus rendered useless for purposes of investigation. These phenomenanbsp;ure so extremely important for determining the anatomical character of thenbsp;'vegetable types of the Carboniferous formation, that it will be well to dv/ellnbsp;u little longer on them and on their occurrence.

Deposits of this kind are seldom found in the silicified state. Putting uside the hornstones of the district of Chemnitz, in which the state ofnbsp;preservation is not usually of the best, we have really nothing to mentionnbsp;ut the often-quoted dark brown siliceous fragments of Grand� Croix nearnbsp;Etienne, in which the parts of the plants are often so wonderfully well preserved, that Renault was able to determine from them a large number of thenbsp;rnost important facts relating to the structure of the leaves, flowers, and seedsnbsp;the inclosed plants. These stones are sharp-angled fragments of differentnbsp;sizes which have never been rolled, and are associated with a variety ofnbsp;lather objects to form a conglomerate. Many of them had been set free bynbsp;feathering and lay scattered over the fields; but they have now beennbsp;'Collected, as far as was possible, and brought to Paris, for there was reasonnbsp;lo fear that they would soon disappear altogether by being used for industrialnbsp;purposes. It is evident that they originally formed a connected stratumnbsp;f hich was broken up, its remains only being preserved in the conglomerate.

ue horizon of the strata from which these fragments came lies ac-^01 ding to Grand� Euryi between the coal-bearing strata of St. Etienne those of Rive de Gier; it belongs to the uppermost division of thenbsp;Coal-measures.

While the vegetable remains preserved in siderite are usually single speci-and are inclosed in geodes of clay iron-stone, calc-spar and dolomite uccur in many places as the petrifying agents of entire deposits, after thenbsp;Uianner of the siliceous fragments of Grand� Croix. We have known for somenbsp;pears 2 that certain seams in the great coal-fields of Lancashire and Yorkshirenbsp;Contain irregular roundish masses, large and small, which are the petrifiednbsp;Portions of the seam. The excellent researches of Williamson and Binneynbsp;'quot;^st essentially on specimens collected from these petrifactions near Halifaxnbsp;^ud Oldham. But the induration in the substance of these nodules, whichnbsp;Consist principally of calc-spar, is very much less than that shown by thenbsp;iceous pebbles of Autun in favourable circumstances. The seams whichnbsp;^titain them belong to the lowest beds of the Coal-measures of centralnbsp;gland ; they occur a short distance above the Millstone Grit, and alternatenbsp;^flh certain characteristic hard beds filled with Goniatites and Aviculopecten

and known as Gannister beds. Analyses are given in Binney�s work just cited. Herr Wedekind recently found nodules quite similar to the abovenbsp;on refuse-heaps at Zeche Vollmond near Langendreer, but consisting ofnbsp;dolomite, according to Weiss and not of calc-spar. The Fritz seam,nbsp;from which they seem to come, is unfortunately not worked at present;nbsp;but in its roof occur fossils similar to those of the Gannister beds, andnbsp;the vegetable remains found in the nodules are quite the same as thosenbsp;observed in England. Lastly, Stur^ refers to similar nodules, peat-sphaero-siderites, as he terms them, from the coal-seams of Witkowitz in Moravia andnbsp;from those of the upper Carboniferous deposits of Szekul in the Banat. Thenbsp;analyses of the latter show that siderite and calc-spar are present togethernbsp;in them in varying proportion.

In Fifeshire, north of Edinburgh, are coal-bearing strata which lie below the Millstone Grit, and are known by the collective name of thenbsp;Lower Burdie House Series. They correspond, according to Grand� Eury,nbsp;to the upper Kulmgrauwacke. In this series at Burntisland Grieve discovered beds, alternating with volcanic tuffs, which consist of crystallinenbsp;calc-spat and are filled with vegetable remains exactly in the manner ofnbsp;the petrified coals; these beds have supplied much material for Williamson�snbsp;researches.

Lastly, similar limestone beds occur at Laggan Bay in the Island of Arran on the west coast of Scotland, which are full of well-preserved remains,nbsp;and, like the Fifeshire beds, lie between diabase-tuffs. W�nsch^ tells us thatnbsp;a large number of stumps of trees, standing erect where they grew, werenbsp;discovered in his time in the compact black stone which takes a polish likenbsp;marble. The petrified outer portions of the stumps alone remain, the insidenbsp;having decayed and disappeared, and its place being taken usually by thenbsp;diabase-tuff which covers the whole deposit; but the interior also of a fewnbsp;stumps is filled with the petrifying material.

The changes which petrifactions undergo from exposure to external influences have been already noticed in more than one place. When theynbsp;are exposed to the air their organic substance is in most cases slowlynbsp;dissipated, and they may then have a transparent look and be colourless ornbsp;of a reddish hue, while when fresh from the place of deposit they are darknbsp;brown or almost black. Water trickling over them naturally expedites thenbsp;process, and may even accomplish it before they have been exposed. Thisnbsp;change produced by atmospheric influences is particularly well shown in thenbsp;case of the silicified woods of the lignites of the districts of Meissner andnbsp;Zobten in Silesia, which when exposed to the air become encased in anbsp;whitish rind. The organic substance may also be removed from petrifactions

strong heat, which usually causes the sections to crack and lose their colour, and often become opaque and of a whitish hue. These effects arenbsp;produced also in nature in places where the deposits have been traversednbsp;^y intrusive rocks. Bleached wood-opals of this kind are common in thenbsp;�Neighbourhood of the Siebengebirge and of the eruptive trachyte of Ober-cassel and Tokay k Exposure to rain sometimes completely removes thenbsp;petrifying material from fossils in calc-spar, and then nothing is left in thenbsp;stone but the cavity which held the fossil, and in it a few remains of organicnbsp;substance. The wall of the cavity is often covered with crystals of calc-�par. The well-known nodules of the refuse-heaps at the copper minesnbsp;of Ilmenau, which contain fishes and small branches of Conifers, have mostnbsp;C'f them unfortunately suffered from this mode of destruction

Somewhat better results have been obtained from investigations into Algae. Of these a large number of forms have been described whichnbsp;either doubtful or of no value to the botanist, and which will be brieflynbsp;j^oticed at a later period in this work; but a certain number of groups maynbsp;0 Selected for mention here, since their relations to recent forms can benbsp;established with more or less certainty. There are first the Diatomaceae,nbsp;la �¹bceous valves occur in Tertiary and Quaternary deposits in suchnbsp;thnbsp;nbsp;nbsp;nbsp;and so entirely or almost entirely free from admixture, that

ey form layers several metres thick of a loose white substance known as 1 n-powder, which has been largely employed of late years for technicalnbsp;P�Jrposes. The polishing slate of Bilin in Bohemia and of Habichtswaldnbsp;Cassel, a white stratified rock of Miocene age, is almost entirely com-P'^sed of these Diatom-valves. Each separate deposit of the kind usuallynbsp;a large number of species, but these are almost always so disposednbsp;'� one species or a few form the chief mass of the deposit, and the restnbsp;^^0 isolated and disseminated through it. Ehrenberg'', to whom we owenbsp;niost searching investigations into fossil Diatoms, states for examplenbsp;Gallionella distans and Podosphenia nana in alternate layers formnbsp;the entire mass of the polishing slate of Bilin, that Eunotiae and

are to a great extent composed of Naviculae. Ehren-has further shown that a large number of Diatoms are found also in jj. ^PP^rmost beds of the Chalk, and gives a list of them�; among themnbsp;othnbsp;nbsp;nbsp;nbsp;Gallionella, Coscinodiscus, Triceratium, Amphitetras, and

Q sis. Most of these forms have been found only in the Chalk marls of Caltanisetta, and Zante, but a few occur in company with Polythala-in the true white writing-chalk, for example, Gallionella aurichalcea,nbsp;p^^Silaria rhabdosoma, and Fr. striolata at R�gen and Gravesend.

nre even identical with recent species, and that the percentage of 6s not now known to be living diminishes in the strata from belownbsp;Ids. Even in the Chalk we meet with several species still in existence.nbsp;C)iatoni-beds seem to have been formed both in fresh and salt water;

fhe beds of tripoli-powder and Diatom-earth were formed in fresh b the Chalk-marls in salt water; the latter deposits contain forms

therefore is mistaken when he says that we search in vain for ^^^^cillariae in the Upper Chalk. Ehrenberg� has already shown that allnbsp;the^^nbsp;nbsp;nbsp;nbsp;down to the Chalk belong to still living genera, that many of

nbsp;nbsp;nbsp;^ Ehrenberg (1) and (2).nbsp;nbsp;nbsp;nbsp;� Ehrenberg (2), p. 119.

� Ehrgjj�^ ^^cillariaceen in Encyclop. d. Natw., Handb. d. Botanik von A. Schenk, ii, p. 409 (1882).

II.

It lies in the nature of the case that fossil Thallophytes should as a rule be objects of very small importance to the botanist. There arenbsp;indeed groups among the Thallophytes to which this statement does notnbsp;apply, those chiefly in which the membranes were calcified while they werenbsp;still living, and which are therefore found in an unusually perfect state ofnbsp;preservation. Schimper gives us a long list of Fungi and Lichens whichnbsp;have been described by older writers. Where these are not merely spotsnbsp;on leaves, but actual Pyrenomycetes, Discomycetes, and Basidiomycetesnbsp;growing on leaves or on pieces of fossil wood, they still have no value exceptnbsp;as showing what was probable without them, namely, that Fungi formednbsp;a part of the ancient floras. Where Polyporei and Lenzites occur, as innbsp;the brown coals, it is not surprising that we should also find silicified woodsnbsp;which have been half destroyed by their mycelia. Such mycelia from woodnbsp;of the Tertiary era have been described by Unger� under the generic namenbsp;Nyctomyces. That there were Fungi in the older formations also isnbsp;proved by the fragments of thallus with local bladder-like swellings, whichnbsp;are occasionally found in the tissue of stems of Lepidodendron, and whichnbsp;have been figured by Williamson ^ under the name of Peronosporites anti-quarius. Worth. Smith. Similar objects have been mentioned by othernbsp;writers also, for example by Renault and Bertrand under the name ofnbsp;Grilletia Sphaerospermii from seeds of the period of the Coal-measuresnbsp;found in the siliceous fragments of Grand� Croix. A form described bynbsp;Ludwig'� from coal-seams of the Urals as Gasteromyces farinosus maynbsp;be nothing more than an aggregate of spores and spore-tetrads of somenbsp;archegoniate plant. That Bacteria destroyed the substance of dead plantsnbsp;during the period of the Coal-measures, as they do at the present day, isnbsp;rendered extremely probable by the researches of van Tieghem�, who hasnbsp;shown that the macerated vegetable fragments in the pebbles of Grand�nbsp;Croix exhibit the same progressive demolition of the cell-wall which is

� Unger (1). nbsp;nbsp;nbsp;� Williamson (1), xi, t. 48, fif. 36, 37 ; t. 54, ff. 28-31.nbsp;nbsp;nbsp;nbsp;= Renault (3)

(Renault and Bertrand). nbsp;nbsp;nbsp;Ludwig (3).nbsp;nbsp;nbsp;nbsp;�� van Tieghem (1).

which, at the present time at least, live only in the sea, and are entirely wanting in the other beds. It is very remarkable that absolutely no plantsnbsp;of this group have been discovered in the formations below the Senonian.nbsp;It is true that Castracane ^ obtained from the ash of English coal at Romenbsp;eight species of common fresh-water Diatoms; but the statement has nevernbsp;been confirmed, and though the author assures us that he adopted everynbsp;measure of precaution, it must be regarded with the greatest suspicion,nbsp;especially since Williamson^ has failed to find any such forms after examining coal from twenty-two different seams in order to determine thenbsp;point. Pfitzer in the article just cited has expressed the opinion that thenbsp;group made its appearance for the first time in the Upper Chalk. Thisnbsp;appears to me on many grounds highly improbable. It is importantnbsp;to consider whether renewed investigations would not result in further interesting discoveries, for no one since Ehrenberg seems to have taken thenbsp;subject seriously in hand.

The only organic remains from the older formations, which have been supposed to belong to Uiatomaceae, are the forms of the genus Bactrylliumnbsp;which have been studied chiefly by Heer These are small red-shaped bodiesnbsp;of very peculiar and doubtful character, rounded or almost rectangularly cutnbsp;off at both extremities and pressed quite flat, each having a single furrownbsp;on the broader side, or two furrows separated by an intervening cushion.nbsp;Their rather thick wall incloses, according to Heer, a cavity which is fillednbsp;with the stony mass. In some forms a transverse striation is seen on thenbsp;broader surface on both sides of the central furrow. The largest species,nbsp;such as B. Schmidii, Heer, are as much as four millimetres in length. Thenbsp;comparison with Diatomaceae rests entirely on the external appearance; thenbsp;furrow in the middle was supposed to correspond to the division betweennbsp;the valves, and the transverse striation to be analogous with the sculpturingsnbsp;upon them. The vegetable nature of these organisms is not certainly ascertained, and further examination of them is desirable. Bactryllia are foundnbsp;in the Keuper of the Alps and of the North of Switzerland, and are particularly plentiful in the Sankt Cassian beds, where they lie massednbsp;together in the slates. According to .Schimper* they also occur in thenbsp;Muschelkalk near Heidelberg.

We are acquainted with fossil remains from several groups of the series of Chlorosporeae. The Characeae are represented in the Quaternary andnbsp;Tertiary formations by a considerable number of species, which, as far asnbsp;we are able to determine, agree- entirely with recent forms. A number ofnbsp;species are known also from older formations, Chara Jaccardi, for example,nbsp;from the Lower Chalk of the Canton of Neufchatel and Ch. Bleicheri from

^ Williamson i l), x, p. 519. nbsp;nbsp;nbsp;'�* Ileer (2) and (3).nbsp;nbsp;nbsp;nbsp;^ Zittel (1).

Middle Oolites (Oxford beds) of France. It is only in rare cases that e thallus of the Charas is so preserved as to show its form; it is usuallynbsp;�hen up into small tubular fragments. The more perfect state occursnbsp;in the most recent fresh-water deposits, for instance in the tuffs ofnbsp;3-nnstadt and Weimar, in which our common species Chara hispida isnbsp;ound incrusted, as if by a recent calcareous spring. In the case of allnbsp;_ forms we have nothing but the remains of the oospores with theirnbsp;and in these the calcareous shell only has been preserved; the crownnbsp;always wanting. The fossil specimens show an orifice which answersnbsp;^ the point of attachment; the pedicel-cell not having been calcifiednbsp;disappeared.

recently been shown by Munier Chalmas^ that an entire group fossil organisms hitherto placed among Foramiiiiferae is connected withnbsp;th^ ^^*^dy of Dasycladeae, and especially with those members of it in whichnbsp;Membranes are calcified, namely the genera Cymopolia and Neomeris.nbsp;^^lortunately there are several serious difficulties in the way of an exactnbsp;full description of this group. The recent species belonging to it arenbsp;�dll little known,�I have had a monograph on the subject for some time innbsp;P^'^Paration,�and Munier Chalmas has not yet published his elaboratenbsp;'Investigations into the fossil forms; in his preliminary communication he hasnbsp;amp;'ven the names of many genera, but no descriptions of any of them. Therenbsp;alsonbsp;Polytnbsp;G�

J^oibel Thyrsoporella. I satisfied myself on this point when Munier 3-Jtnas was kind enough to explain a number of his genera to me.

The unicellular thallus of the recent genus Cymopolia (Fig. 2) has an exceedingly complicated structure. It forms a tuft of branches which branch

it nbsp;nbsp;nbsp;whorls of lateral branches ; its lumen also is uninterrupted, and

Th nbsp;nbsp;nbsp;^ slight stricture at the joints between the calcified members.

� membrane of this central tube is of great thickness and stratified, and Ho deposit of lime in any part of its substance. The lateral branches

differ from one another according as they proceed from the members or from the joints. Their whorls are closely crowded together, more closelynbsp;in the joints than in the members; the lumina of all their ramificationsnbsp;traverse the thick membrane of the central tube like narrow pipes andnbsp;communicate with its cavity. The whorls which are upon the joints consistnbsp;of short branches of simple cylindrical form directed obliquely upwards,nbsp;and becoming successively shorter from below upwards. At the apex of

each branch is a broad scar, on which one of the branched hairsnbsp;once stood which, as we havenbsp;already explained, are attachednbsp;to the younger parts of the thal-lus. These hairs are developednbsp;only on the whorls of branchesnbsp;which belong to the joints.

Fig. 2. Cymopolia barbata, from specimens in spirit in the collection at Gottingen, which were obtained by Askenasy innbsp;Grand Canary. A showing the habit of a small piece of thenbsp;plant. B longitudinal section of part of the same with one of thenbsp;non-calcified places of articulation of the thallus. At thisnbsp;place the lateral members of the whorl are not branched, andnbsp;terminate in a scar which once bore one of the branched hairsnbsp;of the tuft; the hairs forming the normal terminal tuft are stillnbsp;to be seen in A attached to the youngest parts of the thallus.nbsp;Where the members are calcified, all the branches of a whorlnbsp;bear a terminal sporangium and from four to six peripheralnbsp;branches of the second order, which swell into the shape ofnbsp;a bladder at the apex. These bladder-like swellings, connectednbsp;with one another by their sides and not calcified, form a regularnbsp;outer rind, which collap.ses in drying and is therefore wantingnbsp;in fossil specimens of Polytrypa. The limits within which thenbsp;calcification is confined is indicated by dark shading. A slightlynbsp;magnified.

Each branch of a whorl, standing out at right angles tonbsp;the thallus, ends inside the calcified members in a bladder-likenbsp;swelling, and bears above this anbsp;large ovoid sporangium on anbsp;small and very short stalk. Fournbsp;to six branches of the secondnbsp;order, of exactly the same shapenbsp;as those of the first, spring fromnbsp;the apical surface of the primarynbsp;branch and surround the sporangium. Their bladder-like extremities unite above the sporangium, and laterally with those ofnbsp;the adjoining system of lateralnbsp;branches, and become prettynbsp;firmly attached to one another.nbsp;In this way a continuous cortical layer is formed, which when seen from without appears to consistnbsp;merely of single separate cells. The broad gap which remains beneath thisnbsp;rind between the filamentous members of the first and second order is fillednbsp;with a mucilage formed from the swelling up of the outer layer of theirnbsp;membranes, and it is this only which being thoroughly calcified becomesnbsp;thereby hard and brittle. The inner membranous layers which adjoin thenbsp;lumen and are not disorganised continue entirely free from lime. Boundednbsp;by these membranes, the cell-lumina of the verticillate branches and of thenbsp;sporangia are seen as cavities and canals full of protoplasm traversing the

ca-lcareous mass, which thus forms a thick hollow cylinder about the axile lube. The exterior terminations of the members of the second order, whichnbsp;uoheie laterally and form a rind, are never calcified ; it may be presumednbsp;at they are chiefly concerned in the work of assimilation, and they causenbsp;e prettily areolate appearance of the surface. Fig. % on page 38, which isnbsp;rawn from nature, will serve to illustrate this description.

Among fossil forms the genus Polytrypa, Mun. Chaim, has absolutely � same structure as Cymopolia, and therefore Munier Chalmas mostnbsp;P�operly unites the two genera. Polytrypa, like most of the forms whichnbsp;quot;'u are about to consider, is found in the sands of the Eocene deposits in thenbsp;�^uighbourhood of Paris. Only the calcified parts of course are preserved,nbsp;^ud the whole plant is therefore broken up into its several members by thenbsp;^appearance of the portions forming the joints. Each member shows anbsp;oad central canal (the main axis) with secondary verticillate systems ofnbsp;canals proceeding from it and passing through its calcareous ring; thenbsp;�atiddle branches of the whorls end of course blindly in the cavities of thenbsp;sporangia, while the lateral branches, traversing the whole breadth of thenbsp;�-alcareous matter as slender canals, are open to the outside, where theynbsp;^Ppear in the form of circular pores. They are thus open externally,nbsp;^uause the bladder-shaped outer extremities of the cells not being calcified

The type of G�mbel�s genus Haploporella is Carpenter�s ^ Dactylopora ba^^^� u form which is said to be still living in tropical seas, and which isnbsp;sed on the recent genus Neomeris, Harv., as I shall presently endeavournbsp;show. It is left by Munier Chalmas with Polytrypa-Cymopolia, andnbsp;^presents the type of the section Decaisnella, which, as I have said, I amnbsp;�f*uble to distinguish from Neomeris. The thallus of Neomeris is simplenbsp;^�^d unbranched, and answers to a single calcified member of Cymopolianbsp;has elongated by apical growth and may ultimately attain consider-^ ^ dimensions. The whorls of branches are also like those of Cymopolia,nbsp;tiever bear more than two branches of the second order beside thenbsp;Poranginm, and these always occupy the median position. Moreover, thenbsp;'ncation is less copious and never results in the formation of a homo-S^neous cylinder inclosing all the lateral branch-systems ; it is in fact onlynbsp;^�und the sporangium and round the swollen extremity of the branch ofnbsp;first order which bears it, that it is developed to any considerablenbsp;quot;^tent and that it forms a crust. Hence it is that these parts only arenbsp;erved; the slight laminae of lime which clothe the branches of thenbsp;nd order were not firm enough to resist disintegration. The wholenbsp;in the fossil state has separated into a countless number ofnbsp;pieces, each of which usually conceals a sporangium. A single canal,

opening to the outside and circular in the transverse section, leads naturally to the cavity of its own sporangium. Not unfrequently with increase innbsp;thickness of the calcareous rind several sporangia belonging to one whorlnbsp;are caked together into a broader body of the same kind inclosing severalnbsp;cavities, each one of which is provided with its conducting canal. Thenbsp;figures in G�mbel�s� work illustrate these points. When calcareous cases ofnbsp;this kind were found in the sea-sand, and their internal cavity (the sporangium) was seen to be filled with protoplasm, it was not unnatural that theynbsp;should have been taken for still living Foraminifera.

But there are many genera besides those which have now been described, chiefly in Eocene, but also in Oligocene and Miocene deposits.

Fig. 3. Uteria Encrinella, Mich. B Surface-view of a member seennbsp;from above, and showing thenbsp;lumen of the main axis as a central tubular cavity. .lt;4 longitudinalnbsp;somewhat lateral fracture of anbsp;member, showing on the wall ofnbsp;the inner calcified tube of thenbsp;main axis two whorls of pores,nbsp;which answer to the points ofnbsp;attachment of the lateral branch-whorls. For each of these whorlsnbsp;two whorls are seen in regularnbsp;order on the outer calcareous shell.nbsp;Each branch therefore of the firstnbsp;order bears two whorls of thenbsp;second order in the median position.

These differ much in character, in some cases so essentially that their mutual relations could onlynbsp;be thoroughly explained in a monograph. Stillnbsp;the structure of some of them may be made intelligible with the aid of certain unimportantnbsp;assumptions, and be referred to the type ofnbsp;Cymopolia. I mention as an example of thesenbsp;Uteria Encrinella, Mich.^, a form common in sandsnbsp;of the Lower Eocene formation, those for examplenbsp;of Herouval and Guise la Mothe near Paris. Theirnbsp;small members are flattened and barrel-shaped,nbsp;and form hollow rings bounded above and belownbsp;by plane surfaces rippled in radiating lines. Eachnbsp;of these may answer to a member of the thallus,nbsp;in which the wall of the main axis is stronglynbsp;calcified, and in this respect is the opposite ofnbsp;Cymopolia. Nothing remains of the verticillatenbsp;branches of the first order except the pores bynbsp;which their lumen communicated through thenbsp;calcareous deposit with the main tube. Thenbsp;sporangia also which were not calcified and thenbsp;basal parts of the branches of the second order have entirely disappeared. The outer calcareous rind of the member, pierced by honeycomb-like openings, must be supposed to answer to a localised zonenbsp;of calcification, which was developed close beneath the rind formednbsp;by the bladder-like extremities of these members of the second order.nbsp;The lateral walls of the branch-systems at the terminal surfaces of eachnbsp;barrel are also calcified. From the position on the main axile tube ofnbsp;the pores which, corresponding with the branches of the first order, mark onnbsp;the peripheral calcareous rind the lines of communication of these with.

I ose of the second order, it may further be concluded that the latter, * e those of Neomeris, were as a rule only two in number and occupiednbsp;the median position, for two pores in the peripheral calcareous layernbsp;answer to a ring of pores on the axile tube. But this is not observed withnbsp;perfect regularity in all cases. More searching investigation will probablynbsp;show the existence of a variety of specific differences.

Among forms of more complicated .structure are some which, like fftelina, Mun. Chaim, and Terquemella, Mun. Chaim., are undoubtedlynbsp;^hied to the recent genus Bornetella, Mun. Chaim. But since the remark-^hle structure of Bornetella has nowhere been as yet fully described, and anbsp;'Monograph of the entire group cannot be introduced into this place, anbsp;�^�nute description of the fossil genera is at the present moment scarcelynbsp;Possible. There are also genera in which the construction is still quite unexplained ; one of these

a form of very fi'e-fiuent occurrence, Thyr-�oporellacribrosa^, Giim-hol (Dactylopora, Mun. ^halm.), which I havenbsp;had the opportunity ofnbsp;examining in manyspeci-

^ens.

Some genera are of '^ore simple structure,nbsp;it is not yet quitenbsp;^srtain that they belongnbsp;the class of which wenbsp;speaking. They arenbsp;found in the Trias, and

Fig. 4. A transver.se section of a piece of .stone from the Keuper of the Alps of Southern Tyrol pierced with Diploporae. B interior of anbsp;Diplopora from Esino. C surface.view of Gyroporella vesiculifera fromnbsp;Inzino in Lombardy. D longitudinal fracture of the same from Sannbsp;Michele on the lake of Garda; the cast which fills the axile tube is preserved in the lower part of the figure. E surface of detached cast of thenbsp;main axis of the same species. A twice the natural size. From Zittel�snbsp;Handbook.

�ccui- especially in the ^^outhern Alps, wherenbsp;form rocky massesnbsp;great thickness ^

rnode of preservation is different from the above, since all their cavities usually filled with the material of the rock in which they lie; and if anbsp;still remains open in the wide tube of the main axis, its walls arenbsp;^ ^hy lined with crystals closely crowded together. Diplopora annulata,nbsp;and its allies (Fig. 4 A, B), which are peculiar to the Muschelkalknbsp;^ Alps and to the Lower Keuper (Mendola dolomite, Wettersteinkalk),nbsp;� a long cylindrical obscurely segmented thallus with a dome-shaped

apex, which however is seldom preserved. The central axile tube is of extraordinary width, and is surrounded by numerous crowded rings ornbsp;whorls of lateral canals, which traverse the rind and have the passage opennbsp;to the outside. A similar construction is seen in Gyroporella vesiculifera ^nbsp;(Fig. 4 C-E), which belongs to the main dolomite of the Upper Keuper andnbsp;occurs chiefly and abundantly in the Alps of Lombardy; but here the lateralnbsp;canals, forming less distinct rings, are closed on the outer side by a smallnbsp;and somewhat convex plate. We can scarcely be wrong in assuming thatnbsp;this difference arose in a construction originally alike in both cases, innbsp;consequence of the apical membrane of the branch being sometimes calcifiednbsp;and sometimes remaining unaltered. There is therefore an essential difference between the Tertiary forms first considered and these forms from thenbsp;Trias; the latter, in place of complicated lateral branch-systems producingnbsp;sporangia, have only whorls of short simple members, which are eithernbsp;cylindrical or somewhat swollen and enlarged. Whether these membersnbsp;developed directly into sporangia by formation of septa between them andnbsp;the lumen of the main axis, or in certain circumstances produced at theirnbsp;extremity free sporangia which did not become calcified, we do not know.nbsp;If the latter was the case, then no fruiting specimens have yet been observed,nbsp;for these would show the scars of the sporangia. In the former case rvenbsp;should have a simplification of the type of Dasycladeae, and this wouldnbsp;present no difficulty from the algological point of view. The Cretaceousnbsp;genus Munieria, Hantken, which forms beds of stone near Bakony innbsp;Hungary and has been described by Deecke will probably be united tonbsp;Diplopora and Gyroporella ; it requires further study.

Lastly, in Triploporella Fraasii, Steinmann, from the Turonian Chalk of the Lebanon, we have a form, which seems to be intermediate between thenbsp;two groups above mentioned. It has been described by Steinmann andnbsp;externally it exactly resembles Diplopora, but each simple shortly cylindrical branch in a whorl has at its apex three small almost globular branchesnbsp;of the second order. As to the meaning of these branches, since there is nonbsp;indication that there was once a sporangium between them, we can only saynbsp;what was said of those of Gyroporella.

A few fossil genera are placed by Munier Chalmas in the group of Acetabularieae, the nearest allies of Dasycladeae. Of these I know onlynbsp;Acicularia, d�Archiac and Briardina, Mun. Chaim., the latter through thenbsp;kindness of Munier, who himself demonstrated it to me. We find a varietynbsp;of forms figured in Carpenter ^ under the name Acicularia ; of these, figuresnbsp;27 and 31 may represent Munier�s Acicularia, figures 28-30 another genus,nbsp;perhaps Orioporella. I question much whether figure 32 belongs to this group

' Giimbel (1). nbsp;nbsp;nbsp;� Deecke (1).nbsp;nbsp;nbsp;nbsp;^ Steinmann (1).nbsp;nbsp;nbsp;nbsp;* Carpenter (1), t. ii, ff. 27-32.

ese forms in a fragmentary state may look very like Dactyloporidae, ut they differ from them in the absence of the central canal; they arenbsp;pointed or flattened conical bodies, sometimes united laterally into bundlesnbsp;^nd becoming broader and wedge-shaped in front, and are supposed tonbsp;*�6piesent the separate rays of the cap of Acetabularia or Polyphysa. Theynbsp;^ontain a number of conical cavities opening to the outside, which mustnbsp;inclosed the zoosporangia formed in the rays. Strange to say, theynbsp;^^0 completely filled with calcareous matter, which is never the case innbsp;Accent forms.

^ It usually happens that as soon as ever a doubtful group has by a lucky *t found a secure place in the system, attempts are at once made to bringnbsp;. �^^ies of enigmatical forms into connection with it, and this has been donenbsp;the present case. How far there is any good ground for these attemptsnbsp;^ question which cannot be minutely considered in this place; we mustnbsp;^^it till we have obtained a broader basis for our knowledge of the fossilnbsp;^^ycladeae, now that we have ascertained their position. Steinmannnbsp;^uposes to unite with them Coelotrochium Decheni, Schl�t. from thenbsp;^Pper Devonian beds of Gerolstein, Cyclocrinus from the Silurian strata,nbsp;�ceptaculites also and its allies, and lastly the Jurassic Goniolina. Thenbsp;form has, on the other hand, been quite recently compared by Sa-Poftai with Williamsonia, and been supposed to be the fructification of anbsp;^^'oangiosperm, an Angiosperm in statu jiascendi. Deecke ^ describes thenbsp;^vonian Sycidium, Sandb. as belonging to Dasycladeae, and Schliiter�nbsp;a number of other forms which have been taken into consideration,nbsp;isnbsp;nbsp;nbsp;nbsp;genus Penicillus, Lamk. (Espera, Dene), a form of Chlorosporeae,

� known to occupy a doubtful position in the system and to require re-^ewed examination. The unicellular thallus consists of a tuft of dichoto-^ously branched filaments divided by constrictions into ovoid or cylindrical ^guients, which look like cells but communicate freely with one another,nbsp;n stout solid cell-membrane becomes calcified except at the places ofnbsp;Pparent articulation answering to the constrictions, but the incrustation

the

kiittle stem. From the younger portions of the filaments which are not yet ^S-ked together the calcareous rind readily breaks away in tubular portionsnbsp;Corresponding to the members of the plant, or into fragments of the same ,nbsp;Ike substance of the rind is not uniform, but is traversed by round or ir-'^cgularly shaped vacant spaces irregularly disposed and ciowded together,nbsp;sometimes running into one another. Why calcification was interrupted

in the fossil state belong to the family of Corallineae and to the section Lithothamniae, which are almost the sole components of certain deposits ofnbsp;former ages, as they now form extensive beds at the bottom of the sea. Itnbsp;IS extremely difficult to distinguish the species in the living representativesnbsp;of this group, and it may readily be conceived that the difficulty of dealingnbsp;quot;'dh the fossil forms is still greater. We shall do well to follow Unger ^ innbsp;fhis matter, and put them all together as Lithothamnium ramosissimum.nbsp;The only proof that in these nodular calcareous forms with shrub-likenbsp;franching we have really to do with Lithothamnium is, as G�mbel ^ shows,nbsp;the presence of the characteristic structure. If we find that a body of thisnbsp;kind Consists of layers of rectangular cells lying one on another as concentric shells, there is always a possibility of confounding them with familiesnbsp;nf Bryozoa, at least when the outer surface is not in a perfect state of preservation. But in that case we have an excellent aid to discrimination in*nbsp;fbe fructifications, which in the Lithothamniae are formed in great numbersnbsp;ky later overarching of adjacent tissue, and are seen in the substance of thenbsp;lhallus

as ovoid cavities into which the sporophore projects on the under Side in the form of a small cone. Such undoubted Lithothamniae arenbsp;S-bundant throughout the series of Tertiary deposits, and in some localitiesnbsp;'�key form almost the entii'e material of systems of layers of no inconsider-^kle thickness, as for example in the Lower Eocene strata of Toin in thenbsp;department of Ari�ge, and in the Pliocene deposits of the Rupe Atenea atnbsp;^kgenti near Syracuse, where they are quarried in the famous Latomiae.

'^ey compose also the limestone of Leitha near Vienna, and the granite-^^I'ble of the Nummulitic rocks. They occur also in the Senonian of the etersberg near Maestricht, in the same formation at Les Martigues nearnbsp;Marseilles, and in the pisolite limestones of Paris, and one species has beennbsp;Milearly identified from the zone of Ammonites bimammatus in the Jura,nbsp;^iiiall shrubs and bushes of the same kind and of thoroughly similar habitnbsp;also found in older formations, but as the structure has not been pre-�^rved they cannot be certainly distinguished from concretions of inorganicnbsp;I have found such objects repeatedly in the Muschelkalk of thenbsp;ainberg near Gottingen, but have never been able to detect any remainsnbsp;structure in my sections. Lastly, the Siluro-devonian genus Nemato-Pkycus may be mentioned in this connection, which from its anatomicalnbsp;structure may perhaps belong to Fucaceae ; but as we shall have to returnnbsp;jt in speaking of coniferous woods, we will reserve any further descriptionnbsp;k for that place.

j Besides the groups of Algae hitherto mentioned, there still remains a 'quot;Se number of forms from all the formations, from the Quaternary back

at these spots is not apparent; there are no emergences, such as hairs for example, which could have passed through the deposited matter. Thenbsp;branching is always in regular dichotomies, which commence in each casenbsp;at the upper end of one of the cell-like members while still young.

Munier Chalmas \ in a recent publication, has sought to identify Peni-cillus with the genus Ovulites, Lamk., which is common in the sands of the Eocene formation, especially round Paris, and was formerly classed withnbsp;Foraminiferae. Though further and extended investigation may be necessary to establish the justness of this comparison, as will be shown in thenbsp;remarks which follow, yet it must be regarded as a very happy and invitingnbsp;suggestion.

The calcareous shells as preserved in Ovulites are ovoid or fusiform, and pierced by a large hole at both extremities; sometimes there are twonbsp;holes beside one another at one extremity. The shells are everywhere verynbsp;thin and fragile; their surface, which appears smooth to the unaided eye, isnbsp;seen under high magnifying power to be broken by a large number ofnbsp;steep-sided dot-like pores, which are surrounded by fine lines inclosingnbsp;polygonal spaces. Putting aside the thinness of the shell and the irregularnbsp;distribution of the pores, we have here a structure which might also be verynbsp;well left behind by a plant like Cymopolia, especially if the calcification innbsp;it was continued only to the wall of the central tube ; for the wall-like sidesnbsp;of the pores, thin as they are, favour the view that they represent the luminanbsp;of lateral members which have themselves disappeared. Munier Chalmasnbsp;indeed, and Steinmann^ also, are of opinion that there were lateral membersnbsp;of the kind in Penicillus also, answering to the vacant spaces in the calcareous shell. But this is a mistake. Moreover, these spaces in Penicillusnbsp;have not the sharply defined boundaries of those of Ovulites, their shape isnbsp;more irregular, and several of them often run together into irregular figures.nbsp;There is also no appearance in Penicillus of the reticulated design characteristic of the shell of Ovulites. The occurrence of members with two axilenbsp;perforations at the upper extremity certainly shows that the thallus of Penicillus was dichotomously branched; but these holes must also be found innbsp;plants of the nature of Cymopolia, if the bridge of membrane lying in thenbsp;bifurcation of the branches and terminating the lower member is calcified.nbsp;If it is not, the two round holes will be confluent into one ovoid hole, as innbsp;Penicillus. From all this I should conclude that we have in Ovulites members of a calcareous Alga, which may be compared with the group whichnbsp;we are considering, but whose position in the system cannot be finallynbsp;determined without further investigation.

to the Lower Silurian, which have been described under an abundance of generic names ; but they have virtually no interest for the botanist, becausenbsp;there is no immediate possibility of profitable comparison with known algalnbsp;types. We may perhaps be able at some future time to pick out a typenbsp;here and there out of this hopeless chaos, but it is scarcely possible that wenbsp;shall ever attain to a better position as regards the remainder. We mustnbsp;necessarily be always dependent on characters derived from external form,nbsp;and these in the case of the Algae prove only too little; we can scarcelynbsp;hope to penetrate to the inner structure of the fructification, which cannbsp;alone determine the affinity. And, to meet an objection which may benbsp;expected from the palaeontologists, I will add at once that I should notnbsp;hesitate to say the same of the Coniferae, for instance, if we had nothingnbsp;left of them but the impressions of the leaves ; but there we are better off,nbsp;for cones, wood, and fi'agments showing anatomical structure have beennbsp;preserved as so many points of support for the conclusions, by which we cannbsp;be continually testing the degree of probability to be assigned to new conquests. What mistakes may be made without the aid of such objects isnbsp;shown by the number of impressions of Conifers, which are explained bynbsp;older authors, by Brongniart for example, as Zonarites digitatus, variousnbsp;Caulerpitae and other Algae.

This problematical character of the remains could not well escape the attention even of the earlier observers, who soon accustomed themselves tonbsp;describe everything as an Alga which could not be disposed of elsewhere.nbsp;Hall�s^ remark is much to the point: �It has been the habit to refer tonbsp;vegetable origin all those fossil bodies of the older strata which have innbsp;their general aspect, their habit or mode of growth some similarity to plants,nbsp;and in which no organic structure can be detected beyond sometimes thenbsp;external markings.� That so large a proportion of �Algae� were brought tonbsp;light from the oldest formations was entirely due to the fact, that there wasnbsp;a more eager search for organic remains there than elsewhere to meet thenbsp;requirements of geological investigation. In recent times the later formations also have been diligently examined for the same purpose; but in thenbsp;Silurian and Devonian deposits every bit of raised surface however shapelessnbsp;was named in this way, as may be seen from the figures of the genusnbsp;Eophyton, Torell, to be found in Saporta^. From such an extension of thenbsp;idea of a fossil Alga a speedy reaction was inevitable, and attempts werenbsp;made to show that many of the objects described as Algae were casts ofnbsp;the tracks of animals, like the well-known impressions of Chirotherium fromnbsp;the Bunter Sandstein, and that others again were merely of inorganic origin.nbsp;This divergence of views has recently given rise to a lively discussion

^0 allows that there are some fossil Algae, makes the presence of a ^oal the ultimate criterion, and roundly denies the algal nature ofnbsp;i ^ where that is not found. It appears from the remarks in thenbsp;knnbsp;nbsp;nbsp;nbsp;chapter to the present work, that this cannot be admitted. We

the coal may entirely disappear in the course of time from ro b that are undoubtedly organic, if they are deposited in a porousnbsp;Wh� ' Moreover, Nathorst refuses to allow that any of the remainsnbsp;Ve �ccur in half-relief on the surface of slabs of stone belong to thenbsp;kingdom. Saporta'^, as has been already stated in the Intro-�cii, attacks this doctrine on good grounds and with more than usual

earnestness.

The whole question in dispute is not one in which the botanist is Co 1 ^ **iterested, for even remains, which being provided with strips ofnbsp;are allowed by both sides to be Algae, such for example as manynbsp;Qj. �^ens from the Eocene beds of Mte Bolca and from the Uppernbsp;jjj 'S^^cne (Aquitanian) beds of Sotzka and Radoboj, are of no value tonbsp;except in the few cases in which the external form is so well marked

Q^^rople, with the Cystoseiritae of Radoboj. There may possibly be remains true Algae among specimens obtained from other formation.s, but nonbsp;^ of this can be produced, and we cannot thei-efore at present attemptnbsp;^ exact determination of the family to which they belong.

On the other hand, it has been shown in many cases that supposed 9-ins of Algae are of a totally different nature. Of this we have anbsp;�^^^naber of striking instances, for which we are chiefly indebted to Nathorst,nbsp;^P^rt from mistakes such as that made by Saporta�, who confoundednbsp;.nbsp;nbsp;nbsp;nbsp;�'''cd Oyster-shells with Algae, as in the case of Conchyophycus Mar-

^'Snyanus ^ckn,

Passi:

the observations of several of the older writers, Emmons, Hancock, f^awson and others, who had explained certain of the supposed Algae asnbsp;'^iprints of the tracks of animals, Nathorst tried the experiment of obtainingnbsp;^��acks of the kind on prepared ground and then taking casts of them mnbsp;plaster of Paris. A variety of imprints were thus procured in half-relief.

which corresponded more or less perfectly with certain supposed Alga-types. In some cases the result was striking. Eophyton^ Torell was produced with the greatest ease by passing bits of Algae and parts ofnbsp;animals over soft mud. The casts of tracks of a crab, Corophium longicorne,nbsp;gave a figure which answers so exactly to the Silurian and Carboniferousnbsp;genus Crossochorda and also to Gyrochorda from the Tertiary strata of thenbsp;Jura, that Saporta^ himself has consented to remove these genera from thenbsp;Algae. Precisely similar tracks, according to Etheridge and Nicholson, arenbsp;also made by Purpura lapillus Williamson � again took casts in the samenbsp;way of the furrows left behind by the retreating tide on the shore of thenbsp;sandy coast of Llanfairfechan in N. Wales, and obtained figures whichnbsp;look exactly like the forms of leaves of recent Florideae, such asnbsp;Wormskioldia sanguinea. This is quite enough to show how little value isnbsp;to be set upon the Halymenitae, Delesseritae, Laminaritae, and Caulerpitaenbsp;of authors, even if there can be no doubt that some of them are real impressions of Algae ; this is proved, for example, in the case of Halymenitesnbsp;Arnaudi ^ by the presence of a Membranipora, which has been preserved atnbsp;one spot in the impression.

Saporta, like Schimper before him, lays special weight on the copious branching shown by many of the algal remains which he defends. Henbsp;denies with Schimper that there can be any branched animal tracks.nbsp;Zeiller � however very recently made known an excellent instance of thisnbsp;very thing. He observed in Normandy on the moist clay bottom of somenbsp;dried-up puddles some curious branched rounded elevations formed simplynbsp;of small raised lumps of clay, and agreeing very nearly in outward appearance with the Jurassic genus Phymatoderma ; these lumps formed the roofnbsp;of a system of passages which had been made by some burrowing animalnbsp;beneath the surface of the ground. The impressions of the claws on thenbsp;inner wall of the passages were evidently those of the common mole-cricket,nbsp;which with its rounded back had lifted up the thin roof of soil and brokennbsp;it up into small pieces. In a similar manner various forms may be explainednbsp;in which the theory of foot-tracks has difficulties to encounter, and this maynbsp;be the case especially with many of the branched forms of Bythotrephis andnbsp;Chondrites. The variety of the tubes formed by worms and other creaturesnbsp;on the bed of the sea must certainly astonish every one who by frequentnbsp;visits has made a close acquaintance with the strand at low water.

Hall � has described a specimen as an Alga under the name of Dictyo-lithes Beckii from the Medina sandstone of the Upper Silurian formation of the Stat� of New York. This is at once recognised to be the cast of a claynbsp;floor in a half-dried state and with the cracks forming polygonal areolas as

hm nbsp;nbsp;nbsp;an overlying layer. The fissures which bound the separate

Out ^ nbsp;nbsp;nbsp;ss reticulately connected ridges in half-relief, from which run

small blind processes, the casts of small capillary fissures.

Co � ^ ^ *-here are a large number of specimens of this class now under , ^^^tion, to which Nathorst�s explanation can only be applied withnbsp;givinbsp;nbsp;nbsp;nbsp;applied at all. Saporta ^ acted judiciously in entirely

� up Cro.ssochorda, while drawing attention at the same time to the whi ^nbsp;nbsp;nbsp;nbsp;indistinctness of his opponent�s preparations in plaster of Paris,

many cases very imperfectly serve the purpose for i-^'acknbsp;nbsp;nbsp;nbsp;were intended. But if the objects in question are not the

th ^ animals, it does not therefore follow, as Saporta maintains, that j-j. ^ Algae. They may for instance be the excrements of many marinenbsp;composed of shaped masses of mud or sand, such as may oftennbsp;in, suitable spots on the sea-shore. In this case the object will ofnbsp;project in half-relief on the upper surface of the beds. The group

also'

alsQ ^

uiks, to regard it as an Alga. That this fossil is no track of an mnbsp;nbsp;nbsp;nbsp;proved at once by the spirally twisted specimen figured by Hall�,

'quot;b several convolutions lie one above the other and do not intersect Is usually the case. It appears also from the text that

Nathor

Arthrophycus-tubes do not project on the under surface of the slab, ^_^borst�s view requires, but on the upper. I gather this from thenbsp;franbsp;nbsp;nbsp;nbsp;Words of the text ^ : � �since great surfaces are crowded with its

jj^c^'^^bts; and these layers are covered only by a deposition of a few when another growth, equally abundant, is found upon the succeed

pla nbsp;nbsp;nbsp;being the state of the case, I am precluded from entering in this

npon a detailed description of the fossil remains belonging to this rgonbsp;nbsp;nbsp;nbsp;^nd must limit myself in the following remarks to a brief

.bUtiob of Schimper�s classification and a notice of the chief repre-Sa nbsp;nbsp;nbsp;forms, adding only a few critical remarks on Nathorst�s and

porta s later publications.

Th T ��'oup of Caulerpiteae contains objects of dissimilar appearance.

The

lites

Confirmed in this belief by a letter of Fuchs on the subject of the hondritae of the Flysch printed in his work hnbsp;^ The group of Alectoruridae, with the genera Alectorurus, Taonurus,nbsp;ancellophycus, Glossophycus, contains a series of remarkable remains fromnbsp;Silurian up to the Tertiary formations; they have been admirablynbsp;_ �Ured in the works which have been already so often cited, and particularlynbsp;Among them is the so-called Cock�s-tail Alga (Spirophytonnbsp;^auda Galli), which occurs in such abundance in certain beds of the Uppernbsp;evonian formation in America, that it has given them the name of � Caudanbsp;^aili grits.� Descriptions and figures of this fossil will be found in L.nbsp;^ciuxem Opinions are much divided on the question whether they arenbsp;organic or inorganic origin. Nathorst considers that he has producednbsp;^tialogous forms artificially; he says on this point; � The experiment ofnbsp;P*'oducing a circular movement in water in a vessel, the bottom of whichnbsp;Covered with fine sand, has supplied me with an excellent imitationnbsp;Spirophyton Cauda Galli; from a small central cavity irregular archednbsp;P^arkings spread on the same side towards the margin, and were not dis-^^'^guishable from the corresponding structure in Spirophyton.� Unfortunately he has given no figure; and since he assumes of other similarnbsp;tnims that they were produced by worms, or by tufts of plants fixed at thenbsp;of the sea and moved about by the wave.s, he gives us the im-P�'ession of not being quite clear in his own ideas on the subject. Thenbsp;t�gure which he gives of an analogous form produced by a worm^ hasnbsp;a very general resemblance to the fossils which we are considering,nbsp;nere are also cases in which these Taonurae do not merely project innbsp;half-relief, but form perfectly separable casts between the' layers, the marginnbsp;being arched over and thickened into a cushion I do not quite see hownbsp;can conceive such a cast to be formed by eddies in water; but I am asnbsp;httle able to discover in these remains the Siphoneae which Saporta seesnbsp;them.

A few words only are required here for the fossil Mosses, which being obtained almost entirely from Tertiary and Quaternary deposits and beingnbsp;^^osely allied to recent forms are of scarcely any interest to the botanistnbsp;tost of those hitherto found are barren ; a single capsule only appears tonbsp;� known, and this has been described by Ludwig� as Gymnostomumnbsp;fctrugineum from the Miocene haematites of Dermbach in Nassau; Schim-Pcr Considers � it to belong to Sphagnum, and calls it Sph. Ludwigii. Thenbsp;deader may be fitly referred to Schimpers work for an account of thenbsp;tolerably numerous barren Hypneae and other remains of Mosses whichnbsp;b^ve been found in a fossil state. The type of Marchantieae is known in

tion, are considered by him to be of doubtful character, and I do not know them from personal inspection. The question whether Chordophyceae,nbsp;Crossochorda, Gyrochorda and also Phyllochorda may be tracks of animalsnbsp;has been already fully considered. Whether the Silurian Bilobites, Dekaynbsp;(Cruziana, d�Orb.) is of the same nature I am unable to determine. Twonbsp;elaborate monographs on these fossils by Saporta ^ and Delgado ^ havenbsp;recently appeared, and these contain also a complete account of the extensive and scattered literature. Both authors are at great pains to provenbsp;that the remains are those of Algae, but they will scarcely induce thenbsp;botanists to take this view; they have equal claims to be regarded asnbsp;Holothuriae, Ctenophorae, sponges or anything else we may please to callnbsp;them. As regards the Arthrophyceae, it has been already shown thatnbsp;Nathorst is wrong in referring the type of this group to the tracks ofnbsp;animals. The Taenidiae� I have never examined ; Nathorst considers thatnbsp;they are the tubes of worms. The Dictyophyteae (Dictyophyton, Uphan-taenia) are referred by Hall ^ to sponges.

The genus Oldhamia � from the Cambrian slates of Ireland, which has been supposed to be the oldest of all vegetative types and appears only asnbsp;i a delicate wrinkling of the surface of hard slate beds, is now regarded bynbsp;F. Romer � and indeed by most observers as the result of simple pressure ornbsp;some similar purely mechanical cause. Saportatoo would seem not tonbsp;consider these markings to be of vegetable origin, or he would not havenbsp;failed to mention them as the oldest types of the class of Algae. Withnbsp;Scolithus, Haldem., Vexillum, Rouault, Eophyton, Torell, and Granularia,nbsp;Sap.�, we come at last to shapeless objects of quite indefinite character.nbsp;Eophyton has been already discussed; Vexillum is produced every day innbsp;the soft mud of our ponds, where local currents are interfered with bynbsp;floating impediments, such as branches of trees and the like,nbsp;v/nbsp;nbsp;nbsp;nbsp;The Chondriteae, which occur in all formations and when found in the

older deposits generally go by the name of Bythotrephis, are remarkable for their copious branching. Innumerable figures of them are given in thenbsp;works of Heer� and Saporta^�. The latter says of them and of countlessnbsp;other forms �In fine, we have no hesitation in referring the whole ofnbsp;this assemblage of primordial types to one of the groups of inferior Algae,nbsp;that of Siphoneae; this group has arisen from a very remarkable differentiation of a thallus, which though branched continues to be unicellular, amp;c.�nbsp;Nothing further need be added to this statement from the botanist�s pointnbsp;of view. Nathorst of course regards them as traces or tubes of worms, and

gt; de Saporta (12). nbsp;nbsp;nbsp;� Delgado (1).nbsp;nbsp;nbsp;nbsp;^ Heer (3), t, 67.nbsp;nbsp;nbsp;nbsp;�* Hall (2).

� Zittel (1), vol. ii, p. 60. nbsp;nbsp;nbsp;quot; F. Romer (1).nbsp;nbsp;nbsp;nbsp;� de Saporta (3).nbsp;nbsp;nbsp;nbsp;� de Saporta

(4), vol. i, t. 12. nbsp;nbsp;nbsp;* Heer (3).nbsp;nbsp;nbsp;nbsp;de Saporta (4), vol. i.nbsp;nbsp;nbsp;nbsp;� de S.aporta (3), p. 93.

several species of the genus Marchantia, which agree in habit with forms now living in the tropics. Two of them have been described by Saporta^nbsp;from the Eocene tuffs of S�zanne, and are mentioned also by Schimper^.nbsp;Jungermannieae have been found in small fragments in amber.

The Muscineae no doubt had their representatives in the times of the older formations also. Still it is very remarkable that so few and uncertainnbsp;traces of the forms then existing have come down to us. Heer� has foundnbsp;himself obliged to appeal to the caterpillar-genus Byrrhus in order to provenbsp;the existence of Mosses at the period of the Lias. As these creatures livenbsp;on Mosses at the present day, he concludes that there must have beennbsp;Mosses at that time also. That the conclusion is open to objection isnbsp;evident. Renault and Zeiller ^ have however quite recently describednbsp;remains from the Coal-measures of Commentry, which look like barrennbsp;Polytrichae or Rhizogoniae, and which they name provisionally Muscitesnbsp;polytrichaceus.

III.

In departing from the customary arrangement in the Natural System placing the Gymnosperms before the Vascular Cryptogams we havenbsp;influenced chiefly by practical considerations, for the adoption of thisnbsp;�rder will facilitate the discussion of the many doubtful forms which belongnbsp;one or other of these classes, but which it will be best to consider innbsp;Connection with similar groups of Archegoniatae.

Remains of Coniferae, branches, leaves, cones and seeds, are found great abundance in the Cainozoic and in the most recent of the Mesozoicnbsp;'�Nations, and have been referred to genera still living on account ofnbsp;cir resemblance to them. Where such determination is based on well-Pieserved cones, it may as a rule be considered satisfactory. Where thenbsp;Cones are not in such good condition, we must keep in sight the possibilitynbsp;confounding them with cones and stems of Cycadeae. Where seedsnbsp;have been preserved, the task is at once more difficult. Leaves andnbsp;branches can be regai'ded by the botanist only in single exceptionalnbsp;Cases'as a safe basis for the determination of genera or groups, for thenbsp;cliaracters which they offer are few and not well marked, and the valuenbsp;cf these few must be regarded as doubtful when we remember that therenbsp;recent genera from different families, in which the leafy branches cannotnbsp;c distinguished at all by the outward appearance and with difficulty evennbsp;y anatomical examination. Diselma Archeri, Hook, and Microcachrysnbsp;Rtragona, Hook, are examples of such forms. How difficult it wasnbsp;shnbsp;nbsp;nbsp;nbsp;male and female specimens in these plants correctly is

nwn by their peculiar synonymy. Nor must the heterophylly be for-�cgt;tten, which prevails so widely in the Coniferae. We have only to think Jciniperus virginiana, of Retinospora in the young states in the Cupres-�'^eae, and of Glyptostrobus chinensis. Voltzia heterophylla, which willnbsp;c Considered below, is an example of the same phenomenon in fossil forms�nbsp;ds name imports. Perfect certainty therefore in the determination ofnbsp;. *^^ches of Coniferae can only be attained when we find them in con-Jciriction with cones in a satisfactory state of preservation. But in manynbsp;c^scs the two are not known in actual connection, being only associated

in the ordinary manner. The younger the formations which contain the separate parts, and the more complete the resemblance to those of thenbsp;recent form which serves as a tertium comparationis, the more shall wenbsp;be justified in drawing the tempting but almost always hazardous conclusion that they belong to one another.

The older formations also contain an abundance of remains of Coni-ferae, but it very rarely happens that their relation to still living forms can be determined with any certainty. The structural details in the conesnbsp;are usually badly preserved; the number and position of the ovules, thenbsp;most important points, are either unknown or very uncertain. Moreover,nbsp;the descriptions of palaeontologists in this respect are often a good dealnbsp;coloured by the imagination. An instance of this is to be found in thenbsp;doubtful Albertia, Sch., which Schimper^ confidently classes with Dam-mara, and Schenk ^ then deals with in a similar manner. Heer � goes sonbsp;far as to say : � The family of Abietineae appears in the Coal-measures innbsp;two genera, Walchia occurring as early as the middle of the formation,nbsp;Ullmannia, as far as is yet known, only in its upper limits.� I shallnbsp;endeavour to show that nothing is known of either genus which can benbsp;turned to account by the botanist, and that Heer�s assertion therefore isnbsp;only calculated to lead those botanists, who have not occupied themselvesnbsp;closely with fossil plants, into errors and false conclusions. And I cannotnbsp;say that I agree even with Schenk when he classes things like Brachy-phyllum, Sphenolepidium, and Inolepis directly with the Taxodieae. Hisnbsp;criticism does not appear to me to go nearly far enough, though in othernbsp;respects it is thoroughly good.

From all this it follows that our present purpose will be best served by dividing the whole mass of described forms into those in which thenbsp;connection with living groups is botanically assured, or is of such a kindnbsp;that only one of these groups can be compared with them, and, secondly,nbsp;into those in which this connection is still doubtful; lastly, we must brieflynbsp;examine the results of investigation into the fossil woods which are sonbsp;common in all the formations. The reader is referred to Schenk�s account^nbsp;for elaborate descriptions of the forms which represent our living genera;nbsp;such descriptions would be unsuitable to this work, in which we are concerned only to show what are the oldest and most certainly establishednbsp;representatives of each of the main forms,* and thus to gain some groundnbsp;for determining their relative age.

The Abietineae are abundant in the Tertiaries and in the Chalk, but they can as a rule be certainly determined only in their cones, or in thenbsp;case of the Pines in the needle-bearing branches, if these are present in

the necessary state of preservation. They are less abundant in the Juiassic system. The oldest remains, which are not however absolutely free fromnbsp;doubt, come from the Rhaetic beds of Schonen. All known Mesozoicnbsp;cones of Abietineae belong, as far as I am aware, to the genera which havenbsp;no squamae apophysatae. The Cenomanian beds are the earliest whichnbsp;Supply forms of the section Pinea of Pinus. A few cones are known from

is not free from doubt, though the figure certainly resembles a small expanded cone of Cedrus. It is possible that this Pinites Lundgreni, Nath.

been rightly interpreted, since winged seeds of Coniferae are associated ^'th it, but these after all may belong to Palissya which occurs in thenbsp;�^rne beds. Saporta^ figures a splendidly preserved cone, which showsnbsp;even the inner structure perfectly, as Pinus Coemansi, Sap. Unfortunatelynbsp;the label which bears the words, � Oolitic formation, with no further indication of locality or position ; from the collection of M. Coemans,� shows,nbsp;riotwithstanding Saporta�s remarks on the point, that it is not certain thatnbsp;die fossil is Jurassic. Cainuthers � has described several recognisable butnbsp;not very well preserved cones of Abietineae from the Wealden under thenbsp;names of Pinites Dunkeri, Carr., P. Mantellii, Carr., and P. patens, Carr.,nbsp;nlso a splendid and indubitable Cedar-cone^, P. Leckenbyi, Carr., fromnbsp;the Neocomian strata of the Isle of Wight, and from the same beds� annbsp;elongated cone like those of Pinus, which he has named Pinites sussexiensis,nbsp;t^arr. pbe carbonised specimens also from the Neocomian or Wealdennbsp;formations of La Louvi�re in Hainault, described by Coemans are innbsp;''ory fine preservation. Of these, Pinites Corneti, Coem. is no doubt anbsp;f-odar-cone; P. Heeri, P. depressa, and P. Toillezi recall Cembra andnbsp;Strobus; P. Andraei appears to stand between Strobus and Taeda.nbsp;Lastly, P. Omalii and P. Briarti look very like cones of Picea or Tsuga.nbsp;Various single cone-scales from the Chalk of Greenland are figured innbsp;fleer'^; two fine cones, Pinites longissima, Vel. and P. Protopicea arenbsp;figured by Velenovsky *. The cones from the Cenomanian beds of Moleteinnbsp;'a Moravia may also be mentioned ; one of these, Pinites Reussii, Cda., anbsp;fragment only, is described by Reuss ��gt;, the other, P. Quenstedti, Heer,nbsp;having a well-preserved surface and resembling cones from the Mexicannbsp;group of Taeda, will be found in Heer r�. A series of cones from thenbsp;English Eocene formations have been figured by Starkie Gardner rr.

� Nathorst (2), p. 63; t. 15, ff- i, 2. nbsp;nbsp;nbsp;quot; de Saporta (4), vol. iii, p. 474 !nbsp;nbsp;nbsp;nbsp;191.nbsp;nbsp;nbsp;nbsp;� tTarrathers (1).

' Carrathers (V. nbsp;nbsp;nbsp;= Carruthers (1).nbsp;nbsp;nbsp;nbsp;� Coemans (1).nbsp;nbsp;nbsp;nbsp;� Heer (5).nbsp;nbsp;nbsp;nbsp;� Velenovsky (1), t. 7,

f. I and f. 4. nbsp;nbsp;nbsp;� Reiiss (1).nbsp;nbsp;nbsp;nbsp;� Heer (7), t. 2.nbsp;nbsp;nbsp;nbsp;� Gardner (1) (1884).

the different formations, but it is in most cases doubtful whether they belong to the Abietineae. It might indeed be maintained that there is nonbsp;real certainty except in the case of Pinus, and in that genus only when thenbsp;needles are connected together in their tufts. This does not appear to benbsp;very frequently the case; still it can be shown that species of Pinus withnbsp;bundles of two, three, and five needles lived in Europe during the Miocenenbsp;period, and that all except Cembra and Pinus canariensis have maintainednbsp;themselves to the present day in America only side by side with the speciesnbsp;with two needles. From this fact and from the diffusion in circumpolarnbsp;regions of the Arvae, which seem to belong to older types of Abietineae,nbsp;is derived, as we know, the argument for the high antiquity of these membersnbsp;of the American flora, and of that flora generally. Among examples ofnbsp;well-ascertained species with five needles may be cited Pinites Palaeo-strobus, Ett.,^ P. echinostrobus, P. fallax, P. Pseudotaeda, P. deflexa ^; ofnbsp;species with three needles, Pinites Saturni, Ung.�, P. resurgens. Sap., P.nbsp;trichophylla. Sap., P. divaricata. Sap.'*', all of the Tertiary epoch. It is morenbsp;or less probable that many other species were of similar character.

The flat needles resembling those of the Silver Fir, which are frequently recorded by authors from the Jurassic system upwards, and sometimes formnbsp;of themselves entire beds of coal (Abietites Linkii, Dk., from the Wealdennbsp;of Duingen, A. Crameri, Heer, from the beds of Kome in the Urgoniannbsp;formation of Greenland), may be properly passed over for the reasons mentioned above. It may be left to those who are working at the geographynbsp;of plants to put things in order here, which will not be done withoutnbsp;exact and systematic comparative examination of the epidermis of the leafnbsp;in living and fossil forms. Schenk� has made this examination in the casenbsp;of the two species of Abietites just mentioned, and the result is that neithernbsp;of them can belong to Abietineae. Abietites Linkii, Dk. shows on thenbsp;under side of the leaf several rows of stomata-bands separated by broadnbsp;intervals and not lying on the two sides of a median nerve, somewhat as innbsp;Podocarpus. A. Crameri has the stomata in the middle zone of the leaf,nbsp;Heer�s median nerve, and none on the lateral parts of the leaf. In thisnbsp;peculiarity and in the form of the epidermal cells the plant agrees exactlynbsp;with Sciadopitys, and Schenk therefore makes it the representative ofnbsp;Sciadopitys in the period of the Chalk.

A much greater amount of differentiation is presented by the great series of Araucarieae, in which must be included the Sequoieae and Taxo-dieae, if we accept the interpretation of the structure of the flower givennbsp;by Sachs and Eichler. The large generic groups with their marked differences of habit must be discussed one by one.

1 von EtUngshausen (1) (Haring, t. 6, ff. 22-33), and de Saporta (7), t. 3, f. i; t. 4, f. 3-de Saporta (8), t. 3. nbsp;nbsp;nbsp;^ Unger (1), tt. 4, 5.nbsp;nbsp;nbsp;nbsp;� de Saporta (8), t. 4. s 2ittel (1), p. 293.

Jurassic strata, and care is requisite in dealing with it where we have oken cones only before us, that it may not be confounded with stems ofnbsp;eae. The foliage, which varies much, as we know, in recent forms, cannbsp;Con ^nbsp;nbsp;nbsp;nbsp;determined when it is found in actual connection with the

Car^^i nbsp;nbsp;nbsp;general habit is seen in the cone of Araucaria sphaerocarpa,

tjj' nbsp;nbsp;nbsp;Great Oolite of Stonesfield ; the original specimen preseiwed

Geological Department of the British Museum shows the single seed fhe ^^clian position on a detached scale. Of A. Brodiaei, Carr.^, fromnbsp;atrnbsp;nbsp;nbsp;nbsp;(Lower Oolite), we have also a reliable broken cone, which is

shi*^quot;^ P^gc 78. Of A. Philippsi, Carr.�, from the Lower Oolite of York-th nbsp;nbsp;nbsp;characteristic scales are preserved, each scale having one seed,

^ Upper Oolite (Kimmeridge of Bellay) are found leafy cone-bearing denbsp;nbsp;nbsp;nbsp;those of the recent A. Bidwillii, which have been figured and

by Saporta as Araucaria microphylla, Sap.'*^ The same author described cone-scales of A. Moreauana, Sap.� from the Corallinenbsp;Qj- ^ St. Mihiel. Many trustworthy cone-scales also with the impressionnbsp;seeds have been obtained by O. Feistmantel from the Gondwana bedsnbsp;East Indies (which may be Jurassic). The figures of Araucaritesnbsp;Arnbsp;nbsp;nbsp;nbsp;G. Feistm.�, and of A. cutchensis, O. Feistm.�, may be compared.

Only nbsp;nbsp;nbsp;Araucarias described by Gardner� are founded on leafy branches

to Q *�kar branches from the Tertiaries and the Chalk have been referred thenbsp;nbsp;nbsp;nbsp;Hardly any fossil remains of Dammara are known;

�^Hotheleaf-structure of Sciadopitys, as has been already said, descrihnbsp;nbsp;nbsp;nbsp;needle from the Jurassic beds of Spitzbergen has been

Heer and named by him Pinus Nordenski�ldi, but Schmal-Places it' nbsp;nbsp;nbsp;similar leafy branches before him, calls it Cyclopitys and

Saporta*^f4;^^' ^ Carruthers (2). nbsp;nbsp;nbsp;^ Camithers (2).nbsp;nbsp;nbsp;nbsp;* de Saporta (4), vol. iii, t. 186.

P^' iii, p_ 185. � nbsp;nbsp;nbsp;''hnbsp;nbsp;nbsp;nbsp;^84.nbsp;nbsp;nbsp;nbsp;quot; Palaeontologia Indica, ser. II, Gondwana syst. vol. i,

* Zittel (1^ nbsp;nbsp;nbsp;�� t�al. Ind., ser. II, vol. i, pt. i, p. 96 ; t. 14.nbsp;nbsp;nbsp;nbsp;� Gardner (1) (i884\

Zittel (1' frser (3). n Sternberg, Graf von (1). Velenovsky (1). Schmalhausen (1).

work to enter nrore closely into their consideration. Thirdly and last y, Sequoia Sternbergii, Heer, a species resembling S- gigantea in foliation, annbsp;one of the best known and commonest forms, especially in Miocene times;nbsp;but its connection with the Sequoias has been recently questionenbsp;Marion 1 sees in it the type of a peculiar genus known as Doliostrobusnbsp;(D. Sternbergii), and Renault^ assents to his view. Respecting the Englishnbsp;plant known as Cryptomeria Sternbergii, Gardn.�,and identi �nbsp;nbsp;nbsp;nbsp;^

at least of the remains which are associated by authors with the Sequoias, I do not venture to express an opinion. It comes from the asa ic onbsp;�nation� of Ireland ; its cones are plentiful but never found attached to menbsp;branches. These cones, as well as the one figured by Heer , do no mnbsp;fact look excessively like those of Sequoia.nbsp;nbsp;nbsp;nbsp;_

Velenovsky�s new genus Ceratostrobus, with two species, C. sequoiae-Pbyllus and C. echinatus, is closely allied, according to that author , wit Sequoia, standing between it and Cryptomeria. The scales of the smallnbsp;spherical cones in this genus have a long thorn-like process m the middlenbsp;the apical areola. In both species cones and branches ave een ounnbsp;attached to one another; the habit of the latter is to some extent that ot

Spn.,~:

equoia

Oli!r^�^^' widely diffused through the Tertiary formations from the cone^^^*^^ 'upwards; the detached branchlets and the very characteristicnbsp;both found, and are so like those of the living species that mostnbsp;qj. .j, ^ unwilling to separate the fossil form from it, and therefore speaknbsp;th ^^�bluni distichum miocenum. According to Heer� the leafy branches,nbsp;� msembling those of Sequoia Langsdorffii, are however distinguishednbsp;of Tnbsp;nbsp;nbsp;nbsp;having the decurrent leaf-cushions of Sequoia. Good figures

goce nbsp;nbsp;nbsp;Glyptostrobus is abundant also in the Tertiaries from the Oli-

con nbsp;nbsp;nbsp;Heer, besides two less certain forms. The highly characteristic

I'gonian beds of Rome in Greenland, which though somewhat Obscure and not in �^ ---------- ^ . nbsp;nbsp;nbsp;...

non (1). nbsp;nbsp;nbsp;2 Renault (2).nbsp;nbsp;nbsp;nbsp;Gardner (1) (1884), p. 85, t. 10.

blance to recent coniferous forms is only in the habit. The branch bears whorls of many leaves at considerable intervals ; there is no trace of thenbsp;scale-leaves crowded as in a bud, in the axils of which the double needlesnbsp;are placed in the recent plant. Examination of the epidermis of the leaf innbsp;the original specimen might perhaps give some means of judging how farnbsp;this is owing to the bad state of preservation.

The type of the Sequoias is represented by a great number of remains from the younger formations, and these we have been accustomed to considernbsp;chiefly on Heer�s authority ^ as different species of the genus Sequoia. Conesnbsp;are abundant, and are sometimes attached to their branches. It is true thatnbsp;we are acquainted only with the outward appearance of these objects, andnbsp;doubts have recently arisen whether it would not be advisable to unite somenbsp;of them with other nearly allied genera, such as Arthrotaxis^. The foliation connects the fossil forms quite naturally with the recent species of thenbsp;genus, with Sequoia sempervirens and S. gigantea. They extend from thenbsp;Pliocene formations, where they are widely diffused, to the Lower Chalk.nbsp;The most important species found in the Tertiaries, from the Eocene upwards, are the following ; first, Sequoia Couttsiae, showing a foliation whichnbsp;answers to that of our S. gigantea ; cones ai'e figured by Saporta Schenknbsp;and Heer�. But this very form is removed by Gardner to Arthrotaxis,nbsp;and is moreover divided into several species The specimens from Boveynbsp;Tracy figured by Heer�^ are said by Gardner to be lost, and their identitynbsp;therefore with those examined by the latter cannot be ascertained, but thosenbsp;from Hempsted are identical. Gardner adds: � I think it highly probablenbsp;however that the species may be found not to be a true Sequoia, and thenbsp;danger is very apparent of giving the reins to the imagination and picturingnbsp;the slopes round the ancient Bovey water as clothed with woods composednbsp;� mainly� of a huge coniferous tree, whose figure resembled in all probabilitynbsp;the Sequoia gigantea of California � and the warning in existing circumstances is not out of place. Secondly, Sequoia Langsdorffii, Brongn.nbsp;figured by Schimper�; Heer� gives the only representation known to menbsp;of the cone-bearing branch, which is moreover by no means above suspicion. This species comes near the recent Secpioia sempervirens. Formsnbsp;of both kinds appear to have existed as early as the time of the Chalk,nbsp;namely S. Reichenbachii, Heer S. fastigiata, Stbgi\ S. crispa, Vel.^^ belonging to the type of S. gigantea, and S. Smithiana, Heer to the type ofnbsp;S. sempervirens; and these different main forms have a number of othernbsp;forms grouped round them, but it would be foreign to the objects of this

' Heer (5). nbsp;nbsp;nbsp;� Gardner (1) (1884).nbsp;nbsp;nbsp;nbsp;* de Saporta (8), p. 49 ; t. 2, f. 2.nbsp;nbsp;nbsp;nbsp;* Zittel (1)�

p. 297. nbsp;nbsp;nbsp;Heer (9), t. 59.nbsp;nbsp;nbsp;nbsp;' Gardner (1) (1883), p. 38 ; (1884}, p. 90.nbsp;nbsp;nbsp;nbsp;� Heer fi')- j

* Schimper (1). nbsp;nbsp;nbsp;� Heer (11), toI. iii, t. 146, f. i6.nbsp;nbsp;nbsp;nbsp;Heer (7), t. i, � Velenovsky (})gt; i

tt. 8, 10. nbsp;nbsp;nbsp;Velenovsky (1), t. 10.nbsp;nbsp;nbsp;nbsp;Heer (5).nbsp;nbsp;nbsp;nbsp;|

A detailed description of the fossil remains from the group of Cupres-sineae, which are very common in the Tertiary formations, has been given by Schenk The determination of the genera so far as this is based onlynbsp;on leafy branches, though the result of closest comparison, is neverthelessnbsp;an uncertain affair, owing to the near affinity of the forms and the frequentnbsp;change in the foliation of different parts of the same plant. It is otherwisenbsp;where cones are to be had, for genera founded on these may be considerednbsp;to be sufficiently attested. The fossil remains of this group are of so littlenbsp;interest to the botanist that a short notice of them will suffice; nor have I,nbsp;like Schenk, the advantage of an extensive comparative study of the foliationnbsp;of recent forms, and am not in a position therefore adequately to criticisenbsp;his statements. Phyllostrobus Lorteti, Sap.^, from the Kimmeridge of Or-bagnoux, should be the oldest cone-bearing form which certainly belongsnbsp;to this group. A small branch with four regular rows of leaves of dissimilarnbsp;form in the usual decussation bears a cone formed of two pairs of scales andnbsp;resembling the cone of Callitris or Libocedrus, but only moderately well-preserved. The scales of the upper pair are larger than those of the lower.nbsp;Then we are acquainted with fossil cones, undoubtedly of the genus Wid-dringtonia and in excellent preservation, belonging to the Miocene speciesnbsp;Widdringtonia helvetica, Heer�, W. antiqua, Sap.^ and W. brachyphylla,nbsp;Sap.�, also from the Tertiaries, and cones badly preserved indeed but stillnbsp;probably rightly named of W. microcarpa, Sap.� from the Kimmeridge ofnbsp;Armaille. Well-preserved cone-bearing remains of the genus Callitris arenbsp;also known from the Tertiary strata in the South of Fi'ance, and will benbsp;found figured in Saportah Starkie Gardner� very properly classes withnbsp;these some small cones from the London Clay of the Isle of Sheppey, whichnbsp;have been described as Callitris curta and C. Ettingshauseni. The formernbsp;species had been already noticed by Bowerbank� under the name of Cu-pressinites curtus. A single cone with three decussate pairs of scales isnbsp;referred by Saporta to Thuiopsis. A cone-fragment with large unwingednbsp;seeds from the Miocene of Greenland, named by Heer Biota borealis isnbsp;perhaps rightly placed.

While it appears from the above account that the Jurassic system supplies extremely few satisfactory cones of Cupressineae, it contains nevertheless a great abundance of leafy branches, which from the decussatenbsp;arrangement and characteristic position of the leaves may be placed innbsp;this group, as we learn from a glance at the numerous species of Palaeo-cyparis figured by Saporta Among the branches also of Coniferae from

' Zittel (1). nbsp;nbsp;nbsp;^ de Saporta (4), vol. iii, t. 221.nbsp;nbsp;nbsp;nbsp;� Heer (11).nbsp;nbsp;nbsp;nbsp;^ de Saporta (6), t. 3, f. 3-

� de Saporta (5), t. 2, f. 6. nbsp;nbsp;nbsp;quot; de Saporta (4), vol. iii, t. 219.nbsp;nbsp;nbsp;nbsp;'' de Saporta (6), t. 3, f. 2 !

(7) , t. I, f. 3 ; (8), t. I, f. 6.nbsp;nbsp;nbsp;nbsp;� Gardner (1) (1883), t. 9.nbsp;nbsp;nbsp;nbsp;^ Bowerbank (1).nbsp;nbsp;nbsp;nbsp;� de Saporta

(8) , t. I, f. 5.nbsp;nbsp;nbsp;nbsp;� Zittel (1), p. 322.nbsp;nbsp;nbsp;nbsp;de Saporta (4), vol. iii.

man ^ '''Vhich were all called Artlirotaxites or Echinostrobus princeps, thenbsp;nbsp;nbsp;nbsp;of Palaeocyparis may be distinguished by the position of

justifieddetermine from branches alone, we should be (jg ? classing with Cupressineae the peculiar remains which were firstnbsp;j)�inbsp;nbsp;nbsp;nbsp;fern-leaves under the name of Moriconia Cyclotoxon by

^cuquot; th^ nbsp;nbsp;nbsp;origin. This form shows the pinnate habit of the fern-leaf,

Cun nbsp;nbsp;nbsp;disposed in alternating rows, exactly after the manner of the

of these fossils are to be found in Zittel^ and Heer^. Schenk known at present only from the Chalk, and is compared bynbsp;^ulated k-*docedrus. To the Chalk also belong certain distinctly arti-rows^ ^^^uch-systems with lateral branches pinnately disposed in twonbsp;internf*�-ks of decussated slightly projecting scales separated by longnbsp;itegnbsp;nbsp;nbsp;nbsp;often not preserved ; these fossils, formerly known as Culm-

j-g^l�l been named by Schenk � Frenelopsis Hoheneggeri. That they Qfnbsp;nbsp;nbsp;nbsp;fke Cupressineae has been made probable by the researches

keds f^^ � examined the epidermis in specimens from the Turonian ^hicl^nbsp;nbsp;nbsp;nbsp;und found that the stomata showed certain peculiarities

Suished^^'quot;'^**' k'renela; but Schenk �� points out that they are distin-leaf-^jj nbsp;nbsp;nbsp;Frenela by having two members only and not three in the

kurias^ �Peaking of the Taxineae it will be convenient to leave the Salis-^onsirl' ^ special group, for after consideration. They may be properly ggj.j^nbsp;nbsp;nbsp;nbsp;g*�oup apart on account of the peculiar development of the

�f we do not with van Tieghem and his school explain the shoot as a fertile scale bearing several ovules. Of thenbsp;liaritie fu^'ms, the majority of which have only slightly marked pecu-fossil tnbsp;nbsp;nbsp;nbsp;vegetative organs, few remains have been preseiwed in the

�doubtful nbsp;nbsp;nbsp;affinities of these are in most cases more than usually

lotajjus nbsp;nbsp;nbsp;plainly expressed in Schenk�s * account of Torreya, Cepha-

the hab^^'^^^'^ Cephalotaxites insignis, really belongs to the Taxineae, Part of thnbsp;nbsp;nbsp;nbsp;1� show, we should have this type from the uppermost

forrueri ^ kalk. Remains of leaves from the Rhaetic beds which were Uowcrei^ considered to be the ultimate ramifications of Phyllocladus, arenbsp;fa era y regarded as pinnae of a Fern or Cycad (Thinnfeldia). Heer�^

-- V-,- nbsp;nbsp;nbsp;' de Saporta (9).nbsp;nbsp;nbsp;nbsp;� Zittel (1), p. 318.nbsp;nbsp;nbsp;nbsp;* Heer (5).

also Zittel (1), p. 314. c Zeiller (2). nbsp;nbsp;nbsp;� Zittel (1), p. 314-nbsp;nbsp;nbsp;nbsp;' Zittel (1).

'f' *� f3' nbsp;nbsp;nbsp;F. Braun (1).nbsp;nbsp;nbsp;nbsp;u i-jeer (5), vol. 3 ii, p. 129; t. 17.

has recently made us acquainted with a phylloclade bearing seeds from the Upper Chalk of Spitzbergen, which he names Phyllocladus rotundifolius,nbsp;Heer. Without a knowledge of the original specimen it is impossible to saynbsp;whether this determination can be justified or not. Lastly, Schenk ^ hasnbsp;suggested a comparison of his Conchophyllum Richthofeni from the Coal-measures of China with the female spikes of Dacrydium, though he is notnbsp;prepared to place it with Dacrydium ; for the present this fossil also mustnbsp;remain quite doubtful.

Bertrand^ has described some carbonised shells of seeds found in local deposits filling pockets in the Cenomanian limestones above the Wealdennbsp;formation of Tournay in Belgium, whieh from their structure he places between Cephalotaxus and Torreya, and names Vesquia Tournaisii. He showsnbsp;that these two genera are the only living forms of Taxineae in which twonbsp;vascular bundles traverse the integument or shell of the seed, and that theynbsp;are distinguished from one another by the distance which the two bundles,nbsp;which occupy the margins of the seed, run in the woody layer of the seed-coat. Vesquia shows a similar structure; the bundles are destroyed, and innbsp;their places a canal runs throughout the whole length of the hard seed-coat;nbsp;but there is still the possibility that the seeds in question may have belongednbsp;to one of the many Salisburieae of that epoch, Baiera, or Phoenicopsis, ornbsp;Feildenia. If Ginkgo itself has no vascular bundles in its integument�, thisnbsp;is no proof, as the comparison of Taxus with Torreya shows, that there couldnbsp;have been no bundle in those older allied forms.

Ginkgo biloba, the single living type of the Salisburias, stands, as we know, alone, a perfect stranger, in the midst of recent vegetable forms. Thenbsp;tree, unknown in the wild state and preserved only in the groves of Chinesenbsp;temples, seems to have been kept from extinction by the care of the priests.nbsp;But it is almost certain that it is really the survivor of a series of alliednbsp;plants which was rich in species and individuals. The merit of supplyingnbsp;proof of this belongs to Heer^. It is true that some of these forms werenbsp;already known, having been found in different formations from the Rhaeticnbsp;beds upwards, but they had been taken for Ferns and had been generallynbsp;described as Cyclopteris and Baiera. Of these forms Heer at first selectednbsp;two especially, which are figured in Brongniart � as Cyclopteris digitata, andnbsp;in Lindley and Hutton � under the same name. Heer distinguished these asnbsp;Ginkgo digitata. Heer, and G. Huttoni, Heer, on the strength of his materialnbsp;from the Lower Oolite of Spitzbergen in which he recognised them, andnbsp;added some other species to them. That these leaves were not the pinnatenbsp;leaves of ferns he concluded from their long stalk, on which the lamina

gt; Schenk (2), t. 42. nbsp;nbsp;nbsp;^ Bertrand (1).nbsp;nbsp;nbsp;nbsp;� C. E. Bertrand, �tudes sur les teguments s�minaux

des v�g�taux phan�rogames gymnospermes, in Ann. d. Sc. Nat., s�r. 6, vol. vii (1878), p. 70-* Heer (1) and (5). nbsp;nbsp;nbsp;� Brongniart (1), vol. i, t. 61, ff. 2, 3.nbsp;nbsp;nbsp;nbsp;' Lindley and Hutton (1), vol. i, t. 64.

^ basal swelling above the smooth plane of separation. Cfinkoquot;^Knbsp;nbsp;nbsp;nbsp;confirmed in the happy idea of comparing them with

'quot;oundi.l S^^ris, together with short bits of branches thickly beset with jjjj ' scars which he compared to the short shoots of Ginkgo. It wasnbsp;leavesnbsp;nbsp;nbsp;nbsp;similar objects were found associated with Ginkgo-like

Qf other localities also in the polar zone, and with the further addition trith ^�^ors also resembling those of Ginkgo. Frorn all this we maynbsp;ferns tl^^^ ^o�^sider it as proved that these leaves cannot be the leaves ofnbsp;the 'nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;'^lew of them it is true rests chiefly on a conclusion from

leaves, seeds and branches, which does not give ij. jg . ^ oeitainty, though it appears to be better founded in this case thannbsp;his fnbsp;nbsp;nbsp;nbsp;other in the older formations. Heer ^ says that the nervmtion in

gp nbsp;nbsp;nbsp;there the nerves which are of equal strength simply diverge and

lobes ^long the lower leaf-margins and send branches into -the leaf's so ' 1 nbsp;nbsp;nbsp;states that Baiera pluripartita, Schimp, from the Wealden

Sonus b^^ ^ allied to his Ginkgo digitata that it must be placed in the same preserv ^ ^nbsp;nbsp;nbsp;nbsp;oertain of this, because, after examination of the best-

tbg nbsp;nbsp;nbsp;�Pocimens of the form from Osterwald in the Deister country in

'''hat nbsp;nbsp;nbsp;collection, I have satisfied myself that the nervation is some-

^^0 best nbsp;nbsp;nbsp;from that of Ginkgo. It is however very different even with

quot;orves ^^^^''al at one�s disposal to get a clear view of the course of the 'nters 'nbsp;nbsp;nbsp;nbsp;close to the stem, which is the chief point, because the

of nbsp;nbsp;nbsp;between them are here very small and the thickness of the strip

'''hich � nbsp;nbsp;nbsp;determination. In the same work, and in the next section,

the view nbsp;nbsp;nbsp;Jurassic flora of Eastern Siberia, Heer on the strength of

1-u the o- g^'ued has gone a good deal further by adding several species genera^^^^'^^nbsp;nbsp;nbsp;nbsp;conceives it, and associating with it a number of

that�T^ P^iticularly Baiera, F. Braun, in an amended form. His work die Ch^ IVnbsp;nbsp;nbsp;nbsp;should be consulted for further species of Ginkgo from

Ivliocen^ Greenland and from Eocene and Miocene strata. One of the the livino-�*^^�-*^' ^'^'^quot;toides, Heer, found at Sinigaglia is closely allied tonbsp;''stnoved^ �Pucies. Heer illustrates the genus Baiera, from which he hadnbsp;'-hiefly fj.nbsp;nbsp;nbsp;nbsp;the older species in order to put them under Ginkgo,

Oolite of Siberia, and according to Saporta^ in the Coralline Oolite of France. Better-known species of the genus are Baiera Miinsteriana, Heer,nbsp;from the Rhaetic beds of Bayreuth, and B. paucipartita, Nath., from thenbsp;same formation at Schonen. The Chalk also has produced remains ofnbsp;Baiera, which may to some extent be accepted. The leaves of Baiera,nbsp;which are repeatedly and dichotomously inciso-partite, are distinguishednbsp;from those of Ginkgo by the shortness of the leaf-stalk and by the narrownbsp;ribbon-like form of the greatly elongated leaf-lobes, in which according tonbsp;Heer there is no further bifurcation of the nerves. In the specimen ofnbsp;B. paucipartita, Nath., figured in Schenk^, the leaves which are only slightlynbsp;divided are seen to be collected together, as in Ginkgo, at the summit of anbsp;branchlet. Later investigations leave little room for doubt that Salisburieaenbsp;are to be found as early as in the Permian formation, and Saporta � maintains that we have the genus Ginkgo itself in his Salisburia primigenia fromnbsp;the Permian deposits of Russia. The habit is not against this conclusion,nbsp;but I will not venture to decide. The species Baiera digitata, Heer,nbsp;peculiar to the Kupferschiefer of Europe, was formerly regarded bynbsp;most writers as an Alga'*' (Fucoides Zonarites); it is found usuallynbsp;in somewhat doubtful fragments, seldom in a perfect state, and appearsnbsp;always to have had leaves with only few incisions ; in the American Baieranbsp;virginica, Font, et White�, the leaf-division was more copious. Thesenbsp;authors � also describe a type of leaf from the same formation in Pennsylvania as Saportaea salisburioides, Font, et White, in every respect like thatnbsp;of Ginkgo, and with a nervation which is even essentially the same as in ournbsp;own recent species. The genus Rhipidopsis, Schmalh. also may accordingnbsp;to Schmalhausen�s description be very near to Ginkgo; the leaves withnbsp;their deep flabelliform incisions show similar nervation and symmetricalnbsp;configuration, the broadly wedge-shaped sections being very large in thenbsp;middle of the leaf and diminishing very rapidly toward the side, so thatnbsp;they appear at last quite diminutive and rudimentary.

It was stated above that the leaves of Ginkgo and Baiera of the Lower Oolite of Eastern Asia are associated with fragments of branches, remainsnbsp;of seeds, and male flowers. The branches and seeds are considered bynbsp;Heer* to belong to Ginkgo digitata and also to Baiera Czekanowskiana �;nbsp;some male flowers and the stalk of a female inflorescence are assigned bynbsp;him to Ginkgo Huttoni, other male blossoms to G. sibirica. The flowersnbsp;are really like those of our own plants, but they are perhaps stouter, andnbsp;have longer filaments standing out stiffly from the axis and bearing at theirnbsp;apex two or three spreading pollen-sacs. Heer�s remarks on this point

� de Saporta (4). nbsp;nbsp;nbsp;* Zittel (1), p. 262.nbsp;nbsp;nbsp;nbsp;� de Saporta (2), p. 145.nbsp;nbsp;nbsp;nbsp;* Brongniart (1), t. 1, f. 9-

� Fontaine and White (1). nbsp;nbsp;nbsp;' Fontaine and White (1), p. 102 ; t. 38.nbsp;nbsp;nbsp;nbsp;�� Schmalhaiisen (!)�

* Ileer (.5), vol. 4 i, t. JO. nbsp;nbsp;nbsp;� Heer (.5), vol. 4IJ, t. 10.nbsp;nbsp;nbsp;nbsp;Heer (1), p, 3.

once f ^�^�nlted. With Baiera longifolia and B. Czekanowskiana Heer number^'^'^nbsp;nbsp;nbsp;nbsp;differing from those of the Ginkgo-forms in the larger

is g nbsp;nbsp;nbsp;nmbellately arranged pollen-sacs. Their connection with Ginkgo

beds of^B^ Schenk�s^ discovery of quite similar flowers in the Rhaetic him ^oiberg in company with Baiera longifolia, which are described bynbsp;these fl ^�quot;Oyopitys Preslii and are figured by Schimper''*. In some ofnbsp;'�heynbsp;nbsp;nbsp;nbsp;pollen-sacs spread like the spokes of a wheel, in others

Sohenk down, being attached above to the common conical connective; able thnbsp;nbsp;nbsp;nbsp;'hat this indicates a generic difference, but it is conceiv-

Unfold� d^^ nbsp;nbsp;nbsp;'he condition of the anther before, the former after it

^uch 'hrmation of Siberia with the Salisburieae, but their position is Tj^jg .nbsp;nbsp;nbsp;nbsp;^ eertain than that of the forms which we have just been considering.

Cggj^a nbsp;nbsp;nbsp;tonbsp;nbsp;nbsp;nbsp;the circumstance that Heerquot;* was tempted to compare

ren '^�''^�hia with Isoetes. Czekanowskia has fascicles of linear leaves wheth ^nbsp;nbsp;nbsp;nbsp;dichotomously branched and with capillary terminal lobes ;

They '�'hey have one or several nerves is not clear from Heer�s description. �dtish^\^'^'^�nbsp;nbsp;nbsp;nbsp;^nbsp;nbsp;nbsp;nbsp;have satisfied myself from original specimens in the

crowded nbsp;nbsp;nbsp;several together on a short slender shoot beset with closely

dichot ^�'^'^�'caves ; and it is this shoot which in conjunction with the �ystenbsp;nbsp;nbsp;nbsp;division of the leaves has turned the scale in determining the

of U., nbsp;nbsp;nbsp;is evident from the constant occurrence of connected fascicles

Or g � r ne leaves are often beset with ovoid swellings arranged in rows Wouldnbsp;nbsp;nbsp;nbsp;crowded together and of doubtful character, which Heer

Heers '� leaf-fungi. If the very peculiar fructification figured by 'his pnbsp;nbsp;nbsp;nbsp;belongs to Czekanowskia, as almost seems to be the case, still

^ubit ^'^'^^^PP^urs to me to be essentially distinct from Ginkgo, and the als c rightly judges, reminds us rather of Ephedra. Similar fossilsnbsp;� gured by Schmalhausen �.

leaves nbsp;nbsp;nbsp;surrounded by small scale-leaves, and fall off entire ; but

^urrowino- Suite simple undivided and ribbon-like, rounded at the apex, ^cer gradually to the point of attachment, and sessile. According tonbsp;�^Ust be^^nbsp;nbsp;nbsp;nbsp;simple parallel nerves. In connection with Phoenicopsis

(.3), t. 6. nbsp;nbsp;nbsp;2 Schimper (1), t. 75, ff. 15, 16.nbsp;nbsp;nbsp;nbsp;* Zittel (1), p. 261.nbsp;nbsp;nbsp;nbsp;^

4 n, p. nbsp;nbsp;nbsp;5nbsp;nbsp;nbsp;nbsp;^g_ 6 Schmalhausen (1).nbsp;nbsp;nbsp;nbsp;Heer ( ),

^ �gt; t 3D. nbsp;nbsp;nbsp;8 Hpav /-k\nbsp;nbsp;nbsp;nbsp;---- . ^ nbsp;nbsp;nbsp;-

fossil from the Miocene beds of Spitzbergen and Grinnell-land. The leaves are essentially like those of Phoenicopsis; they have scars at their base atnbsp;the point of separation, and several nerves. They do not however grow onnbsp;short shoots, but are found attached in spiral arrangement to a piece of anbsp;branch. Hence since the resemblance to Phoenicopsis is in the ribbon-likenbsp;leaves only, and the two forms belong to so widely separated formations, itnbsp;seems to me a somewhat violent proceeding to unite them; the comparisonnbsp;with section Nageia of Podocarpus suggested by Heer is more promising.nbsp;Schenk ^ has described under the name of Eolirion primigenium a branchnbsp;from the lowest beds of the Chalk of Wernsdorf in the Carpathians, whichnbsp;is closely beset with large ribbon-like leaves. He has since referred it tonbsp;Phoenicopsis from which it is essentially distinguished by having no shortnbsp;shoots. It seems to me that in Eolirion and Eeildenia we have before usnbsp;representatives of forms which we cannot yet determine from want ofnbsp;material. We must wait for future fortunate discoveries, especially in thenbsp;Chalk.

Other genera, usually referred by authors to this group on what seem to me to be somewhat doubtful grounds, are Ginkgophyllum, Sap. Whit-tleseya, Lesq., Trichopitys, Sap., Dicranophyllum, Grand� Eury. In Ginkgophyllum, the type of which is G. Grasseti, Sap. from the Permian beds ofnbsp;Lod�ve figured by Schenk somewhat irregularly incised leaves like thosenbsp;of Ginkgo or Baiera are attached to an elongated branch, on which theirnbsp;insertions run a long way down. There is no indication that the stalk wasnbsp;channelled, nor is there any evident point of separation. Saporta ^ reckonsnbsp;among species of this genus a lobed leaf-fragment from the Permian of thenbsp;Ural, Ginkgophyllum Kamenskianum, Sap., and also a form from thenbsp;English Coal-measures, G. flabellatum. Sap. (Psygmophyllum, Schpr),nbsp;which is figured in Lindley and Hutton� as a species of Noggerathia.nbsp;Some single short-stalked leaflets ending above in an obtuse toothed marginnbsp;have been described by Lesquereux � under the name of Whittleseya, andnbsp;are figured also in Renault but they are for the present of no value to thenbsp;botanist. The type of Trichopitys is also a fossil from the Permian beds ofnbsp;Lod�ve, T. heteromorpha, figured by Saporta ^ This is a branch withnbsp;elongated internodes, and leaves which split up by repeated dichotomy intonbsp;fascicles of fine linear divergent lobes. At the base of a lateral branchnbsp;which has been preserved the leaves are abbreviated and little or not at allnbsp;divided. In the axils of the leaves are seen here and there stalked bud-likenbsp;forms, which Saporta ^ has since sought to explain as ovules. I saw in Parisnbsp;at the Ecole des Mines a specimen agreeing with Saporta�s figure. The

' Schenk (4). nbsp;nbsp;nbsp;* Zittel (1).nbsp;nbsp;nbsp;nbsp;� Zittel (1), p. 260.nbsp;nbsp;nbsp;nbsp;* de Saporta (2), pp. 144 and gi-

5 Lindley and Hutton (1), vol. i, tt. 28, 29. nbsp;nbsp;nbsp;� Lesquereux (1).nbsp;nbsp;nbsp;nbsp;� Renault (2), vol. vf'

t. 5, ff. 9, 10. nbsp;nbsp;nbsp;� de Saporta (4), vol. iii, t. 152.nbsp;nbsp;nbsp;nbsp;� de Saporta (2), p. 92.

e remains from the Coal-measures, which are at present styled after Grand� Eury ^ and are still little understood, can likenbsp;Iheirnbsp;nbsp;nbsp;nbsp;genera be compared with Salisburieae only on the strength of

�urcated leaves. They must be briefly noticed here on account of gg '�'d^nection, though they should properly have been referred to the lastnbsp;innbsp;nbsp;nbsp;nbsp;Coniferae. The Dicranophyllae, figures of which are to be found

Do nbsp;nbsp;nbsp;and Zeiller� as well as in Grand� Eury, are represented by

nod nbsp;nbsp;nbsp;thick branches with spirally arranged leaves and short inter-

c � ^quot;dd with their surface marked out into rhombic areolae closely �'d together and raised in the centre, like those of Lepidodendrae,nbsp;�nch giving rise to a leaf. The leaves are narrow needles, repeatedlynbsp;dichotomously branched, and on the older branches are usually stronglynbsp;tgj-gnbsp;nbsp;nbsp;nbsp;^ have been able to satisfy myself with respect to these charac-

rs by personal examination of many fine specimens at the �cole des Mines �dt Paris.

i'hn genera still to be considered some are probably connected with the series of Araucarieae, though we cannot say exactly to which ofnbsp;. �'^rit types in that series they belong; the systematic position of thenbsp;IS quite unknown. We must hope that further discoveries will enablenbsp;�d� to explain them.

^ nbsp;nbsp;nbsp;hest-known of all extinct genera of Coniferae is Voltzia, Schpr,

als '-hsracteristic of the Trias and represented in the Permian formation by two species. The cones of Voltzia, which are frequently foundnbsp;J and even attached to the branches (see figures in Schimper^ andnbsp;and^^'^^ )gt; have the general habit of those of Abietineae ; they are cylindricalnbsp;, ^'d'^^posed of closely crowded spirally arranged scales, which appearnbsp;g �^3-tely to spread apart from one another. The stout woody scale�nbsp;ir'to'fT^^nbsp;nbsp;nbsp;nbsp;*rito a tolerably long stalk; the flat expansion divides above

jj nbsp;nbsp;nbsp;three obtuse terminations, on the back of which a corresponding

be nbsp;nbsp;nbsp;theie form a cushion-like elevation. On the upper inner side may

sha^^^'^ nbsp;nbsp;nbsp;well-preserved specimens a roundish areola inclosed by a

^arp beel-like ridge, to which are attached the edges con-esponding to the seeds'quot;^nbsp;nbsp;nbsp;nbsp;lobes. This areola is the plane of insertion of the dependent

^ ' Grand� Enry (1), nbsp;nbsp;nbsp;2 Renault (2), vol. iv, t. 4, f. 9.nbsp;nbsp;nbsp;nbsp;� Zeiller (3), t. 26, f. i.

'.3). t. 14. nbsp;nbsp;nbsp;5 Geinitz (2), t. 5.nbsp;nbsp;nbsp;nbsp;� Solms, Graf zu (1), and Geinitz (.2).

require renewed and careful examination. Of three species jgnbsp;nbsp;nbsp;nbsp;Stur r from the black slates of Raibl, one, V. raiblensis, Stur,

' to be characterised by scales having three lobes; it must therefore quot; He^ f ied to V. hexagona.

1^1*6 Lower Oolite of Siberia very similar in construction to those �Pec' �'^I�urgensis, Schaur. Schenk � has reproduced the figure of onenbsp;�rder^^'nbsp;nbsp;nbsp;nbsp;tl^'ri cone is clothed with quinquepartite scales in loose

needl' nbsp;nbsp;nbsp;distinguished by being developed from a short shoot without

the quot;^l^lch begins with scale-leaves, as in the silver firs and pines, whereas Seed^*^^-^nbsp;nbsp;nbsp;nbsp;Voltzias are placed on the summit of leafy branches,

on to each scale. He describes at the same place and figures the Snoots bearing a fascicle of long flat needles, which he considers tonbsp;j. '^^.^^Innged to the shoots because they were found near them. Thenbsp;be described by the same author as Schidolepium � (the name shouldnbsp;Co .^^*^�'^pldium) are so imperfectly known that we need not stay tonbsp;them. The genus Cheirolepis, Schpr, also is very like Voltzia innbsp;plantnbsp;nbsp;nbsp;nbsp;cone-scales. In this genus Schimper� has placed the

described by Schenk^ as Brachyphyllum Mtinsteri from the Rhaetic bayreuth. A second species, Cheirolepis Escheri, Heer, was after-^nbsp;nbsp;nbsp;nbsp;* found in the Lias �; the broad cone-scales scarcely narrow at all into

five nbsp;nbsp;nbsp;^nd are inciso-lobate on the upper margin. There are usually

So PP'^f^d lobes, the lateral ones being the broadest; but irregularities th'nbsp;nbsp;nbsp;nbsp;occur.nbsp;nbsp;nbsp;nbsp;The back of thenbsp;nbsp;nbsp;nbsp;scale, according tonbsp;nbsp;nbsp;nbsp;Saporta, shows a

tio nbsp;nbsp;nbsp;areola,nbsp;nbsp;nbsp;nbsp;which as usual henbsp;nbsp;nbsp;nbsp;considers to be thenbsp;nbsp;nbsp;nbsp;bract in conibina-

With the product of its axil. Two ovules are supposed to have been alwnbsp;nbsp;nbsp;nbsp;opposite side. Saporta further observes that the scales are

fhe^f ^�dnd isolated, and concludes that the cones have fallen to pieces. In fjygnbsp;nbsp;nbsp;nbsp;of thenbsp;nbsp;nbsp;nbsp;entire cone givennbsp;nbsp;nbsp;nbsp;by Schenk, which he says consists of

^d scales, nbsp;nbsp;nbsp;I can see nothing that resembles them.nbsp;nbsp;nbsp;nbsp;These remains of

quot;'Ith accompanied by copiously and irregularly ramifying branches fbatnbsp;nbsp;nbsp;nbsp;leaves spirally arranged ; but it is not certainly proved

genus Schizolepis, F. Braun, has elongated thin cones resembling ggt!^ Voltzia coburgensis, but of smaller size and with scales not closelynbsp;� �f this genus two w'eli-ascertained species are known from the Rhaetic

Schimper (1). nbsp;nbsp;nbsp;� Schenk (3).nbsp;nbsp;nbsp;nbsp;de Saporta (4). vol.

may have dropped, but it is also possible that it is really wanting, perhaps through arrest of growth. The seeds ^ are flattened, ovoid or elongated, andnbsp;girt by a narrow wing with an acute-angled notch at its apex. Such anbsp;structure of the cone, since there is nothing to indicate that the scale wasnbsp;double, affords no ground for placing the genus with Abietineae; we arenbsp;naturally led to a comparison with forms of the series of Araucarieae, andnbsp;in this comparison the flat scales seem to point to affinity with the typicalnbsp;Araucaria, the structure of the seed with Sequoia. We must remain innbsp;doubt on this point as long as we are in ignorance of the anatomicalnbsp;structure of the scales, for it is this which supplies the decisive characters.nbsp;Male flowers which have been found with specimens of Voltzia heterophyllanbsp;and V. recubariensis are strikingly like those of our pines. The abovenbsp;description of the cones of Voltzia is drawn from the best-known species,nbsp;V. Liebeana, Gein., and V. heterophylla, Brongn., in both of which conesnbsp;have been found attached to the branches. In V. heterophylla, a characteristic fossil of the Bunter Sandstone, very fine specimens of whichnbsp;have been found at Sulzbad in the Vosges, the shape of the leaves variesnbsp;much. Generally they resemble those of Araucaria excelsa, being bentnbsp;into the form of a curved thorn or hook from a decurrent base, but innbsp;places, especially at the summit of the branch, they are linear and acicularnbsp;and much elongated. Schimper^ has figured fine branches with both kindsnbsp;.of foliation. This latter form of leaf is the only or the prevailing onenbsp;in the Permian species V. Liebeana, Gein., of which splendid specimensnbsp;are found about Gera^. The Permian beds of Fiinfkirchen supply V.nbsp;hungarica, Heer * also, which resembles V. Liebeana but is distinguished bynbsp;the narrower lobes of the fertile scales, and the Rothliegende of Huckelheimnbsp;V. hexagona, Bisch.�, in which the cone-scales have only three lobes. Innbsp;both cases the scales are accompanied by branches with long leaves whichnbsp;have been generally supposed to belong to them, and which are in fact verynbsp;like the well-ascertained foliage of V. Liebeana. As we have V. hetero-phylla in the Bunter Sandstone, so we have V. recubariensis in the Lowetnbsp;Muschelkalk of the Southern Alps. Recoaro near Vicenza has suppliednbsp;abundant material, which has been examined by Schenk�. Here toonbsp;the characteristic cone - scales have been united to male flowers andnbsp;branches with short leaves solely on the strength of their all occurringnbsp;together, but the propriety of this is made more than probable by thenbsp;resemblance of the shoots to those of the species first considered. Anbsp;peculiar species, V. coburgensis, Schaur. (Glyptolepis Keuperiana, Schpr-))nbsp;occurs in the Keuper of Coburg. It is marked by long narrowly cylindricalnbsp;laxly-leaved cones in which the scales have their margins divided into many

� Solms, Graf zu (1), t. 2, ff, 29, 30, and Schenk (5), t. ii, f. i. � Schimper (3). nbsp;nbsp;nbsp;� Geinilz (2)-

beds, namely S. Braunii, Schenk \ from Franconia, and S. Follini, Nath.^ from Palsjo in Schonen. An older species founded on very fragmentarynbsp;remains, S. permensis, Heer, requires further verification. The scales of S.nbsp;Braunii, according to Schenk, are narrowed below; the seminiferous expansion is concave, and the upper margin is split into two ovate lobes. Henbsp;could see no indication of a differentiation into coherent fertile scale andnbsp;bract, and] therefore thinks that the genus belongs perhaps rather tonbsp;Abietineae. Saporta � on the other hand sees in the transverse boundingnbsp;line of the concave seminiferous expansion the apex of the bract-scale, whichnbsp;is overtopped by the adherent two-lobed fertile scale. Both authors affirmnbsp;that there are two seeds, and that the point of their insertion is marked onnbsp;the expansion of the scale by circular spots of a lighter colour. Of thenbsp;seeds themselves Saporta says that they are not winged, and, if I understandnbsp;his account aright, that they are erect. Schenk thinks that they are pendulous. I know not what is the foundation for these latter statements; as nonbsp;seed is anywhere figured, I incline to believe that they are conclusions fromnbsp;the position of the supposed points of insertion, which would certainly benbsp;quite inadmissible. The scales, at fii'st pressed against the slender axis ofnbsp;the cone, appear afterwards to spread. The cones of the other species,nbsp;similar in habit, would be distinguished according to Saporta ^ by havingnbsp;scales not narrowing downwards, but the figures, which are taken fromnbsp;plaster of Paris casts of the flat moulds on the slate-beds, are diagrammati-cally represented. According to Nathorst�s figures� we might almost doubtnbsp;whether these remains belong to the genus which we are considering, for innbsp;figures 4, 5, 6, and 8, between and by the side of the two-lobed forms,nbsp;broad scales may be seen with numerous furrows and terminal lobes likenbsp;those of Voltzia coburgensis. We might take the latter for the real cone-scales, and the two-lobed forms for the impressions of the two seeds whichnbsp;were attached to them, and which have been laid bare by fracture of thenbsp;stone. There are in this case therefore still a number of doubts to benbsp;removed; and while we are thus imperfectly informed respecting the cones,nbsp;we know nothing at all about the foliage of Schizolepis, for there is nothingnbsp;to make it even probable that the numerous needles which lie one abovenbsp;another in the beds at Palsjo, any more than the branches beset withnbsp;needle-bearing shoots which Schenk has referred to this genus, have anynbsp;connection with Schizolepis.

Heer � has described under the name of Inolepis some cone-bearing branches from the Urgonian Cretaceous formation of Greenland, whichnbsp;in the decussated arrangement of their scales have entirely the habitnbsp;of Cupressineae. The terminal ovoid cones, which unfortunately show

' Schenk (3). nbsp;nbsp;nbsp;^ Nathorst (2).nbsp;nbsp;nbsp;nbsp;= de Saporta (4).nbsp;nbsp;nbsp;nbsp;* de Saporta (4), vol. iii, t. I94-

' Nathorst (2), t. 15, ff. 4, 5; 6, 8. nbsp;nbsp;nbsp;' Heer (5), vol. 3 n, tt. 16, 23.

posed of spirally arranged scales, the rounded apex of the scale being ^ wked by thr ee deep longitudinal fold-like furrows. In this case thereforenbsp;char ^^csembling those of Cupressineae bear cones with the outwardnbsp;idnbsp;nbsp;nbsp;nbsp;Araucarieae, and we see again how careful we must be in

separate bits of branches. In the genus Cyparissidium, described Nnbsp;nbsp;nbsp;nbsp;from the Urgonian beds of Greenland and afterwards found by

orst in the Rhaetic beds of Schonen, the ovoid cones are composed ^ scales which have pretty much the shape of those of our pines, and arenbsp;asnbsp;nbsp;nbsp;nbsp;spirals and appear to be striated on the back. These cones,

the^ from a small fragment of wood preserved at the back of one of belong to branches which have close-pressed scale-like spirally ar-and irregular ramifications, and remind us of Widdringtonia.nbsp;sir!' �^cnilar branches also lie beside the cones of the Swedish Cyparis-^ �cptentrionale, Nath., so that supported by the case of Heer�s fossilnbsp;fairly assume that the two belong to one another. I cannot findnbsp;, the species recently described by Velenovsky � from the Cenomaniannbsp;^ of Bohemia, C. minimum, Vel., and C. pulchellum, Vel., agreed verynbsp;g ^^tiy with the structure of the cone in the original type. The genusnbsp;onolepidium, Heer (Sphenolepis, Schenk) is also very imperfectlynbsp;snnbsp;nbsp;nbsp;nbsp;the structure of the cone is altogether doubtful. The

g ^^�alden of Hanover Saporta � has described one very like them, srquemi, from the Rhaetic beds of the country round Metz. How farnbsp;new species from the Wealden of the North of Portugal reallynbsp;thnbsp;nbsp;nbsp;nbsp;genus I should be unwilling to say without examination of

. original specimens. The small spherical or ovoid cones appear in fas-g on the extremities of the branches ; they have the habit of those of oquoia and consist of spirally arranged scales, which become narrow and

, y open and spread out. According to Saporta the apex of the scale Posit' into a scutiform expansion, as in Sequoia; the number andnbsp;fornbsp;nbsp;nbsp;nbsp;seeds is altogether uncertain. Heer�s figures of his Portuguese

of ngree but little with Saporta�s and Schenk�s descriptions. The apex of scales appears to be longitudinally striated, and there is no indicationnbsp;scutiform terminal formation. We are not compelled however to con-cone^ there is certainly any essential difference, for the text says : �Thenbsp;strongly compressed, and it is very difficult to determine thenbsp;the scales.� When the palaeontologist speaks thus, every doubt is

� Heer 14^^' nbsp;nbsp;nbsp;*�'nbsp;nbsp;nbsp;nbsp;*� 5�t. S- * Schenk (1).

permitted to the botanist. The foliage of the Sphenolepidiae is spiral and close-pressed, or has the tips of the leaves spreading.

The genus Geinitzia, as far as is at present known with certainty, is peculiar to the Upper Chalk, for the specimens from the Tertiary formationsnbsp;of the New World cited by Schenk^ are still of too doubtful character tonbsp;come into question. Of this genus we have G. cretacea, Ung.^, from Neustadtnbsp;in Austria, O. formosa, Heer�, from Quedlinburg, and a fragment of a conenbsp;from the beds of Patoot in Greenland described by Heer ^ as G. hyperborea.nbsp;The cylindrical cones are distinguished by their unusually thick axis, whichnbsp;bears scales having a scutiform polygonal terminal expansion with a deepnbsp;umbo in the centre and radiating striae all round, and a central stalk ofnbsp;striking thickness which scarcely diminishes at all downwards. Heer�snbsp;statements with respect to the seeds attached to this longitudinally striatednbsp;stalk need further confirmation. That the branches found with these conesnbsp;belong to them is proved, at least in the case of G. formosa, by Heer�snbsp;figure which shows the two in connection. These branches are slendernbsp;and rod-like with few ramifications, and thickly covered with spiral leaves;nbsp;the bases of the leaves on the surface of the branch form rhombic areolae,nbsp;which are seen with special distinctness where the projecting falcately curvednbsp;apices are removed by fracture of the stone. A good figure of G. formosanbsp;is to be seen also in Schenk

Among the branches of Coniferae from the lithographic limestone of Solenhofen, besides the above-mentioned forms of Cupressineae and thenbsp;Brachyphyllae which will be noticed again presently, cone-bearing branchesnbsp;are found which retain the name of Echinostrobus Sternbergii originallynbsp;given by Schimper to these remains collectively. The chapter in Saporta �nbsp;on this point should be consulted. The branches, figured in Schenk *, arenbsp;pinnately ramified and clothed with closely crowded short scale-like leavesnbsp;attached by a broad rhombic base, much as in the modern genus Arthro-taxis, on which account the fossil form was named by Unger Arthrotaxitesnbsp;lycopodioides. The cones are spherical, and their mode of preservationnbsp;is such that only the external form can be discerned. Each of the component scales ends in a stout thorn-like process. Saporta would place thenbsp;genus near Arthrotaxis; he also thinks that Swedenborgia a peculiarnbsp;Conifer from the Rhaetic beds of Schonen of which nothing has been knownnbsp;hitherto except cones with the habit of those of Cryptomeria, belongs tonbsp;the same alliance. These cones, which are evidently over-ripe and fallennbsp;from the trees, are ovoid in shape, and their scales stand out at a right anglenbsp;from the axis. The single scale is wedge-shaped and narrowed into thenbsp;long stalk, and has the upper margin usually divided into five acute three-

� Zittel (1). nbsp;nbsp;nbsp;^ Unger (4).nbsp;nbsp;nbsp;nbsp;= Heer (16).nbsp;nbsp;nbsp;nbsp;�* Heer (5), vol. vii I, t. 51, f. 13.nbsp;nbsp;nbsp;nbsp;= Heer

(15), t. 2, f. 5. nbsp;nbsp;nbsp;� Zittel (1), p. 299.nbsp;nbsp;nbsp;nbsp;' de Saporta (4).nbsp;nbsp;nbsp;nbsp;* Zittel (1), p. 302.nbsp;nbsp;nbsp;nbsp;� Nathorst (2)-

but these numerical relations are not constant. According g _^Porta the middle tooth would answer to the bract, the others to thenbsp;j. erous adherent apex of the fertile scale. We are still in uncertaintynbsp;^^specting the seeds; Nathorst speaks of a single seed, but not withoutnbsp;Citation, and also gives a figure of it ^ ; Saporta maintains that therenbsp;several.

'T'l

but ^ Palissya, Endl., is greatly in want of more thorough elucidation, Ijttj�nbsp;nbsp;nbsp;nbsp;localities have ceased to yield specimens, there is unfortunately

ha ^ nbsp;nbsp;nbsp;1^0 be learnt after Schenk�s repeated examinations �. The name

been given to an assemblage of remains of Conifers, consisting of cones ofnbsp;nbsp;nbsp;nbsp;character, with seeds and branches from the Rhaetic formation

^ ranconia; some leafy branches also from Schonen are referred by to the, same group, but whether rightly or not can hardly benbsp;annbsp;nbsp;nbsp;nbsp;since the genus is so uncertain. Two species, P. Braunii, Endl,

th nbsp;nbsp;nbsp;Sch., are described, but they resemble each other so little

jj. ^^Porta � proposes to remove the latter from the genus and approximate Sphenolepis ; Schenk � however protests against this arrangement, which

issya Braunii is made up of cones, branches, and seeds found near one aj.nbsp;nbsp;nbsp;nbsp;^nd apparently united together for this reason only. The branches

*-be form of thin rods with very acuminate narrow flat needles loosely spirally arranged. It does not appear to me quite certain that thenbsp;all belong to the same plant. Schenk figures one cone with spread-5 scales attached to the moderately thick axis, and at the same placenbsp;fio- �fhers with the scales closed. In the former case he has also givennbsp;^bUres of tire separate parts � showing the position of the seeds ; his scalesnbsp;^ flat, elongate-lanceolate, acuminate, the lower portion of the lateralnbsp;being rendered pinnate by the presence of short lobe-like projectionsnbsp;upwards. I can confirm this representation from examination ofnbsp;In^ specimens in the Geological Department of the British Museum.

the cylindrical closed cones, on the other hand, we can only see Vvli� lanceolate scales lying one over the other. In one of themnbsp;_ u is crushed and in which we might expect to see the lateralnbsp;apparent, and this throws doubt on the con-jj.The figures of detached seeds also given by Schenk in thenbsp;thnbsp;nbsp;nbsp;nbsp;places differ from one another in not unimportant points, and

'�^^��efore appear to me doubtful. In stating that the scale bears Schenk refers, as appears from his work to the above-*oned lateral projections, which appear in the figures of the parts as

� nbsp;nbsp;nbsp;(4).nbsp;nbsp;nbsp;nbsp;2 Nathorst (2), t. i6, f. ii.nbsp;nbsp;nbsp;nbsp;Schenk (3) and (8), and Zittel (1), p. 334.

Saporta (4), vol. iii, p. 512. nbsp;nbsp;nbsp;' Zittel (1).nbsp;nbsp;nbsp;nbsp;� Schenk (3), t. 41, f, 9,

T), p. 335. nbsp;nbsp;nbsp;8 Schenk (8), and Zittel (1), p. 336.nbsp;nbsp;nbsp;nbsp;^ Zittel (1), f. c. Schenk (8).

highly convex seeds of very irregular form ; he says nothing at all on this point in his very brief original account of these fossils b The same circumstances are explained in a different manner by Saporta, who defines thenbsp;genus from the expanded cone, though Schenk protests against this proceeding. Schenk in this case, as in most others, assumes the presence ofnbsp;two scales which have become united to one another; in Palissya thenbsp;fertile scale reaches beyond the bract-scale not with its apex but laterally,nbsp;and the lobes are supposed to answer to so many projecting sections of itsnbsp;margin. These again are constructions for which the facts do not supplynbsp;the needful material.

Palissya aptera is the name given by Schenk to some branches having spirally arranged scale-like leaves and bearing cones. The terminal ovoidnbsp;cones are formed of crowded lanceolate sharply-keeled scales, and are totallynbsp;different in habit from the preceding; nothing is known of their innernbsp;structure. Small elliptical bodies found on the slabs are without furthernbsp;reason taken to be the seeds. If we are still desirous of giving a generalnbsp;definition of the genus Palissya, we must confine ourselves with Saporta tonbsp;the form of cone which at least shows its peculiar characters, and disregardnbsp;the doubtful P. aptera. It is also a question whether the branches withnbsp;acicular leaves really belong to the Palissya-cones.

There are two more forms of cones which may be mentioned here, though their connection with the Coniferae is not above suspicion. Saporta ^nbsp;has de.scribed under the name of Entomolepis Cynarocephala, Sap. annbsp;elliptical cone from the Miocene beds of Armissan eight centimetres in length,nbsp;in which the large broad scales are firmly closed one on another, and thenbsp;apex of the scale runs out into a strongly developed spreading deeply inciso-dentate leaf-like appendage. This cone is also noticed by Renault^ andnbsp;Schenk And in the Geological Department of the British Museum a slabnbsp;was shown me which came from Solenhofen with the Haberlein collection,nbsp;and which has on it a remarkable impression named by Thiselton Dyer �nbsp;Condylites squamatus. Dyer has no doubt that we have in this impressionnbsp;the remains of a Conifer, and he was at first inclined to compare it withnbsp;Cupressineae. Several branches lie side by side on the slab; these arenbsp;sympodially developed, and terminate each with peculiar usually four-lobednbsp;bodies which may recall the cones of Callitris. Two slender innovation-shoots arise on a branch beneath the extremity which bears these bodies-That the plant is a Conifer may be concluded from the presence here andnbsp;there on the branches of crowded scutiform spirally arranged rhombic leaf-cushions, such as we see in Arthrotaxis. Dyer also conjectures that somenbsp;of the sterile branches from Solenhofen which are classed with Arthrotaxites

^^^^�ocyparis may belong to this form. One feels tempted to see same plant, but in an inferior state of preservation, in Saporta�s ^ alralnbsp;'S Itieria, a specimen of which I have seen in the collection of the �colenbsp;^s Mines at Paris, and which belongs to the Middle and Upper Oolite,nbsp;found in the Coralline Oolite of St. Mihiel and in the Kimmeridgenbsp;Orbagnoux.

Finally, there remain yet two genera which, as the fructification is j- .nbsp;nbsp;nbsp;nbsp;entirely unknown, are founded exclusively on characters of the

and therefore are to a high degree provisional only. There is first thnbsp;nbsp;nbsp;nbsp;Schpr a fossil peculiar to the Bunter Sandstone, and up to

� present time scarcely found anywhere but in the Vosges, and there uy in the great quarry at Sulzbad near Strassburg, which is unfortun-y gt;^0 longer worked. The bilaterally ramifying branches bear spirallynbsp;arranged spreading flat leaves, which above the broad line of insertion havenbsp;�Poon-Iike concavity and are rounded off at the upper extremity, and shownbsp;delicate longitudinal striation. They are commonly compared with thenbsp;^ ves of Dammara, but are essentially distinguished from them by thenbsp;�^d plane of insertion. Cones, which were assumed by Schimper tonbsp;ong to these branches, are described by him as ellipsoid in shape andnbsp;ScU^^ of simple ovoid scales; each scale is said to have one winged seed,nbsp;'niper certainly had no perfect cone before him when he constituted thisnbsp;or he would have figured it and not been content with describingnbsp;^Constructions only. Subsequently the Museum of Strassburg actuallynbsp;h k- ^ cone answering to the description and having very much thenbsp;of a cone of a pine. This cone is still there, but shows no trace ofnbsp;denbsp;nbsp;nbsp;nbsp;I do not know therefore on what Schimper founded his

P cgt;f Cordaiteae which will be considered presently. In this remark-c specimen leaf-like scales have in their axils other scales, which bear Un* ^nbsp;nbsp;nbsp;nbsp;of stamens with their numerous sessile elongated anthers

^ fascicles (anth�res sessiles tr�s allong�es nombreuses fascicul�es,

second important genus characteristic of the Permian formation is

cscript�Qj^ of them, and since it is not attached to a leafy branch, its con-*^cction with Albertia is altogether arbitrary and unsupported ; the supposed flower figured by Schimper has been determined by Schenk � after re-^^^mination of the original to be a young cone of Voltzia. A variety ofnbsp;appear to have been distributed under this designation, for Renault ^nbsp;a similar male flower, also from Sulzbad, which if it belonged tonbsp;sh ^ould certainly separate that genus entirely from Coniferae; wenbsp;�^ld in that case do much better to seek for objects of comparison in the

WalchiaIn the most common species, W. piniformis, Sternb., the branch-systems, which show numerous ramifications disposed in two lines and are often found in actual connection, have thoroughly the habit of Araucarianbsp;excelsa, and are studded all round with short falcate or hooked leavesnbsp;arranged in spirals. Other branches, which may however possibly belongnbsp;to the same species, have no leaves with hooked extremities, while othersnbsp;again, which are properly regarded as belonging to a distinct species, W.nbsp;filiciformis, Sternb., have their leaves less closely set and not covering thenbsp;branch as with scales. The individual leaves, strongly hooked and havingnbsp;a stout almost conical cushion, stand out at nearly a right angle from thenbsp;branch. G�ppert ^ says that the leaves have several nerves, but as he appealsnbsp;only to the striation as seen on the surface from which we cannot concludenbsp;directly as to the course of the nerves, we must not attach any importancenbsp;to the statement. All these branches are thus united under Walchia solelynbsp;from their external appearance, and it is quite possible that they belongednbsp;to very different genera ; and we begin to suspect that it was so, when wenbsp;consider the different organs of fructification which authors have assignednbsp;to this genus. Bergeron for instance, has figured a branch of Walchianbsp;from the schists of Lod�ve with terminal cylindrical cones on the lowest ofnbsp;its pinnate lateral ramifications, and as the scales have dropped from one ofnbsp;the cones, the axis only remains showing the points of attachment. Thenbsp;scales in these cones are imbricate and spirally arranged, and each scale isnbsp;lanceolate at the apex ; the structural details are not known. Weiss ¹ hasnbsp;made us acquainted with a somewhat less perfect fragment of the samenbsp;kind ; the unattached cones had been before described by different writers,nbsp;G�ppert� for example and Schimper�. Bergeron�s specimen, like a similarnbsp;one from Lod�ve in my possession, bears its well-developed cones on longnbsp;branches, and between them other cones on short shoots in a younger state.nbsp;But when he concludes from this that the cone-bearing branches werenbsp;developed later, after the vegetative branches, perhaps from resting buds,nbsp;we must object that young cones may cease to develope at an early age, andnbsp;that such imperfect growths are often found in our living species on weaklynbsp;shoots which were developed at the same time with the rest.

On the other hand. Grand� Eury� has described and figured a branch of Walchia from the bituminous schists of Autun, in which the lower of twonbsp;perfectly preserved lateral branches bears ovoid carpoliths in the axils ofnbsp;its leaves, while the upper has in the same situation small closed buds composed of many not clearly defined leaves. The former objects he considersnbsp;to be the seeds, the latter the male flowers of the plant, which according tonbsp;the foliation would be referred without hesitation to Walchia. His brief

Sternberg, Graf von (1). nbsp;nbsp;nbsp;¹ G�ppert (3), p. 238.nbsp;nbsp;nbsp;nbsp;= Bergeron (1).nbsp;nbsp;nbsp;nbsp;¹ Weiss (1), t. i7-

' G�ppert (3). nbsp;nbsp;nbsp;� Schimper (1), t, 73.nbsp;nbsp;nbsp;nbsp;� Grand� Eury (1), p. 514,

l^ernarks contained in a note are agreeably supplemented by Renault who had opportunity of examining the original specimen. This authornbsp;�3-ys that there can be no doubt about the axillary seeds, which are ovoid,nbsp;�ur to five millimetres in length, and suddenly and finely acuminate ; theirnbsp;^ind of coal encloses a nucleus of pyrites. The little buds of the other branchnbsp;also converted into pyrites, and Renault has not been quite able tonbsp;satisfy himself that they are male catkins. Somewhat similar remains tonbsp;l^ose described by the French authors have been noticed by G�ppert ^;

*s figure shows the extremity of a branch from which numerous small P'^oid seed-like bodies are dropping; the other figure shows numerous budsnbsp;the axil of a leaf, which may be compared with the similar forms fromnbsp;branch in question. Lastly, Renault � gives the name of Pseudowalchianbsp;'quot;ondosa to a branch of some species of Walchia from Millery near Autun,nbsp;which ovoid seed-like bodies are terminal on the extremity of the branch,nbsp;he himself does not lay much weight on this solitary specimen.

If Walchia is very open to the suspicion of being an artificial and P^'ovisional collection of heterogeneous remains of similar habit, it is quitenbsp;'�^'^tain that this is the case with the genus Pagiophyllum, Heer (Pachy-Phyllum, Sap.), which we must now consider. The name is given tonbsp;^'anches with closely crowded spiral usually short but sometimes elongatenbsp;^^ceolate leaves springing from decurrent leaf-cushions,� such branches asnbsp;^¹'6 of frequent occurrence especially in the Mesozoic formations. The leavesnbsp;often more or less strongly keeled on the back, and show numerous rowsnbsp;pinhole-like stomata. A number of species from the Trias, the Jurassicnbsp;System, and the Chalk will be found cited in Schenk ^ ; the Jurassic speci-^ens are discussed at length by Saporta �. Older authors, who may benbsp;'Consulted in Saporta�s work, usually call them Araucaritae. Whether thenbsp;^olenhofen cone figured by Saporta � really belongs to his Pachyphyllumnbsp;^'dnicum is uncertain; the same may be said of the scales found by Pomelnbsp;quot;'dh P. rigidum, Sap., in the Infra-Liassic beds of Metz. Even if it werenbsp;'luite certain that they belong to P. cirinicum, they could only inform usnbsp;'�oticerning the fructification of that species ; the fructification might benbsp;^^'te different in other species. It is only in accordance with old customnbsp;distinguish the Ullmanniae of the Zechstein from Pagiophyllum, as I havenbsp;^^deavoured to show elsewhere^. The genus Ullmannia was originallynbsp;Established by G�ppert � by arbitrarily uniting together certain branchesnbsp;^'^d Cone-like objects; the branches had been for the most part describednbsp;y the older writers as Caulerpites and Fucoides. As they are sometimesnbsp;PEtrified in calcium carbonate, it has been possible to determine the

Renault (2), vol. iv, p. 88. nbsp;nbsp;nbsp;� Goppeit (3), t. 49, ff. tn �3-nbsp;nbsp;nbsp;nbsp;,

P- ns. nbsp;nbsp;nbsp;= de Saporta (4).nbsp;nbsp;nbsp;nbsp;� de Saporta (4), t 180.

anatomical structure of the leaves. These are one-nerved in all the species, and their vascular bundle is accompanied on both sides by a broad transfusion-wing composed of reticulate tracheides. Hypodermal fibres arenbsp;frequent, differently distributed in the different species. Ullmannia Bronnii,nbsp;known by the name of Frankenberg copper-spikes, occurs in the cupriferousnbsp;clays of Frankenberg in Hesse in small fragments of leafy branches, whichnbsp;are the centres of formation of the copper-glance, and were thereforenbsp;formerly the object of mining operations in the district. Their crowdednbsp;shortly linguiform leaves scarcely differ from those of other ordinary speciesnbsp;of Pagiophyllum. Two or three other forms, Ullmannia selaginoides,nbsp;U. frumentaria, and U. orobiformis have more elongated leaves; those ofnbsp;U. frumentaria are acute and slightly keeled on the back, which is crowdednbsp;with stomata; in the two other species they are almost cylindrical andnbsp;rounded at the tip. They occur frequently in the form of impressions innbsp;the Kupferschiefer of many localities, especially of Gera ; as petrifactionsnbsp;in calcium carbonate with their structure preserved they are found onlynbsp;near Ilmenau in Th�ringen imbedded in nodules. From the latter specimensnbsp;we learn that U. frumentaria had distinct parallel subepidermal strands ofnbsp;fibres, while in the two other species a thin continuous fibre-layer is foundnbsp;in the same position. The facts are stated the reverse way by an oversightnbsp;in Schenk \ and the synonym U. lycopodioides is placed with U. selaginoides,nbsp;whereas it belongs to U. frumentaria. Elliptical or ovoid cone-like bodies arenbsp;found in large numbers both at Frankenberg and Gera, made up of lanceolate scales and resembling in habit those first described under the head ofnbsp;Walchia. Cones of the kind have been found at Gera attached to branchesnbsp;of U. frumentaria^, but unfortunately we know nothing of their structure.nbsp;They are variously figured by Geinitz Peculiar scales also are found innbsp;Frankenberg which are sometimes united into cone-like aggregations, andnbsp;in this state they were considered by G�ppert to be the fructification ofnbsp;Ullmannia ; as it is not certain that they belong to Coniferae, I have givennbsp;them the name of Strobilites Bronnii, which does not prejudge the question.nbsp;These scales are circular with an umbo on one face, and have the thickenednbsp;margin embellished with radiating furrows ; on the other face is a shortnbsp;central stalk round which, when the preservation is unusually good, a girdlenbsp;of areolae may be observed, each with a minute round protuberance at itsnbsp;centre. These are doubtless the scars of deciduous organs, perhaps ofnbsp;seeds. I may refer the reader to my treatise already mentioned for furthernbsp;details respecting these questionable remains.

Branches and branch-systems from the Mesozoic deposits, having much the habit of Arthrotaxis, have been named by Brongniart Brachyphyllum.

eir leaves disposed in. spirals and touching one another are all alike, and unusually abbreviated; the basal portion is developed in the form ofnbsp;a polygonal shield with a central boss ; the apex is very obtuse, and beingnbsp;'usually curved inwards is thus withdrawn from observation, but in somenbsp;^^ses it assumes a larger growth, and then it is not easy to distinguish thenbsp;s^nches from Pagiophyllum. A dot-like often conspicuous protuberancenbsp;the back of the shield appears to answer to an oil-gland occupying thenbsp;�^nie place here as in our Cupressineae. Many Jurassic forms are to benbsp;^'nd figured in Saporta k The fructification of these coniferous branchesnbsp;scarcely be said to be known ; Saporta indeed figures some ellipticalnbsp;^ones which in habit do to some extent resemble those mentioned undernbsp;^Ichia : he also, as is usual with him, indulges in a variety of conjecturesnbsp;��pecting their structure which is but indistinctly shown; but still he doesnbsp;prove that they really belong to the branches of B.rachyphyllum Jau-and B. Moreauanum, near which they were found at Verdun andnbsp;Chateauroux. Heer ^ has found spherical cone-like bodies attached to thenbsp;extremities of the branches of his B. insigne from the Lower Oolite ofnbsp;^'beria, which are composed of polygonal scales like those of the branchesnbsp;'�^ernselves, but there is nothing by which we can judge of their internalnbsp;eharacter. A figure of this conjectural fruit of B. insigne is to be found innbsp;efienk together with an enumeration of all the described species, but thisnbsp;^�uld not be of any interest in this place.. It may be mentioned thatnbsp;^^Porta has determined one species, B. nepos, from among the coniferousnbsp;^^nches from Solenhofen which were included by Schimper in his genusnbsp;^uinostrobus. These remains are present in abundance in the Middle andnbsp;^Pper Oolite of France and England ; among them is B. mamillare, Brongn.,nbsp;^ona Scarborough.

We must mention in conclusion the genus Camptophyllum described Nathorst^ from the Rhaetic beds of Schonen, though the author himselfnbsp;^��ards it as a fossil mcertae sedis. The remains are small portions ofnbsp;'�inches with a stout axis, and flat acicular leaves bent backwards in anbsp;Peculiar manner and forming an arch.

The small fragments of branches beset with scale-like leaves, and also � small acicular leaves with two longitudinal keels, which Sterzel �nbsp;Scribes as Dicalamophyllum Altendorfense from the hornstones of thenbsp;^thliegende of Chemnitz, are of quite doubtful character,nbsp;j The surface of primary and other branches of Coniferae without theirnbsp;^^Ves appear also to have been preserved here and there in impressions ornbsp;^^sts; but as it is perfectly impossible to say in the case of any of thesenbsp;that they certainly belong to Coniferae, we need not cite in this

place the particular notices of them to be found in the literature. But I should wish briefly to mention one fossil at present in danger of beingnbsp;forgotten, the connection of which with the Coniferae seems to have beennbsp;well established by means of sections prepared from a silicified fragment.nbsp;I allude to Tylodendron speciosum, Weiss found originally in the sandstone of the lowest beds of the Rothliegende at Ottweiler near Saarbrticken,nbsp;together with much silicified wood, and afterwards detected by Zeiller ^ innbsp;the Permian beds of la Corr�ze near Brive. Weiss associates with it variousnbsp;similar casts of branches described and figured by Eichwald � which comenbsp;partly from the Carboniferous limestone, partly from the Permian depositsnbsp;of Eastern Russia. His own figures of Tylodendron speciosum show straightnbsp;branches without ramifications as much as seventy centimetres in length,nbsp;resembling the topmost shoots of Conifers, and everywhere covered withnbsp;narrow rhombic convex spirally arranged leaf-cushions, each of which shows anbsp;groove-like impression in its upper portion. The branches swell at regularnbsp;intervals and become fusiform, and the lower half of the swollen part isnbsp;marked by the great abbreviation of the cushions on its surface, exactly innbsp;the manner usually to be observed in our pines at the extremity of thenbsp;annual shoot where it is covered with bud-scales. Our knowledge of thenbsp;anatomy of the plant is imperfect, but Weiss gives a radial section whichnbsp;shows exactly the picture of one of the coniferous woods which are classednbsp;with Araucaroxylon, and thus we have proof that the fossil belongs to thenbsp;group under consideration.

It is well known that fragments of wood having the structure of living Conifers are found in every state of preservation throughout the entire seriesnbsp;of geological formations from the middle Devonian upwards, and that theynbsp;begin to be common everywhere as early as the higher members of thenbsp;Coal-measures. Great hopes therefore have long been entertained thatnbsp;their examination would supply important results and points of departure.nbsp;To G�ppert^ must be assigned the first place in the cultivation of this fieldnbsp;of research. Owing however to the uniformity of structure which characterises secondary growth in thickness in Coniferae, these efforts have notnbsp;been crowned with that measure of success which might have been expected.nbsp;P'irst of all it has become apparent that other groups, very near the Coniferae it is true but still distinct from them, as for example the Palaeozoicnbsp;Cordaiteae, possess a woody structure so like that of Coniferae, that it isnbsp;impossible to distinguish them unless we have entire sections of a stemnbsp;before us. Further, G�ppert has perceived that it is only in the rarestnbsp;cases that we can distinguish the genera within the class by the structurenbsp;of the wood, and that oftentimes even the members of different families

Weiss (1), p. 185. Zeiller (4), t. S, f. i. ^ Eichwald (1). nbsp;nbsp;nbsp;* G�ppert (5) and (4).

cannot be thus separated. In this way he arrived at the formation of the groups of woods known as Pinites, Araucarites, Cupressinoxylon, and Taxites,nbsp;^ first of which takes in most of the recent Abietineae, the second thenbsp;raucarias and Dammaras and with them the Cordaiteae, as was saidnbsp;^ove, the third the Cupressineae and Podocarpeae, the fourth the Taxineae.

o these were added the generic types Physematopitys answering to the quot;'Ood of Ginkgo, Protopitys which doubtless represents one of the woodsnbsp;uncertain affinity now named Arthropitys, which will be noticed againnbsp;presently, and the altogether doubtful Spiropitys. Unfortunately G�ppertnbsp;converted the groups of woods thus obtained into genera, and foundednbsp;^�^rnerous species within them on characters which are in some cases verynbsp;*^oubtful. His main results have since been gathered up by Kraus ^ andnbsp;�^fended by splitting' Pinites into Pityoxylon and Cedroxylon, the first ofnbsp;quot;'fiich takes in the firs, the second the rest of the Abietineae. Kraus hasnbsp;3-lso carefully examined the characters employed in the definition of species,nbsp;has shown that the relative marks generally made use of up to thatnbsp;breadth of the annual ring, width of the cell-lumina, thickness of thenbsp;^^11'Walls, number of rows of pits on the radial walls of the tracheides,nbsp;^'ght of the medullary rays and their frequency, can either not be employednbsp;^11 or only with the extremest caution, because, as von Mohl ^ has shown in

^ell-known treatise, they are liable to important modifications in the erent organs of the same tree, in stem or branch or root, and becausenbsp;individual fluctuations occur in different trees of the same species,nbsp;h.ssner � has supplied ample proof of the truth of these remarks as respectsnbsp;�dumber and height of the medullary rays, and Kraus '* himself showed, bynbsp;application of diagnoses in G�ppert�s manner, in the case of the connectednbsp;and branch of a piece of wood from the lignite of the Rhon, thatnbsp;the two had been found separate they would have supplied twonbsp;��od species. The characters of Kraus� generic groups are as follows : i.nbsp;�^^^aucaroxylon (Dadoxylon, Endl.). Radial pits of the tracheides eithernbsp;one row with contact and mutual compression, or alternating in severalnbsp;and becoming polygonal from mutual contact. Medullary rays in anbsp;^''^gle row on the tangential section. 2. Pissodendron. Distinguished fromnbsp;^raucaroxylon only by the presence of several rows of medullary rays,nbsp;^'tham 5 calls such forms Pitus, Brongniart � Palaeoxylon. 3. Cupres-��^ylon. Radial pits of the tracheides in a single row, circular, notnbsp;'�'^^ching one another, or in several rows very commonly in the root exceptionally in the stem, not alternating and polygonal but round and innbsp;quot;quot;'�egular transverse rows. Resiniferous parenchymatous wood-cells in

Schimper (1), p. 363. H. von Mohl, Einige anatomisch-physiologische d)nbsp;nbsp;nbsp;nbsp;iiber das Holz der Baiimwiirzeln (Bot. Ztg. (1862), p. 22j).nbsp;nbsp;nbsp;nbsp;� Essner (1).nbsp;nbsp;nbsp;nbsp;* Kraus

� t�- 185. nbsp;nbsp;nbsp;5 Witham '1).nbsp;nbsp;nbsp;nbsp;� Brongniart (2).

greater or less abundance. Medullary rays simple. 4. Pityoxylon. Tra-cheides as in Cupressoxylon. Resin-passages besides the parenchymatous wood-cells, but still surrounded by secretion-tissue. Medullary rays of twonbsp;kinds ; those in several rows with a resin-passage running horizontally throughnbsp;their centre. 5- Cedroxylon. Exactly as Cupressoxylon, only without resin-iferous wood-parenchyma. 6. Taxoxylon. Distinguished from Cedroxylonnbsp;merely by the well-known spiral striation which projects on the innernbsp;surface of the wall of the tracheides, but which must not be confoundednbsp;with the annular and spiral striation in the substance of the membranenbsp;common in the autumn-formed tracheides of coniferous woods.

We might think that it would be easy to discover and apply the above differential characters in fossil woods, but the task is not unaccompaniednbsp;with difficulties. For instance, it is not always quite easy to separate thenbsp;wood of the roots of Cupressoxylon and Cedroxylon with pits in severalnbsp;rows (Eleoxylon, Brongn.^) from Araucaroxylon, and the distinguishing thenbsp;Araucaroxyla with pits in a single row from the other two groups may havenbsp;its perplexities ; and hence we see Pinites latiporosus, Cramer referred bynbsp;Kraus� to Araucaroxylon, and by Schr�ter^ to Cedroxylon. Again, thenbsp;difference between Cupi-essoxylon and Cedroxylon is obscured by thenbsp;circumstance that in some Cupressineae the wood contains an unusuallynbsp;small number of resiniferous cells, of which Beust gives many examplesnbsp;Individual as well as specific variations have their effect, so that we cannbsp;scarcely feel quite sure that there are no such variations to be taken intonbsp;account. It is also easy to mistake tracheides anomalously filled withnbsp;resin for parenchymatous wood-cells, and difficult to distinguish the latternbsp;in the sections when, as often happens, they contain no resin ; nor must allnbsp;brown substances filling the cells in fossil woods be supposed to be resinnbsp;without careful examination; the presence or absence of the excretion innbsp;the wood of Ginkgo, for example, is still in dispute, as will appear by comparing the statements of Kraus and Beust.

Attempts have lately been made to establish further distinctions between fossil woods founded on the characters of the medullary rays-Kraus � had already used these characters to break up Pityoxylon, and thenbsp;process was thoroughly carried out in this group by Schr�ter^. From wantnbsp;of personal experience as regards the constancy of all these characters I amnbsp;not in a position to criticise the results of these efforts, and I must refer thenbsp;reader to the original literature. At the same time I would point out thatnbsp;all of them, not excepting Kleeberg�s � which is the most recent, suffer fromnbsp;a fault in method which ought to have been avoided after the appearancenbsp;von Mohl�s and Kraus� publications ; the obsei'vers have pursued their investi'

' See Conwentzfl) and (2). nbsp;nbsp;nbsp;� Heer (5), vol. i, t. 40.nbsp;nbsp;nbsp;nbsp;� Sdiimper (1).nbsp;nbsp;nbsp;nbsp;* Heer (5)gt;

vol. 6IV, p. 9. See also Felix (1), p. 4, upon Rhizocedroxylon Hoheiieggeri. nbsp;nbsp;nbsp;'' Beust (1)�

� Schiraper (1). nbsp;nbsp;nbsp;� Heer (5), vol. 6 IV.nbsp;nbsp;nbsp;nbsp;� Kleeberg (1).

gations extensively instead of intensively. It is difficult to see the use of descriptions of all sorts of fragments of wood from the collections, thoughnbsp;'-hey may include hundreds of exotic species, so long as we are ignorant ofnbsp;'�he limits of variation within the species and the individuals. Far morenbsp;profitable would be a comparative examination of a few species based onnbsp;abundant material from all parts of the plants, for this alone can give thatnbsp;Sure foundation without which our conclusions are precarious and oftentimesnbsp;the air. Such a mode of proceeding would be all the more obvious,nbsp;because the value of the whole of these laborious investigations would benbsp;^ry doubtful, if the statements before us were shown to be strictly correct.nbsp;�According to Schroter, all species of Abies, with two exceptions, belong bynbsp;'�he structure of their wood to Cedroxylon, Abies Welbiana only agreeingnbsp;^'th Cupressoxylon and A. Pindrow with the first sub-form of Pityoxylon.

this sub-form he also places Pinus longifolia, Roxb,, while all other pines belong to the second and third sub-forms. If this is so, how can we expectnbsp;'�^ conclude with any show of justification from the anatomical structure ofnbsp;^voods that they belong to any particular divisions of our system.? And itnbsp;as a rule only slightly probable that we shall find pieces of wood in actualnbsp;Connection with leafy branches and cones, though this may happen once nownbsp;^nd then. The only instance known to me in which this method of deter-^'nation was pursued is supplied by Schenk h He found in the lignites ofnbsp;^urzen in Saxony large cones and leafy branches of Sequoia Couttsiae,nbsp;^cer, and with them larger branches and stems, and he determined thenbsp;Connection of the latter with that species on the strength of their agreementnbsp;structure with the leafy branches. Felix ^ subsequently decided that thenbsp;'''oody fragments belonged to Cupressoxylon Protolarix, G�pp.

According to the statements of authors, Kraus� especially, Taxoxyla at present known only from thfe Tertiaries, Cupressoxyla have beennbsp;^ound in the Chalk, Pityoxyla and Cedroxyla as far down as thenbsp;^cuper. Araucaroxyla and Pissodendra are the only woods whichnbsp;cccur in the older formations, if we put put of sight the two doubtful kindsnbsp;otn the Coal-measures known as Pinites Conwentzian�s, G�pp.''^, and Pencenbsp;Fhami, Lindl. and Hutt.� The latter is referred by Renault to Araucaro-^ylon, by Kraus to Cedroxylon. The figure would allow of either con-clusion ; Kraus� view implies that the specimen is a piece of wood from the

Only fresh examination of the original can decide the question. To 9-ucaroxylon belong also the pieces of wood described by Dawson � fromnbsp;Middle Devonian beds of Canada and New Brunswick, Dadoxylonnbsp;uangondianum, D. Hallii, D. Newberryi and Ormoxylon Erianum G. and

belong to Cordaitae. It has been already stated that the Cordaitae show the structure of Araucaroxylon, and that they include a large portion ofnbsp;the palaeozoic woods. But that there were also true Conifers with thenbsp;same wjoody structure in the Carboniferous and Permian eras is provednbsp;from the descriptions given of Tylodendron speciosum, Weiss Thenbsp;hitherto doubtful Aporoxylon primigenium, Ung.^, from the Cypridina-schists (Upper Devonian) of Saalfeld has recently been unmasked bynbsp;G�ppert � through the discovery of radial pits most of which had disap-pearedj and has been determined to be an Araucaroxylon.

Under the names of Prototaxites Logani and Nematoxylon cras-sum Dawson ^ has described silicified wood from the Lower Devonian beds of Canada and New Brunswick, entire stems of which were observednbsp;in the cliffs of Little Cape Oiseau near Gasp�, as the oldest known coniferous remains. Pieces in which the structure is preserved show circularnbsp;transverse sections of cells not arranged in any order, and separated fromnbsp;one another by homogeneous partition-walls of unusual thickness. Thenbsp;longitudinal section shows that their substance is composed of very longnbsp;uniform tubes which appear to bend irregularly hither and thither and tonbsp;intertwine, and not to run in regular and parallel lines as in normal wood ofnbsp;Conifers. The spiral striation, on account of which Dawson chose thenbsp;name Prototaxites, has however nothing in common with Taxus ; the thicknbsp;wall is seen in the longitudinal section to be traversed by striae, narrownbsp;tubes, confusedly interwoven. His bordered pits look more like cross viewsnbsp;of these striae. Carruthers to whom we are indebted for an exact accountnbsp;of the matter, finds no resemblance to the structure of coniferous woods,nbsp;and thinks that Prototaxites must be considered to be an alga-stem. Inbsp;have satisfied myself by examining preparations of material supplied bynbsp;Dawson himself that the fossil has little in common with Coniferae; it maynbsp;possibly be an Alga, but I can find no direct analogue for it among thenbsp;forms known to me, and Halimeda and similar plants suggested by Carruthers can scarcely be brought into the comparison. Stems of Fucaceaenbsp;with growth in thickness as represented by Reinke might at first perhaps benbsp;thought of, but these differ in not unessential points from the descriptionsnbsp;of Prototaxites. The same form, or one absolutely similar, has very recentlynbsp;been found in Wales in the much older Silurian beds of the Upper Land-overy formation in the shape of small silicified partly brown, partly coal-black fragments cemented into the rock, and showing the described structurenbsp;most beautifully. These plant-remains, which are named Nematophycusnbsp;Hicksii, Eth.�, are without doubt the very oldest in which the structure stillnbsp;preserved can be clearly seen.

IV.

The remains of Cycadeae attain their greatest development in the ^lesozoic formations, especially in the series of beds of the Jurassic system ;nbsp;^here can be no doubt that they were generally distributed during thatnbsp;Period of time over the northern hemisphere. Comparatively few Palaeozoic forms are known, and most of these are remains of stems from thenbsp;Permian formation and from the Coal-measures. Undoubted leaves ofnbsp;Cycadeae have been found but very rarely in both these systems, and havenbsp;'^cen described and figured in Saporta and Marion ^ (Pterophyllum Grand�nbsp;^uryanum, Sap. et Mar., and Sphenozamites Rochei, Ren.^) from the Coal-measures of St. Etienne and Autun, in Geinitz � (Pterophyllum Cottaeanum,nbsp;^ein.) from the Rothliegende of Zwickau, and in Sandberger ^ (Pterophyl-iuni blechnoides, Sandb.) from the Upper Coal-measures of Oppenau innbsp;�aden. A leaf also which is said to come from the Coal-measures ofnbsp;Eastern Russia is figured in Eichwald� and named Pterophyllum inflexum,nbsp;Eichw., and Renault and Zeiller� mention a Zaraites carbonarius from thenbsp;^egt;al of Commentry. Several others described by G�ppert �� are not abovenbsp;^^spicion.

The Cycadeae are still tolerably numerous in the lower Chalk, but ^Ifer the Cenomanian beds the group diminishes greatly in importance.nbsp;E must not however be forgotten that the Tertiary flora is really knownnbsp;any great extent only in Europe and perhaps in the Arctic Zone,nbsp;mgions in which Cycads no longer live, and from which they may havenbsp;Smdually disappeared during the period of the Chalk. That theynbsp;still to be found in the South of Europe in Tertiary times, thoughnbsp;�'V in number, is shown by some single specimens from the Lower

locene ; we have, for example, Zamites epibius, Sap.�, from Bonnieux the Department of Vaucluse and Encephalartos Gorceixianus, Sap.�,nbsp;Eom Kumi in Euboea, both represented by leaves which certainly have the

Saporta et Marion (2), p. 109. nbsp;nbsp;nbsp;' There is a mistake in the explanation of the woodcuts in

^ ^ Work, that which is said of B referring really to A, and vice versa. nbsp;nbsp;nbsp;^ Geinitz (1) and (4).

, ^Endberger ^l). nbsp;nbsp;nbsp;amp; Eichwald (1), vol. i, t. 15.nbsp;nbsp;nbsp;nbsp;Zeiller (11).nbsp;nbsp;nbsp;nbsp;quot; G�ppert (7).

^ ��^aporta (2), p. 116. nbsp;nbsp;nbsp;de Saporta (2), p. 116, an (lo), p. 298.

Casts of detached seeds, which from their size and shape may properly be Considered as Cycas-seeds (Cycadeospermum hettangense, Sap.). And ifnbsp;We are anywhere justified in concluding that parts belong to one anothernbsp;tgt;ecause they are found lying together in the same place, we are so here,nbsp;Where the consideration of the whole of the circumstances leads almost ofnbsp;Necessity to the same conclusion.

But in the case of all other remains of Cycads from the prehistoric World we have no grounds for concluding that they are affiliated to livingnbsp;forms. Here therefore we can only adopt confessedly artificial genera fornbsp;fhe stems, leaves and remains of flowers, and arrange our material in thesenbsp;According to such external characters as we can recognise in it. In dealingnbsp;With the leaves which have first to be considered, it is unfortunate that theynbsp;clo not of themselves enable us to distinguish between Ferns and Cycadsnbsp;With absolute certainty. Neither the shape of the expanded part, nor thenbsp;ooiirse of the nerves, nor the form of the epidermal cells can decide thenbsp;fliiestion. It is true that the epidermal cells are usually polygonal withnbsp;straight side-walls in Cycads and with arcuately curved walls in Ferns, butnbsp;the genus Stangeria agrees with the Ferns in this respect and was originallynbsp;'described by Hooker as Lomaria. Schenk therefore, who like Borne-Wiann^ attempted to determine the nature of the leaves from this character^,nbsp;has since ceased to employ it The structure of the vascular bundlesnbsp;^ight possibly have supplied a certain criterion, but this is unknown, asnbsp;there are no petrified specimens ; the only resource left us is the habit,nbsp;^nd this, as the case of Stangeria sufficiently shows, may mislead us. Sincenbsp;the determination of all these remains rests on so insecure a foundation, wenbsp;'Cannot be surprised that some of them have been shifted backwards andnbsp;forwards by different authors from Cycads to Ferns and from Ferns tonbsp;f^ycads. Of such forms it will be well to select the genus Otozamites, Fr.nbsp;f^raun (Otopteris, Ldl. and Hutt.) for consideration in this place, and tonbsp;hiscuss a number of others, N�ggerathia, Sternbg, Thinnfeldia, Ettingsh.,nbsp;ffichopteris, Zigno, Cycadopteris, Zigno-, Nilssonia, Brongn., later on withnbsp;fhe Ferns.

Older authors, like Brongniart were content with a few genera for the ��Oception of their fossil forms. As the value of these genera was purely con-'^ontional, this was wisely done. The later multiplication of genera, in whichnbsp;S^eat weight was attached to details of character, has become the fruitfulnbsp;Source of endless synonymy and transference of species, and thus the generalnbsp;''lew has been obscured, while little has been gained in the way of deeper in-�'ght into the nature of the remains. A full description of all these genera,nbsp;'''hich have little interest for the botanist, is to be found in Schimper A fewnbsp;^'^rnarks founded on Brongniart�s observations may be sufficient in this place.

appearance of belonging to recent genera, though the connection cannot be certainly proved. To these must be added a cone-like flower supposed tonbsp;belong to the Cycadeae, Zamiostrobus Saportanus, Schpr, from Armissannbsp;in the South of France. No remains of Cycads have been found by Heer innbsp;the rich Miocene flora of the Polar regions, for Nilssonia serotina, Heer^nbsp;from Sagalien may be a Fern.

The genus Cycas is a singular type without any near relatives in modern vegetation. Fossil forms teach us that this type is one of greatnbsp;antiquity. We find leaves with all the characters of those of Cycas, copiousnbsp;pinnation and linear pointed pinnae with only one nerve, in all formationsnbsp;down to the Rhaetic. From the Chalk may be mentioned Cycas Steen-strupii, Heer^, and C. Dicksoni, Heer^, both from the Urgonian bedsnbsp;of Atane in Greenland; from the Wealden C. R�meri, Schenk^, fromnbsp;the Jurassic beds C. zamioides and from the same formation innbsp;India C. Rajmahalensis, Oldh., C. Blandfordianus, Oldh.�, C. constrictus,nbsp;Feistm.^, C. Lorteti, and other species¹; from the angulatus-beds ofnbsp;the Lias C. pectinatus, Berger ¹; from the Rhaetic formation C. rectangu-laris, Braun If the small leaf-fragment named by G�ppert C. taxo-dinus really belongs to this family, and having seen the original specimennbsp;from Rothwaltersdorf in Silesia I do not in fact know where else it can benbsp;placed, the type will have existed as early as the Carboniferous limestone.

But though these leaves are so characteristic and so like those of our modern Cycas-forms, yet we could not venture on the strength of themnbsp;alone to ascribe so great antiquity to the recent genus. But this conclusionnbsp;is supported by the carpophylls, which like the leaves are frequently metnbsp;with and are easy of recognition, and agree in all essential points with thosenbsp;of Cycas revoluta. A carpophyll in splendid condition lies on the samenbsp;slab with the Cretaceous Cycas Steenstrupii, Heer, and has the ovules stillnbsp;in situ on the extremities of the lower pinnae. The original specimens ofnbsp;two similar fossils fl'om the Coralline Oolite of Sommedieu near St. Mihiel,nbsp;are unfortunately lost; the figures of them are to be seen in Saporta withnbsp;the name of Cycadospadix Moreauanus, Sap. At the same place in Saportanbsp;and also in Schenk i¹, will be found an account of similar remains (Cycadospadix Hennoquei, Schpr) which occurred repeatedly in the angulatus-bedsnbsp;of Hettange and Coburg. It is true that in most of these cases only thenbsp;extremities of the carpophylls are preserved, but they are as.sociated withnbsp;the before-mentioned leaves (C. pectinatus, Berger) and with very many

Heer (5), vol. 5 III, t. 2. nbsp;nbsp;nbsp;^ Heer (5), vol. 6II, t. 5.nbsp;nbsp;nbsp;nbsp;= Heer (5), vol. 3 ii, t. 28, and vol.

6 II, 1.16. nbsp;nbsp;nbsp;¹ Schenk (1), t. 32.nbsp;nbsp;nbsp;nbsp;� Leckenby (1), t. 8.nbsp;nbsp;nbsp;nbsp;� Pal. Ind., ser. II, vol. i, pt. i, tt. 7, 8, 9-

� Pal. Ind., ser. H, vol. i, pt. iv, t. 7. nbsp;nbsp;nbsp;� de Saporta (4), vol. ii, tt. 12, 13.nbsp;nbsp;nbsp;nbsp;� Berger (!)�

See also G�ppert (8). nbsp;nbsp;nbsp;� Schenk (3), t. 35.nbsp;nbsp;nbsp;nbsp;� G�ppert (7). de Saporta (4), vol. ii, t. 116.

In the type of Pterophyllum, Brongn., the ribbon-like pinnae, which are all of the same breadth and are obtuse at the extremity, form a right anglenbsp;with the rhachis, being inserted upon it exactly perpendicularly to it onnbsp;both its sides, and are often connected with one another by a narrownbsp;border; the nerves run in parallel straight lines. The well-known Pterophyllum Jageri, Br. from the Keuper may be mentioned as an example.nbsp;Certain forms of this type, as P. Schaumburgense, Dunk, from thenbsp;Wealden are distinguished by very short and broad almost quadratic, andnbsp;often unequal pinnae, and are known by the name of Anomozamites.nbsp;To the Pteroph3dlae belong also, according to Schenk^, the remains of largenbsp;leaves from the Keuper of Raibl in Carinthia which he names P. giganteum ;nbsp;they were first called N�ggerathia vogesiaca by Bronn ^ and ultimatelynbsp;appear in Schimper � as Macropterygium.

In the Zamitae the pinnae articulate with the rhachis and separate from it in certain circumstances, but this is not possible with the Pterophyllae.nbsp;Their numerous nerves, which sometimes form a single dichotomy, runnbsp;parallel with one another and with the margin of the pinnae, and appear to unitenbsp;with one another at their e'xti'emities to form a marginal nerve, as happensnbsp;in the recent Ceratozamia. In true Zamitae the pinnules are sharp-pointed atnbsp;the apex, narrowed and abruptly rounded at the base, and are attachednbsp;obliquely to the axis which they overlap and cover. In the Podozamitaenbsp;they are more wedge-shaped, have the upper extremity broad and roundednbsp;off, and are said to be attached perpendicularly to the axis. When theynbsp;are found isolated and detached from the axis, and this appears to be oftennbsp;the case, it is not easy to identify them, and they may be mistaken fornbsp;portions of other similar elongated parallel-nerved leaves, for those ofnbsp;Phoenicopsis for example, or even for leaf-segments of Baiera and Ginkgo.nbsp;This is still more true of Rhiptozamites which is only known in the formnbsp;of isolated pinnae. The genera N�ggerathiopsis, O. Feistm., and Eury-phyllum, O. Feistm., which are also placed with Cycadeae, will be considered again further on with the Cordaitae. Finally, the name Glosso-zamitae has been given by Schimper to certain forms of this type whichnbsp;resemble the Pterophyllae in habit, but must be carefully distinguishednbsp;from them. Zamites Feneonis, Br.� from the Upper Oolite, and especially frequent in the Coralline Oolite of the neighbourhood of Lyons,nbsp;may be mentioned as the best-known species of true Zamitae; as annbsp;example of Glossozamitae I should name Glossozamites Zittelii, Schprnbsp;and of Podozamitae Podozamites distans, PresL� Numerous figures ofnbsp;leaves of Podozamitae are moreover to be found in Heer* and Nathorst�.

� Schenk (7). nbsp;nbsp;nbsp;^ Bronn (1).nbsp;nbsp;nbsp;nbsp;�� Schimper (2).nbsp;nbsp;nbsp;nbsp;* Schmalhausen (1\ p, 29, tt. 4, i,'-

�� Ettingshausen (2), t. 3. nbsp;nbsp;nbsp;� Schenk (4), t. 8.nbsp;nbsp;nbsp;nbsp;� Schenk (3\ tt. 35, 36, 37.nbsp;nbsp;nbsp;nbsp;� Heer (5)-

The Otozamitae also have articulating pinnae which narrow at the ^ase and overlap and cover the axis. Each pinna has on that side of thenbsp;base which is towards the apex of the leaf a more or less stronglynbsp;*ieveloped projecting ear-like lobe, which has suggested the name of thenbsp;genus. The bases of all the pinnae when seen from the upper side and thenbsp;'�hachis also, if the condition is strongly marked, are covered by the auriclesnbsp;the pinnae next below them : the pinnules all lie like scales one onnbsp;Another. The character is less prominent on the under side where thenbsp;*'hachis is visible, because the latter partly hides the auricles. The appear-^^ce therefore of the same leaf is quite different according to the positionnbsp;which it lies on the slab, and this must be considered in determiningnbsp;'^bese forms. The nervation also is essentially distinct from that of thenbsp;^amitae, and corresponds with the nervation of Neuropteris and Cyclopterisnbsp;defined by Mettenius for the Ferns. Numerous nerves run in curvednbsp;bnes diverging and occasionally dividing dichotomously to the margin ofnbsp;'�be leaf, so that the whole nerve-system is flabelliform in appearance. Itnbsp;true that these characters are not so striking to the eye in all the formsnbsp;the type, as they are, for example, in Otozamites brevifolius, F. Braun hnbsp;O. Bunburyanus, Zigno^, and many others. As the auricles of the basalnbsp;Extremities diminish in size, the fan-shaped nervation always becomes lessnbsp;distinctly marked. Forms of this character, which are named Ptilophyllum,nbsp;Morris, are especially common in the Jurassic deposits of India, and arenbsp;further distinguished, according to O. Feistmantel by the decurrence ofnbsp;'be pinnules on the axis. The British Museum possesses beautiful speci-'^^uns of this kind. Countless figures of them are to be found in Feist-�^Untel�s work just quoted, and in the Palaeontologia Indica^. In Schenk�,nbsp;has been before said, the forms of this type are given among the Ferns,nbsp;Purtly on account of the structure of the epidermis, partly and chieflynbsp;I^Ecause the author became acquainted with a leaf found by Beneckenbsp;Southern Tyrol and very like O. Bunburyanus, Zigno, in which thenbsp;b'Unae showed on their under side a thickened seam-like margin. Henbsp;Considers that this is the margin of the pinnule recurved as in Cheilanthesnbsp;covering the sori ; but he has not been able to produce anythingnbsp;^Ecisive in support of this view. It may possibly be correct; the differencenbsp;utween the leaves of Ferns and Cycads are so minute that it is not incon-^E'vable that remains from both classes may have been placed with thenbsp;Q^Egt;zamitae. In connection with this point the form named by Saporta �nbsp;^zamites marginatus may also be compared.

Of the flowers of Cycadeae only a few remains have been discovered, the greater number of these are in an indifferent state of pre-

servation. The carpophylls of Cycas have been already mentioned. A male flower found in the Lower Oolite (Cornbrash) by Etrochey andnbsp;described by Saporta ^ as Androstrobus Balduini appears only as anbsp;surface-impression. In the cast of the cavity Sapotta saw the pollen-sacsnbsp;in large numbers between the scale-tips, which are rhombic on the transverse section, in a position answering to the inferior margin of each scale.nbsp;The flower appears therefore to have been buried after it was fully developed,nbsp;and judging by the figure we may say without hesitation that it presentsnbsp;the essential characters of our genus Cycas. Another fossil described bynbsp;Saporta ^ and named Androstrobus Gu�rangeri, Brongn., from the Cenomanian deposits of Le Mans, is of much more doubtful character, and doesnbsp;not appear to offer much resemblance to Dioon with which it is compared.nbsp;The genus Frisia also must be noticed in this connection, which Vele-novsky� has recently described from the Cretaceous strata of the Whitenbsp;Mountain near Prague. Of this genus we have a variety of broken conesnbsp;bearing scales on their thick central axis. The scales form polygonalnbsp;surfaces where they close on one another, and narrow gradually downwardsnbsp;into the slender point of attachment; and round their lateral surfaces theynbsp;have small depressions which are considered by Velenovsky to be remainsnbsp;of pollen-sacs. There is lastly the obscure form which has been named bynbsp;Heer * Androstrobus sibiricus.

Of female flowers or fertile cones the first which demands our notice is Beania a remarkable genus but certainly belonging to the present group-Beania gracilis, Carr., from the Upper Oolite of Gristhorpe in Yorkshire, shows two-seeded carpophylls which agree perfectly in form with thosenbsp;of our Zamias. The notable point in this fossil is simply the enormousnbsp;elongation of the internodes of the floral axis, which removes the fertilenbsp;leaves to a great distance from one another. Schimper � compares with itnbsp;a fossil also from Gristhorpe, which Lindley and Hutton �� have figured aSnbsp;Sphaereda paradoxa. The comparison is apt; the original which I havenbsp;seen in the Museum at Oxford agrees well with Beania. Some remains ofnbsp;fruit in a very bad state of preservation, found in two separate pieces in thenbsp;Lower Lias of Arlon in Belgium (angulatus-beds) and possibly not evennbsp;belonging to one another, have been described by Saporta � as ZamiostrobuSnbsp;Ponceleti. The seeds which have been preserved show at all events thatnbsp;the specimens are fruits, and these may possibly belong to our presentnbsp;group. Velenovsky� gives a full account of the fruit-remains formerlynbsp;described by Corda as Microzamia gibba from the Cretaceous formationnbsp;of Bohemia. The stalked scales, polygonal above and scutiform where the/

' de Saporta (t), vol. ii, t. 115. nbsp;nbsp;nbsp;� de Saporta (4), vol. ii, t. 78.nbsp;nbsp;nbsp;nbsp;= Velenovsky (1', p. �, t. 3-

� Heer (5), vol. 411, t. 4. nbsp;nbsp;nbsp;� Carruthers (3).nbsp;nbsp;nbsp;nbsp;� Schimper (1).nbsp;nbsp;nbsp;nbsp;� Lindley and Hutton (1)�

vol. iii, t. 150. nbsp;nbsp;nbsp;� de .Saporta (4), vol. ii, t. 117.nbsp;nbsp;nbsp;nbsp;� Velenovsky (1), tt. 3, 4.nbsp;nbsp;nbsp;nbsp;Reuss (C�

close upon one another, are supposed to have borne two seeds on the under �'de, but this does not appear from the figures, which seem to show thenbsp;�ceds irregularly disposed. The flowers are supposed to have been crowdednbsp;together to form racemose inflorescences, and in this respect they departnbsp;'^cry essentially from our recent forms. Much greater doubt appears to menbsp;rest upon a fossil form which Nathorst has described as Zamiostrobusnbsp;�l^enorhachis, and Saporta and Marion ^ have figured. That it is the fruit ofnbsp;^odozamites is merely an arbitrary assumption. Androstrobus borealis,nbsp;^ath.2, and Zamiostrobus orientalis. Heer�, are objects of quite uncertainnbsp;�Mature ; the latter is a single scale and is said to be without question a cone-�cale of Cycadeae or Abietineae. Lastly, a large number of entire cone-I'ke bodies showing the surface only have been described as forms ofnbsp;�'Zamiostrobus, and will be found enumerated in Schimper^. Some of themnbsp;Probably belong to the group which we are considering, for example Zamio-�trobus Saportanus, Schpr from the Miocene beds of Armissan, which isnbsp;^gured in Saporta and Marion In this case a long thick stalk has beennbsp;preserved which bears the ovoid cone. Where this is wanting, we remainnbsp;a rule in doubt whether we have before us the fructification of a Cycadnbsp;�r of a Conifer, or only a small stem of a Cycad encircled by the leaf-bases,nbsp;^^sts of seeds, which are often assigned by authors to the Cycadeae, are innbsp;S^neral incapable of determination. Seeds will not be of any interest tillnbsp;Succeed in finding them in such a state of preservation that we cannbsp;�^amine into their inner structure. The remarkable fructification ofnbsp;^nnettites, Carr., can only be discussed in connection with the stemsnbsp;quot;'hich bear it; and we must therefore consider them together. For William-^'^nia, which is placed by English authors with the Oolitic Zamites gigas,nbsp;*�^6 reader is referred to another section of this work.

Stems of Cycad�ae in large numbers have long been known in the Jurassic (Purbeck beds) and Wealden especially in England and France,nbsp;Partly as casts, partly silicified and with the surface more or less perfectlynbsp;P*'eserved. Similar silicified stems are found not only in England andnbsp;�^^nce but also in Silesia and in North Italy as rolled blocks in alluvium,nbsp;may be supposed to have belonged originally to the same formations,nbsp;j^^'^eral of these rolled stems are preserved in the Museum of Bologna,nbsp;^^ving been found with vases and other utensils in the sepulchral chambersnbsp;^^the necropolis of the ancient Felsina ; they had evidently been buried bynbsp;Etruscans as objects of superstition with their dead. It has beennbsp;eady observed that the leaves of Cycadeae disappear as we ascend in thenbsp;fonbsp;nbsp;nbsp;nbsp;formations, and the stems also disappear in like manner. I have

the figures, one described by Brongniart^ as Endogenites echinatus, from the coarse limestone of the Eocene deposits of Soissons, and anothernbsp;Cycadites Escheri, Heer from the Molasse of Stein near Schaffhausen. Onnbsp;the other hand, stems and fragments of stems occur in the Upper Coal-measures and in the Rothliegende in Saxony, Bohemia, the neighbourhoodnbsp;of Autun, and in the Ural Mountains, the structure of which points to theirnbsp;affinity with the Cycadeae, while the surface-characters cannot be recognisednbsp;at all or only imperfectly. Since Cotta�s � time they have been known asnbsp;Medullosae, and they must be noticed again when the Mesozoic forms justnbsp;mentioned have first been considered.

As a rule the Mesozoic stems of Cycadeae, which, as was said, are shortly cylindrical or roundish and tuber-like in form, show only thenbsp;characters of their surface, which is covered as in living species with closelynbsp;crowded spirally disposed leaf-bases and scale-leaves. The form andnbsp;surface characters of the stems were used to limit the purely conventionalnbsp;generic groups, to which Saporta has given entirely new names, becausenbsp;those previously in use, Mantellia, Brongn., Bucklandia, Brongn., Clathraria,nbsp;Mantell, included many remains not belonging to the group, and were in somenbsp;cases founded upon them. Saporta places all tuber-like and spherical stemsnbsp;with their clo.se armour of scales and leaf-scars which are rhombic on the crossnbsp;section in his genera Bolbopodium and Clathropodium. These genera arenbsp;represented by a considerable number of species and vary much in size. Ifnbsp;they are small we may easily be in doubt, as has been already said, whethernbsp;we are dealing with stems or fruits, as for example in the greater part ofnbsp;the remains figured by Carruthers ^ as Cycadostrobus. C. Brunoni, Carr., ofnbsp;unknown origin, is the only certain cone, but it looks more like a cone ofnbsp;Araucaria than of Cycadeae. In some forms figured by Saporta � the ringnbsp;of wood is clearly to be seen when the fossil is broken across, as in Clathro-podium Trigeri, Sap., found near Le Mans but not in its original place ofnbsp;deposit, and in C. Sarlatense, Sap., also a stray object picked up neatnbsp;Sarlat in the Dordogne. To judge from the figure there might be severalnbsp;consecutive rings of wood in this stem, as in old specimens of Cycas, andnbsp;this point should be attended to in any further examination of the fossil-Its medulla is of remarkably small diameter. The stem described bynbsp;Carruthers as Bennettites Saxbyanus is also referred by Saporta tonbsp;Clathropodium, and this from his stand-point is quite justifiable. But thisnbsp;stem does really belong to Bennettites, Carr., for though the lateral axesnbsp;so chai'acteristic of this genus are not to be seen in the figure, yet Car-ruthers states that they are a general feature in all the species, and I havenbsp;satisfied myself by personal examination that they are present in the three

original specimens of B. Saxbyanus, Carr. Clathropodium Trigeri, Sap., quot;'hich I examined in the Paris Museum, also proved to be a stem of Ben-oettites.

Elongated cylindrical stems encircled by a similar armour of leaf-^9^ses are called by Saporta, Cylindropodium and Platylepis. The latter ^arne is given to forms in which the surfaces of separation are very broadnbsp;^od flat. The same stems are named by Carruthers Bucklandia, Yatesianbsp;and Mantellia. Cylindropodium liasinum, Sap., from the Lower Lias ofnbsp;L�n�viller, though badly preserved, shows the outlines of its woodynbsp;Cylinder. Lastly, in Fittonia, Carr. Saporta includes all those stemsnbsp;'n which the enveloping leaf-bases, narrowed into the shape of a conenbsp;finger and touching one another only at the base, bear the comparatively small scar of separation at their apex. Besides the speciesnbsp;^gured by Saporta and Carruthers this genus also includes the cyca-quot;^aceous stem from the Wealden of Bantorf near Hanover, whichnbsp;^chenk^ has figured as Clathraria Lyellii. Figures of stems resemblingnbsp;^ylindropodia and Fittoniae, and said to have been found in the Permiannbsp;^^rmation of Eastern Russia, will be found in Eichwald a. Fresh examina-'�^on of this author�s original specimens is required in this as in many othernbsp;'^ases.

Certain cone-like casts from the Cenomanian Chalk of Bohemia, named �y Velenovsky^ Krannera mirabilis, have recently been declared by himnbsp;'�0 be stems of some form of plant allied to Cycadeae. They were formerlynbsp;'Considered to be cones, and have been described by Presl � under the namenbsp;'cf Dammarites albus, by G�ppert � under that of D. crassipes. Thesenbsp;*0ssils are globular bodies beset with scales arranged in spirals, each scalenbsp;showing a transverse scar of separation on the inner side of its uppernbsp;�^nrgin. Fragments of parallel-nerved leaves are in a few cases stillnbsp;attached to the seal', showing that the scales must be regarded as woodynbsp;^Oaf-bases. These cone-like bodies are sometimes borne on thick stalksnbsp;'harked with leaf-scars, and are therefore believed by Velenovsky to benbsp;^^0 shortened thickened extremities of cylindrical leafy stalks. From thenbsp;�^ornains of the leaves found attached to the scales he suspects that tonbsp;'�^ese cones belong certain parallel-nerved simple ribbon-like leavesnbsp;'''hh obtuse terminations common in the same locality, which werenbsp;Erroneously determined to be Flabellaria chamaeropifolia, G�pp. andnbsp;��Egarded as shreds of palm-leaves. Velenovsky inclines to compare themnbsp;rather with Cordaites, Phoenicopsis or Podozamites, or still better with

, de Saporta (4), vol. ii, t. Ii8. � Schenk (1), t. 14. nbsp;nbsp;nbsp;� Eichwald (1), vol. i, tt. 17, iS.

^ ^lenovsky (1), t. 4. nbsp;nbsp;nbsp;� .Sternberg, Graf von (1), Heft 5-8, t. 52, ff. ii, 12.nbsp;nbsp;nbsp;nbsp;� G�ppert (4), p.

45- nbsp;nbsp;nbsp;^ Velenovsky (1), t. i.nbsp;nbsp;nbsp;nbsp;^ Schmalhaiisen (1), t. 15, ff. i-ii.

is correct, and the figured specimen certainly favours it then Krannera cannot be classed immediately with Cycadeae. The certain determinationnbsp;of its affinities must in any case depend on the discovery of fresh specimens. Lastly Velenovsky takes some globular casts, which show thenbsp;place where a stalk has been broken off from them on one side, for thenbsp;seeds of Krannera, solely because they were found with it. The onlynbsp;Cycad, as far as I know, in which the stem with the leaves attached cannbsp;be determined with certainty, is Zamites gigas, Morr. The specimen ofnbsp;this plant came from the Upper Jurassic sandstone of Yorkshire, and wasnbsp;obtained from its owner James Yates for the Paris Museum, where I saWnbsp;it. A figure of it is given by Saporta^. The stem bears a lateral budnbsp;enveloped in handsome leaves ; in this respect and in habit also it recallsnbsp;Stangeria. It appears also to have been quite naked, though Saportanbsp;contends that he has discovered traces of scales and places it among hisnbsp;Cylindropodia. It has been already mentioned that English authorsnbsp;consider the peculiar flowers known as Wiiliamsonia, Carr, to belong tonbsp;Zamites gigas. Williamson� mentions a second similar but less perfectnbsp;specimen. He would also place in this species the stems covered all roundnbsp;with leaf-scales which he found near Scarborough; but from a specimennbsp;which I saw in Oxford I should say that they are the stems of Ferns.nbsp;The specimens it is true lie on the same slab with several leaves of Zamites,nbsp;but no conclusion can be drawn from this circumstance.

Carruthers^ has described a veiy remai'kable stem covered with fructifications by the name of Bennettites Gibsonianus (Fig. 5). It is sili'nbsp;cified, and in a wonderful state of preservation, and comes from thenbsp;Lower Greensand of the Isle of Wight. Carruthers shows first ofnbsp;all that all the remains known as Bennettites have a distinctly ellipticalnbsp;and not a circular cross section, though they have not been subjected tonbsp;any particular pressure. The pith, which has no cauline bundle-system,nbsp;is surrounded by a simple secondary woody ring of great thickness, whichnbsp;is divided by numerous tolerably broad medullary rays into portions ofnbsp;unequal size. The rather narrow rind is enclosed in a compact armoufnbsp;of leaf-bases in the same manner as in Clathropodia and Cylindropodia-At the same time there are considerable intervals between the separatenbsp;members, and these are filled up with a thick mass of hair-formationSnbsp;resembling paleae. The fusiform transverse sections of these paleaceousnbsp;scales � show one or two cell-layers lying one above the other. The leaf'nbsp;bases themselves are rhombic in form on the cross section and containnbsp;numerous vascular bundles in the neighbourhood of the periphery, which

� Schmalhaiisen (1), t. 4, f. 4. nbsp;nbsp;nbsp;� lt;3e Saporta (4), vol. ii, t. 81.

form a broad horse-shoe arrangement open above and with very short shanks inclined inwards. In some cases the parenchyma has partiallynbsp;disappeared (rotted out) on the surface of separation, and then the leaf-bases appear from the outside as rhombic cavities surrounded by a projecting network, which is formed by the silicified epidermal layers andnbsp;fhe masses of paleaceous hairs lying between them. Similar conditionsnbsp;of preservation occur also in other stems of Cycadeae, as, for example,nbsp;'n Clathropodium foratum which may pei'haps belong to Bennettites andnbsp;'vhich derives its name from them, and in Raumeriae also which will benbsp;noticed again further on.

But in Bennettites this armour of leaf-bases is pierced by many lightly-closed flowers or inflorescences, which surrounded by numerous leavesnbsp;force their way through it and come to the surface, and there owing to thenbsp;nubbing off of the tips of their leaves between the surfaces of separation of thenbsp;ieaf-bases appear in the form of peculiar centrically constructed whorls. Itnbsp;is at present uncertain whether these organs arise as axillary buds, thoughnbsp;this is in itself probable; some other points also connected with theirnbsp;structure are still undetermined, notwithstanding Carruthers� excellentnbsp;^nd searching examination of this fossil. The courtesy of Messrs. Car-'�uthers, Hooker and Thiselton Dyer has put me in a position to makenbsp;^ fresh examination, and this has already cleared up some of these questionsnbsp;a satisfactory manner. I must however reserve descriptive details fornbsp;the connected account of the stem, which I design to give. The entirenbsp;�object is attached to the rind of the stem by a thick stalk, which is sur-�'ounded by lanceolate leaves^ and repeats even the details of the structurenbsp;'^f the stem on the small scale, showing only some irregularity of shape in thenbsp;Ifansverse section in many places, due probably to pressure. The leaves alsonbsp;^hich encircle it are distinguished from the before-mentioned leaf-bases ofnbsp;fhe main axis only by the smaller and constantly decreasing size of the trans-''erse section. The stalk terminates in a flatly convex cushion, which Inbsp;Conclude to have been of a fleshy succulent character because its tissuenbsp;been wholly destroyed, and consequently nothing can be perceivednbsp;the preparation before me but confused macerated parenchyma-cells andnbsp;bagments of vascluar bundles. From the upper surface of the cushionnbsp;^bere arises a bundle of closely crowded polygonal stalks in an envelopenbsp;several layers of linear-lanceolate leaves ; the stout cortical parenchymanbsp;these stalks has protected them from decay, and forms a sheath roundnbsp;^be small vascular bundle which lies in the middle of a gap in the tissue,nbsp;between these stalks and Ailing small interstices are seen other transversenbsp;^^ctions, each of which conceals a vascular bundle (Fig. 5 C). Whether

* lt;^6 Saporta (4), vol. ii. � Carruthers (4), t. 58, ft. 5 and 3. nbsp;nbsp;nbsp;�� Carruthers (4), t. 59, f. 3.

CVCADEAE, MEDULLOSEAE.

these bundles belong to stalks similar to the others and lying between them but arrested in their development, as I suspect is the case, I have not yetnbsp;certainly established. The members of the tuft diverge above and increasenbsp;in thickness. Thus arises an elliptical cone with a nearly even surfacenbsp;formed by the perfect cohesion of the apical portions of all the constituentnbsp;members (Fig. 5 A). The seeds, which in the specimens examined appearnbsp;to be perfectly ripe, are present in large numbers and form a superficialnbsp;layer in the cone. Each of them occupies a small cavity which communi-

Fig. 5. Fructification of Bennettites Gibsonianus, Carr. A diagrammatic representation of the fructification-cone. Its thick leafy stem enlarges at the apex into a succulent cushion, from which ri.se a crowded tuft of numerous stalklike objects, each traversed by a vascular bundle ; the stalks unite with one another at the periphery and form a continuous surface. Each stalk bears at its apex a seed which lies in a pocket-like depression. B representation of thenbsp;longitudinal section of a seed, to some extent diagrammatic and constructed from several distinct figures ; a the enteringnbsp;vascular bundle ; � its expansion at the base of the nucellus; c the embryo with the two cotyledons ; d the testanbsp;formed of stout lignified palisade-like cells, which is prolonged above into a tubular process d' terminating obtuselynbsp;on the surface of the cone, and probably answers to the integument; e tubular cell-layer, the continuation of a delicatenbsp;membrane surrounding the embryo, and possibly answering to the outer boundary of the nucellus ; the tubular processnbsp;at its apex represents the apex of the nucellus surrounding the pollen-chamber. C portion of the transverse sectionnbsp;through the tuft of seminiferous stalks beneath the place where the seeds begin (��a in the diagrammaticnbsp;representation of the entire cone); at a the transverse sections of the enveloping lanceolate leaves which springnbsp;from the stalk ; at d the stalks with their central bundle surrounded by a gap in the tissue; between them smallnbsp;transverse sections squeezed out of shape which belong either to intermediate leaves or to arrested seed-stalks; in thenbsp;periphery at c there are only such small transverse sections, which are here flattened; b represents the superficialnbsp;homogeneous layer of the cone, which is formed by the perfect coalescence of the extremities of the entire tuft ofnbsp;organs. The whole from preparations lying before me and made from material preserved in the Museum at Kew.

cates with the outside by means of a narrow canal and orifice^. In its base is the termination of the vascular bundle of one of the stalks whichnbsp;have cohered in the surface of the cone. Each of them therefore bears annbsp;ovule at its summit. If a section of a seed is made in the direction of itsnbsp;axis (Fig. 5 B), it is seen to have arisen from an atropous ovule; thenbsp;vascular bundle spreads at the base of the nucellus into a small disk-like

� Carruthers (4), t. 59, f. 6.

Expansion. The outer boundary of the nucellus can be seen in the form a stout line, and this is surrounded by the testa which was formed fromnbsp;^he integument. The testa coheres below with the surrounding tissues, andnbsp;'Contains a layer of shortly prismatic palisade-cells with a stout membranenbsp;^nd copious brown cell-contents. At the apex of the seed it runs out intonbsp;^ long exostome, which at first broad and inclosing a conical nucellarnbsp;process probably surrounding the pollen-chamber, ultimately narrows intonbsp;^ tube, and then after becoming a little broader terminates in the surfacenbsp;�f the cone. The behaviour of this integument is not represented bynbsp;*-arruthers, and is only to be observed in single seeds which have been cutnbsp;*^hrough with more than usual success. The figure in the text had tonbsp;obtained from several individuals. The same may be said of thenbsp;'^ell-contents. I have satisfied myself by searching examination of seedsnbsp;''t the British Museum which I have myself prepared, that inside thenbsp;�Membrane which is all that remains of the nucellus there is a normallynbsp;'iisposed embryo with two fleshy cotyledons lying flat on one another.nbsp;The embryo so entirely fills the space as to preclude the presence ofnbsp;endosperm. Carruthers� ^ figure gives an indication of this embryo.nbsp;The sketch in Fig. 5 shows somewhat diagrammatically the radicle, thenbsp;'^^getative point, the cotyledons, and their vascular leaf-traces which unitenbsp;*�0 form the vascular axis of the hypocotyledonary member. Such de-^'neations as these it is true are seldom met with, for most seeds are notnbsp;^'efficiently well preserved; but we can very commonly observe in trans-''erse or oblique sections the division between the cotyledons as a transversalnbsp;Assure passing through the inner mass of the seed.

The sketch here given of Bennettites, which I hope to make more '-Ornplete at some future time, is sufficient to show that its fructificationnbsp;'^sparts essentially from all that we are accustomed to find in the Cyca-; it is sharply and sufficiently characterised by its apparently axillarynbsp;'^��'gin, by the peculiar immersion of the seeds in the surface of the cone,nbsp;by the absence of endosperm. It is possible that the seed-stalks maynbsp;P''ove to be carpophylls of a peculiar kind; in that case we should benbsp;'Obliged to separate the Bennettiteae altogether from the Cycadeae, and tonbsp;'�^gard them as an intermediate group between Gymnosperms and Angio-^Perms. We should then have a typical case of that which Saporta andnbsp;ffirion ^ call proangiospermy, though we could not perhaps assume a directnbsp;quot;^^rivation of Angiosperms from this plant, and though it may have belongednbsp;*�0 a line of development which never reached our era. However this may

development of the female flowers from resting buds of the old stem cannot mislead us, for this circumstance, as is well known, recurs constantly asnbsp;a biological adaptation at very various points in the vegetable kingdom.nbsp;These conclusions enable us to dismiss Nathorst�s^ view, who, if I rightlynbsp;understand him in his paper, which unfortunately is only to be read in thenbsp;Swedish, compares Bennettites with the Balanophoreae, and especially withnbsp;Lophophytum, and considers it to be a parasite of the stem of a Cycad.nbsp;Saporta on the other hand, questions the facts of the case, and passesnbsp;over the genus with- the following words: � The following tribe, that ofnbsp;the Bennettiteae, is if possible still more strange, since according tonbsp;Mr. Carruthers it had enclosed fruits situated inside the enlarged basesnbsp;of the petioles. In spite of the apparent precision with which the detailsnbsp;of the anatomical structure are figured by the English botanist, it isnbsp;difficult to admit the reality of such organic combinations.� Renault � alsonbsp;seems to have been led astray by this and omits the genus altogether.nbsp;A fertile shoot petrified in carbonate of iron and probably belongingnbsp;to this group has been recently found in the Oxfordian beds of thenbsp;Vaches noires in Normandy by Moriere, and has been described bynbsp;Saporta and Marion^ as the fructification of Williamsonia Mori�rei, Sap.nbsp;et Mar.; its resemblance to the fructifications of Bennettites seems tonbsp;have escaped these writers.

Carruthers includes also in his genus a few other stems of similar elliptic form on the transverse section. First of all Bennettites Peachianus,nbsp;Carr.� from the Lower Oolite of Helmsdale in Sutherlandshire. The specimen in the Botanical Department of the British Museum, which is notnbsp;well preserved externally, shows the whorled transverse sections of thenbsp;lateral axes of the inflorescence, and must therefore belong to Bennettites-A small number of rings of secondary wood are developed in the pithnbsp;in a similar manner to that which will have to be noticed hereafter asnbsp;characteristic of the Medullosae. Bennettites maximus, Carr., of which nonbsp;figure is given, also belongs certainly to the group. I have satisfied myselfnbsp;of the presence of the lateral fertile shoots by examination of the originalnbsp;specimen in the Jermyn Street Museum in London. Both this species andnbsp;B. Saxbyanuscome from the Wealden formation of the Isle of Wight;nbsp;B. Saxbyanus also shows the lateral shoots, and its ring of wood is exactlynbsp;like that of B. Gibsonianus. In a specimen, which is classed by Carruthers ^nbsp;with the above forms and is split longitudinally, it can be seen that thenbsp;leaf-traces, of which numerous horseshoe-shaped transverse sections atenbsp;found in the outer rind, run direct and in straight lines in an obliquelynbsp;ascending direction from the ring of wood to the leaves. They do not

' Natliorst (5). nbsp;nbsp;nbsp;^ de Saporta (4), vol. ii, p. 53.nbsp;nbsp;nbsp;nbsp;^ Renault (2).nbsp;nbsp;nbsp;nbsp;* Saporta et Mario*'

(-2), p. 244, nbsp;nbsp;nbsp;quot; Carruthers (4), t. 62. Carruthers (4), t. 57.nbsp;nbsp;nbsp;nbsp;' Carruthers (4), t. 57, f- 4-

branch before they reach the leaf-stalks, and there is therefore no appearance of the leaf-trace-girdles which characterise our recent Cycadeae. How far this is true of all stems of Bennettites will have to be determined.

a series of forms which compose Carruthers� genus Mantellia, and which were named by Buckland Cycadoidea. The only differences adducednbsp;^re the lesser height, the globular or tuber-like shape, the circular outlinenbsp;of the transverse section, and the circumstance that the fertile shootsnbsp;project above the armour of scales and have only their basal portionsnbsp;preserved; the latter character however, even if it were of universalnbsp;occui-rence, which I doubt, cannot be looked upon as in any way essential.nbsp;To these forms belong the remarkable imperfectly silicified stems of lownbsp;growth, which have their upper extremity hollowed out by decay of thenbsp;tissue into the form of a bird�s nest, and in this state have been found innbsp;great numbers in the stone quarries of the Isle of Portland near Weymouth.nbsp;The Purbeck formation begins in this locality with marine limestonesnbsp;Which have supplied the material for many buildings in London ; thesenbsp;^re succeeded by a fresh-water or estuarine deposit, at the base of which

two carboniferous earthy layers about a foot in thickness and separated b'om one another, the so-called dirt-beds, with numerous prostrate ornbsp;Upright silicified stems rooted in them. Among these stems and in likenbsp;Position are found the Cycadeae which are called birds� nests by thenbsp;labourers, either singly or here and there in groups. For a further accountnbsp;uf the matter the reader is referred to Buckland and De la B�che^. Figuresnbsp;uf the different species distinguishable by the size and form of the scarsnbsp;loft by the detached scales are given by Carruthers^ (Bennettites Port-landicus, Carr., Mantellia nidiformis), by Schimper''^ (Cycadoidea megalo-Phylla, Buckl.), and by Buckland* (Cycadoidea megalophylla, Buck!., C.nbsp;^Icrophylla, Buckl.). The commonest species in the dirt-beds is said bynbsp;Authors to be C. microphylla; Buckland himself may have includednbsp;different forms in his C. megalophylla, for the figures show importantnbsp;differences. A fresh and connected examination of all these stems wouldnbsp;1^0 very desirable. To the same group also belongs a specimen named bynbsp;^U-rruthers� Mantellia inclusa, in which the fertile shoots have perishednbsp;^ud dropped out, leaving deep and broad holes in the envelope of scales.nbsp;�^Ud lastly, it seems to me probable from G�ppert�s� figures that his Rau-^uriae are really stems of Bennettites. I can positively affirm this ofnbsp;uurneria Schulziana, which was dug out of the ground in making a canalnbsp;**uar Gleiwitz during the last century, now that I have seen the original at

Breslau. Between the leaf-scars are seen broad spaces filled with the transverse sections of paleaceous scales; the whorls indicated in G�ppert�s^nbsp;figure belong to the fertile lateral shoots. Both characters are shown stillnbsp;more plainly in the figure of R. Reichenbachiana^, in the museum atnbsp;Dresden, which was discovered in the year i75.3nbsp;nbsp;nbsp;nbsp;^ bog at Lednice near

Wieliczka ; I also believe that I can recognise them in the photographic representation of R. Cocchiana�.

A small silicified stem has been found in the Rothliegende of Autun, but with its surface unfortunately not preserved, which according to Renault* shows a structure directly allied to that of livingnbsp;Cycadeae. This form, Cycadeoxylon Fremyi, has a pith of moderatenbsp;dimension surrounded by several rings of secondary growth (Renault'snbsp;figure� gives two complete rings and one half ring interposed betweennbsp;them). These rings exhibit the features which are characteri.stic of Cycadeae. The wedges of wood are very slightly developed, being usuallynbsp;only two cells in breadth, and appear in the tangential section as repeatedlynbsp;curved plates with enormously broad parenchymatous medullary rays runningnbsp;between them. The vascular bundles of the medullary sheath are no morenbsp;to be seen here than in living stems of Cycadeae; they were probablynbsp;destroyed at an early period by the great development of the medullarynbsp;rays. But while in living forms, which show repeated formation of cambium,nbsp;the successive secondary growths touch one another, they are separated innbsp;Cycadeoxylon by broad masses of parenchyma, which have been partlynbsp;destroyed; the portions of secondary cambium must therefore have beennbsp;formed in the middle of the cortical parenchyma and not on its innernbsp;margin. The tangential section of the rings of wood looks as if it hadnbsp;been taken from a stem of Cycas. The pits, which occur only on thenbsp;radial walls of the tracheides, are in alternate rows and are polygonal fromnbsp;mutual contact, and have exactly the appearance of Araucaroxylon. Anbsp;number of dark dots appear in the cortical parenchyma outside the outermost ring of secondary growth, and answer according to Renault to sonbsp;many gum-passages.

We have still to consider the Medullosae, a series of remains of stems from the Upper Coal-measures and the Rothliegende. The surface of thesenbsp;stems unfortunately is known only in a few cases, and in these only imperfectly ; but in their anatomical structure they show many points ofnbsp;resemblance to the Cycadeae, though they depart from them according tonbsp;the most recent investigations in some important particulars. I have beennbsp;able to satisfy myself from preparations that these differences have beennbsp;correctly observed. Good figures of sections of stems of Medullosa are to

Goppert (9), tt. 8, 9. nbsp;nbsp;nbsp;^ Camel (1).nbsp;nbsp;nbsp;nbsp;* Renault (1), vol. i-

be found in Cotta ^ first and next in G�ppert', and lastly and especially in the new memoir on the group by G�ppert and Stenzel� (Fig. 6).nbsp;In Medullosa stellata, Cotta, the oldest described species, we observe atnbsp;Ihe first glance a double peripheral secondary growth interrupted herenbsp;and there by broad medullary rays, and almost always forming the outernbsp;boundary of the specimens since the cortex is usually wanting. Thenbsp;broad pith is traversed by so-called star-figures, annular woody bodies ofnbsp;Small diameter and radial structure. If their transverse section is circular,

Ihey are termed by G�ppert and Stenzel star-rings (Fig. 6, C); if the section passes through the ovoid into an elongated linear form, they are knownnbsp;plate-rings (Fig. 6, �). If we examine these rings more closely, we findnbsp;that each of them answers to a normal secondary growth, which hasnbsp;developed its bast-layer on the outer, its woody layer on the inner side,nbsp;^be plates of wood are narrow, the medullary rays which lie between themnbsp;�^crease greatly in breadth towards the outside, and the alternation of thenbsp;causes the radial structure of the ring. The tissue in the centre ofnbsp;Ibe ring is unfortunately always destroyed, but in the case of the elongatednbsp;plate-rings there can be little doubt that, like the rest of the parenchymanbsp;the pith, it represents a partial pith in each ring. This may also havenbsp;the case with the star-rings. On the other hand, the star-rings may

have enclosed a medullary strand of vascular bundles, since I find in a section obtained from a specimen from Chemnitz two groups of vessels innbsp;the centre of the ring which have escaped the general destruction. Thisnbsp;point, as well as the question of the longitudinal course of these elements,nbsp;can only be cleared up by further researches, but we may have to waitnbsp;some time for these in the present scantness of material. It is greatly tonbsp;be regretted that the discovery of the silicified stems in the Rothliegendenbsp;of Chemnitz occurred so early in the last century, for the locality is nownbsp;nearly exhausted, and the most precious material has been frittered awaynbsp;and spoilt to make ornaments, and to furnish the mineralogical trifles innbsp;vogue at that time.

If we now examine the outer ring of wood in Medullosa stellata more closely, we become aware of the remarkable fact, first disclosed by G�ppertnbsp;and Stenzel, that the ring does not consist, as had long been supposed, ofnbsp;two consecutive annular secondary growths, as in Cycas, but that it isnbsp;composed of a variable number of plate-rings, which are narrow and morenbsp;or less elongated on the transverse section and together simulate a peripheral woody circle (Fig. 6, A). The intervals mentioned above andnbsp;formerly taken for broad medullary rays are simply gaps between thenbsp;single plate-rings of the circle of wood. The linear partial pith of thesenbsp;plate-rings appears on a superficial examination as the boundary of thenbsp;two consecutive secondary growths ; it is of course bounded by woodynbsp;tissue on its outer and on its inner side, and this is succeeded on bothnbsp;sides by normal bast-masses which are traversed by many transversenbsp;sections of fibre-cells. Disturbances, curvatures, and the like are quitenbsp;common in these plate-rings, as in those of the inner pith, and maynbsp;naturally be referred to the pressure to which the developing masses ofnbsp;secondary tissue were everywhere exposed in the middle of the body ofnbsp;the parenchyma. It might be supposed that there was another normalnbsp;woody cylinder outside the one which has just been described and whichnbsp;was formed of the plate-rings, and that we have therefore only thenbsp;pith of the stems before us. That this is not the case however isnbsp;proved by another species, M. Ludwigii, brought by Ludwig from thenbsp;Uralian Steppe and described by G�ppert and Stenzel. The surface, whichnbsp;is preserved in this stem, is covered with somewhat crowded roundishnbsp;impressions, which these authors unhesitatingly compare with the leaf-scarsnbsp;of the stems of Cycadeae. From the figure alone I can form no opinionnbsp;on the point; but the star-rings and plate-rings in this species are allnbsp;confusedly and irregularly disposed, and no peripheral woody cylinder isnbsp;formed from the plate-rings. All this seems to show, as G�ppert andnbsp;Stenzel very justly remark, that the anomalies in the growth of the stemnbsp;in Medullosae remind us much less of the conditions of growth in thenbsp;genera Cycas and Encephalartos than of those of Sapindaceae, and this is

brought out into the clearest light by a fossil form which we will now consider, Medullosa Leuckarti of G�ppert and Stenzel. The I'esemblancenbsp;between Medullosa and Cycas formerly brought into prominence and muchnbsp;insisted upon thus loses its importance, and if we nevertheless assumenbsp;n close relationship between this group and Cycadeae, this arises solelynbsp;from the great similarity in the character of the tissue in both. I wouldnbsp;add that we must enquire further whether the peripheral woody ring ofnbsp;some Bennettiteae, in which duplication is suspected, does not also ultimately show the conditions characteristic of Medullosae.

The form just mentioned, Medullosa Leuckarti, G�pp. and Stenz., is according to the figure a somewhat shapeless fragment of stem bearing thenbsp;stump of a thick lateral branch Its cross section shows only a few ringsnbsp;of secondary wood, some of which have the character of star-rings ; but thenbsp;greater part appear in the form distinguished by the authors as snake-rings.nbsp;These are marked by the great width of the partial pith, and also by thenbsp;extremely irregular shape of the flexuous ring which forms sinuses and projections. Wood and bast are in their normal position, and appear from thenbsp;figure to be well preserved; the latter tissue contains closed plates of fibre-eells. An allied form is Colpoxylon Aeduense, Ren., with respect to whichnbsp;G�ppert and Stenzel who were only acquainted with Renault�s figuresnbsp;�till express some doubt. I have seen in the Paris Museum several of thenbsp;beautiful plates prepared from the original specimens obtained at Autunnbsp;^nd one, a present probably from Brongniart to R. Brown, in the Botanicalnbsp;department of the British Museum, and have satisfied myself that in thisnbsp;species, just as in Medullosa Leuckarti, there is a variable number of broadnbsp;��regularly sinuous snake-rings, each of which encloses a parenchymatousnbsp;Partial pith. Myelopitys medullosa, Corda, from the Rothliegende of thenbsp;blorth of Bohemia, may also be nearly allied to the Medullosae; but thisnbsp;Question, owing to the small size of the fragment which Corda * had beforenbsp;film, can scarcely be perfectly cleared up even by a fresh examination of thenbsp;specimen.

Those who have paid any special attention to palaeophytology have long since remarked with surprise, that while remains of branches andnbsp;leaves of Conifers are comparatively rare and uncertain in their occurrencenbsp;in the Coal-measures, silicified w�oods of the type of Araucaroxylon are sonbsp;frequently met with in that formation. No one suspected at the time ofnbsp;the publication of Schimpers � Pal�ontologie V�g�tale� that these woodsnbsp;belonged to leaves which occur from the Devonian beds upwards, and arenbsp;found in the greatest abundance in the upper deposits of the Carboniferousnbsp;era, covering every surface of stratification with countless impressions.nbsp;These leaves, on account of their ribbon-like shape and parallel nervation,nbsp;were considered by most of the older authors, G�ppert especially \ to benbsp;Monocotyledons, and were named N�ggerathia or Cordaites. With themnbsp;were placed certain round, heart-shaped, or ovoid casts, also very abundant,nbsp;which were called Cardiocarpus, Rhabdocarpus, See., according to theirnbsp;form, and were usually compared with fruits of palms. Brongniart ^ alsonbsp;at first considered them to be Monocotyledons, but he soon gave up thisnbsp;view and put them and the casts of seeds just mentioned as a specialnbsp;family side by side with Cycadeae�, thus conjecturally recognising theirnbsp;real affinities. Goldenberg^ and Weiss� supported Brongniart on thenbsp;strength of important observations of their own, the latter indeed withnbsp;some hesitation and after having previously allowed the group to remain innbsp;its traditional position among the Monocotyledons. But opinion, foundednbsp;only on conjecture, still fluctuated with regard to the nature of thesenbsp;forms, till Grand� Eury� by his excellent investigations succeeded innbsp;clearing up the important points, and in establishing their claim to benbsp;reckoned among Gymnosperms. His results were extended and confirmednbsp;by Renault�s admirable examination of the inflorescences preserved in thenbsp;pebbles of Grand� Croix, to which Brongniart � assigned the detached seedsnbsp;occurring in the same material. It is entirely due to the efforts of thesenbsp;authors that the Cordaiteae, which a few years ago were among the most

' G�ppert (3) and (12). nbsp;nbsp;nbsp;Brongniart (4). Brongniart (5) and (2).nbsp;nbsp;nbsp;nbsp;* Goldenberg (2).

Weiss (1). nbsp;nbsp;nbsp;� Grand� Eury (1).nbsp;nbsp;nbsp;nbsp;^ Renault (1).nbsp;nbsp;nbsp;nbsp;* Brongniart (6).

doubtful of objects and were mixed up with N�ggerathiae, are now the best-known of all classes of fossil plants which are no longer included innbsp;our present vegetation.

The leaves of Cordaiteae are simple, sessile, elongate-elliptical or fibbon-like from a contracted base, and rounded or acute at the extremity. They are in all cases traversed by conspicuous parallel nervesnbsp;which lie very close to one another, and according to Grand� Eury are occasionally forked. Differences appear to have been observed in the size ofnbsp;the nerves, but we must be careful how we make use of this character,nbsp;since it depends a good deal on the mode of preservation. Usually allnbsp;the nerves are of the same size, or they gradually increase in size towardsnbsp;the middle of the leaf; more rarely stronger and weaker nerves alternatenbsp;regularly, as, for example, in Cordaites principalis. Gein., in which Grand�nbsp;Eury finds four weaker nerves between every two stronger nerves. Thisnbsp;observer has divided the entire group of Cordaiteae into three generanbsp;founded on the form of the leaves, but these must be regarded as entirelynbsp;provisional so long as their relation to the flowers which have been discovered is not better known than it is at present. These genera are Dory-cordaites, with leaves which may be fifty centimetres in length and whichnbsp;narrow gradually into an acute apex ; Poacordaites, in which also the leavesnbsp;niay be half a metre in length; but are linear and grass-like and are suddenlynbsp;bounded off to an obtuse termination ; and Cordaites, with shorter obovatenbsp;nc spathulate obtuse leaves which are sometimes incised. The Poacordaitae,nbsp;'''hich are chiefly found at St. Etienne in different beds from the other twonbsp;types, have been recently separated from them by Renault ^ and placednbsp;''�ith Taxineae. I am not informed respecting the reasons which havenbsp;determined him in this matter.

Leaves of Cordaites are extraordinarily abundant in the black pebbles Grand� Croix. In some fragments, such as one for which I am indebtednbsp;*�0 Renault�s kindness, large numbers of the leaves lie in layers one abovenbsp;Another like damp beech-leaves on the ground in our forests. In thesenbsp;specimens the structure is often well preserved, and the distribution of thenbsp;f'ssues displays a surprising multiplicity of detail considering the uniformitynbsp;shape. Unfortunately the silicified leaves come under our observation in

j^gments only, and it is impossible to refer them with any certainty to the different species which have been determined from the impressions. Renaultnbsp;therefore marked all the transverse sections which he has named withnbsp;^ note of interrogation; and Grand� Eury has given special specifle namesnbsp;unded solely on the anatomical structure to the forms which he has ex-nrruned. All the leaves which have been carefully studied, with the exceptionnbsp;one kind only, show a simple layer of parallel vascular bundles running in

the middle of the substance of the leaf; in Cordaites duplicinervis, Grand� Eury, the bundles approach nearer first to the upper and then to the undernbsp;side, being in the former case smallei', in the latter larger on the transversenbsp;section. Each bundle together with the adjacent parenchyma, which isnbsp;often obliterated, is usually surrounded by a firm sheath formed as a rulenbsp;of a single cell-layer. The bast-portion has in most cases disappeared, andnbsp;the position of the gap thus produced enables us to determine the undernbsp;side of the leaf with tolerable certainty. The woody portion of the bundle,

on the other hand, is marked by a peculiarity,nbsp;which in our modernnbsp;vegetation is found onlynbsp;in the leaves of Cycadeaenbsp;and in those of Iso�tesnbsp;and Ophioglossum. Itsnbsp;initial group (Fig. 7, c)nbsp;lies on the bast-side ofnbsp;the bundle, either closenbsp;to the gap or boundednbsp;on the side of the gapnbsp;in several species, according to Renault, bynbsp;a group of one or morenbsp;rows of tracheides whichnbsp;have a curved transversenbsp;section (Fig. 7, b). Innbsp;the latter case we should

have exactly the structure of the leaf-stalk of Cycadeae. Inside of the initial group is a stronger and outside of it a weaker mass of wood, and thenbsp;development of both appears from the accotmts given of it to advance, asnbsp;in Cycadeae, in both directions from the initial group. Both here, and innbsp;Cycadeae and elsewhere also, Renault terms the inner portion of the primarynbsp;woody bundle the centripetal xylem (bois centrip�te), the outer the centrifugal xylem (bois centrifuge); he speaks of the whole bundle as thenbsp;diploxylous bundle (faisceau diploxyl�), to distinguish it from the normalnbsp;bundle, the monoxylous bundle (faisceau monoxyle). In treating of thenbsp;Sigillarieae we shall have further to consider how far this terminology isnbsp;justifiable, and above all how far it answers its purpose. If, as accordingnbsp;to Renault appears to be the case in other leaves of Cordaitae, the outernbsp;portion of the primary wood (the centrifugal xylem) is wanting, we have thenbsp;structui'e which we find in the vascular bundle of Iso�tes. Schenk ^ in his

account of Renault�s statements has not given them correctly, inasmuch as in the explanation of the figures he terms the outer strand of the primarynbsp;'vood the � phloem,� and must therefore suppose that the elements in question are fibre-cells of the bast. But I have satisfied myself by examinationnbsp;of Renault�s � original preparations that his account of the matter is perfectlynbsp;Correct. With regard to the rest of the leaf-tissue, the epidermis on bothnbsp;sides of the leaf is formed of cells bounded by straight lines and approximately rectangular; on the under side are rows of stomata lying parallel tonbsp;the surface of the leaf, but there are none on the upper. In some forms thenbsp;cells of the upper side are developed into pointed papillose processes, as innbsp;Cordaites tenuistriatus The parenchyma of the leaf may be uniform s, butnbsp;it is usually differentiated into three layers, a loose irregular tissue on thenbsp;tinder side, a tissue more or less distinctly resembling palisade-tissue on thenbsp;tipper side, and an intermediate � transfusion-tissue � occupying the spacenbsp;between the bundles; this middle tissue is lacunose in character with broadnbsp;intercellular spaces, and is formed of cells lying across the leaf. There arenbsp;nlso the mechanical elements in a variety of forms. Where these are slightlynbsp;tieveloped and the entire parenchyma of the leaf is also uniform (C. crassus^),nbsp;Bley appear as single sub-epidermal fibres answering to the vascularnbsp;bundles on both sides of the leaf, but not reaching as far as the bundle-sheath. Besides these there is on the under side between every two bundlesnbsp;^ narrow much-projecting strand of fibres, which has nothing to correspondnbsp;i-u it on the upper side. In other forms the fibre-strands unite from abovenbsp;^nd below with the sheath of the vascular bundles, forming the well-knownnbsp;'^nstomary longitudinal trabeculae. Lastly, in C. angulostriatus (Fig. 7, f)nbsp;*^hese are connected together on both sides by a continuous sub-epidermalnbsp;^^yer of fibres, which swells up into one or more rib-like projections betweennbsp;'�he bundles, and this perhaps explains the appearance in the impressionsnbsp;the fine intermediate nerves peculiar to some Cordaitae. There mustnbsp;^�^rtainly be a connection between the greater or lesser degree of prominencenbsp;the nervation in the impressions of the leaves, and the fact that in somenbsp;l^urtns the thin leaf-surface over the nerves appears thickened into a knotnbsp;the transverse section, while in others nothing of the kind can be ob-^^rved. That with all this the structure of the leaves is essentially resistantnbsp;has been already remarked by Schenk�; we see by this case the greatnbsp;^(itiquity of these anatomical phenomena of adaptation to external con-bitions; we shall find them reappearing on different occasions as wenbsp;P^'oceed with our subject, and we may conclude on the whole that thosenbsp;^^ternal conditions, which we see determine this adaptation at the presentnbsp;prevailed as early as the period of the Coal-measures.

Branches of Cordaiteae stripped of their leaves are frequency found at St. �tienne in the beds which are filled with leaves. Specimens withnbsp;these leaves still attached to them are however rare. Little attention seem-snbsp;to have been paid to them in other places. They occur as impressions ornbsp;flattened casts covered with a rind of glistening coal, and with the leaf-scarsnbsp;in some cases still apparent on their surface. Numerous specimens of suchnbsp;portions of branches have been figured by Grand� Eury�. These scars,nbsp;in correspondence with the contraction of the bases of the leaves, arenbsp;elliptical on the transverse section and of no great breadth, and where thenbsp;preservation is particularly good, they show a transverse row of dot-likenbsp;vascular bundle-traces. They are placed, as in our pines, on the summitnbsp;of semicylindrical leaf-cushions which are decurrent on the branch, andnbsp;which flatten out more or less quickly and disappear. That the branchesnbsp;really belong to Cordaites is proved by some drawings of Grand� Eury, innbsp;which they are still covered with the leaves and even bear inflorescences.nbsp;Some care is required in judging of these figures, for the author often givesnbsp;us reconstructions which he does not always distinguish quite clearly fromnbsp;the portions drawn from nature. For this reason I can only cite one figurenbsp;as decisive, that of C. alloidius^. Grand� Eury, which is described at lengthnbsp;and satisfactorily in the text. In the lower part of this leafy branchlet thenbsp;scars are crowded close to one another, giving to the surface the appearancenbsp;of Lepidodendron ; in the upper part they are widely separated throughnbsp;the elongation of the internodes. Apart from Grand� Eury�s drawings, thenbsp;tufts of leaves of Cordaites and the branches which bear them are verynbsp;sparingly figured in the literature. The oldest figure is the one in Sternberg�s work^ which however only shows a number of leaves convergingnbsp;downwards with their bases broken off. It is the figure of Flabellarianbsp;borassifolia, and is taken from a specimen found at Radnitz in Bohemia-Germar'¹ next describes the upper extremity of a branch thickly coverednbsp;with leaves as Flabellaria principalis. Then Corda� figures a splendidnbsp;leafy branch under the name of Flabellaria borassifolia, Stbg; the anatomicalnbsp;drawings in the next plate can hardly belong to this species. G�ppert¹�nbsp;gives an account of a very leafy branch named N�ggerathia palmaeformis,nbsp;G�pp. All these figures are to be referred to the type Cordaites of Grand�nbsp;Eury ; on the other hand, the fine specimen from the Goldberg collection,nbsp;figured by Weiss ^ and named Coi'daites microstachys, Weiss, belongs tonbsp;Poacordaites, and is considered by Grand� Eury to be his P. linearis-Some at least of the many beautiful branches figured by Lesquereux� maynbsp;belong to this type. Closed leaf-buds also have been found at St. �tienne

Grand� Eury (1), tt. 27, 28. nbsp;nbsp;nbsp;^ Grand� Eury (1), t. 21, f. 8.nbsp;nbsp;nbsp;nbsp;= Sternberg, Graf von (1)gt;

Heft 1-5, t. 18. nbsp;nbsp;nbsp;¹ Germar (1), t. 23, f. 5.nbsp;nbsp;nbsp;nbsp;¹ Corda (1), tt. 24, 25.nbsp;nbsp;nbsp;nbsp;� G�ppert (12), t. i5'

both in impressions and in the pebbles ; the leaves in these buds show the convolute aestivation, such as may be seen in the beautiful drawing of anbsp;transverse section given by Renault^. Where the inner structure can benbsp;determined in branches evidently belonging to Cordaitae, the structure of thenbsp;Wood is seen in all cases to be that of Araucaroxylon. We find too thatnbsp;the wood has exactly the same character in the portions of branches whichnbsp;are preserved in the pebbles of Grand� Croix, and which are remarkable fornbsp;the unusual breadth of the cylinder of pith. The tissue of the pith usuallynbsp;disappears at an early period, persisting only in thin transverse diaphragm-plates which show greater solidity, just as happens for example at thenbsp;present day in branches of the walnut-tree. In consequence of thisnbsp;peculiar behaviour the branches of true Cordaitae are sharply differentiatednbsp;from other trees with a similar woody structure. Hence also Araucaroxylonnbsp;cnedullosum, Kr. (Pitus primaeva, With.), must certainly be placed in thenbsp;present group; the broad transversely segmented pith is surrounded bynbsp;primary bundle-strands, which, as in Araucaroxylon, are separated bynbsp;tnany medullary rays. The cortex, where its structure is preserved, isnbsp;Wiarked by few special features ; its uniform parenchyma encloses a rathernbsp;large number of fibre-strands, and also shows here and there isolatednbsp;Irirnina filled with a dark substance, receptacles of resin or gum, as Renault^nbsp;'Considers. Beautiful figures illustrating the anatomy of Cordaites will benbsp;found in this author

Peculiar casts of stems, to which Sternberg gave the name of Artisiae**, l^ave long been known to occur not unfrequently on the refuse-heaps ofnbsp;Ooal-mines. These are cylindrical in shape but are usually flattened bynbsp;Pressure, and are divided by deep transverse annular furrows into numerousnbsp;fhiri lamelliform segments which lie one on another like pieces of money innbsp;^ roll. They separate very readily from one another at the partitions.nbsp;Williamson� was the first to perceive that these casts fill the medullarynbsp;^^vities of stems and branches with the structure of Araucaroxylon. Therenbsp;no longer any doubt on this point, since Grand� Eury� has shown thatnbsp;fhey occur inside undoubted branches of Cordaites, and Williamson'^ andnbsp;^nnault � have pointed out in the petrified axile portions the particularnbsp;^fructure of the pith on which their form is based. The constrictions there-fore in these casts answer to the persistent margins of the diaphragms ofnbsp;Pflh, which were broken through in the process of decay or were otherwisenbsp;Pnrtially destroyed before infiltration. The surface of the stems is usuallynbsp;^'�iooth, but angular forms and forms marked with transverse circles alsonbsp;�ccur, like those for example figured by Grand� Eury It is a questionnbsp;quot;hether we may not be dealing in these cases with casts of the medullary

5, nbsp;nbsp;nbsp;(1)) t-16, f. :.nbsp;nbsp;nbsp;nbsp;� Renault (1).nbsp;nbsp;nbsp;nbsp;� Renault (1), t. 15. � Sternberg, Graf von (1), Heft i-,5, t.

^ illiamson (4), ^ Grand�Eury (1). Williamson (1), ix. � Renault (1). ^ Grand Eury (1), t. 28.

cylinder of other kinds of plants, and this seems to find support in Corda�s ^ belief that he has observed Artisiae occupying the centre of the stem ofnbsp;his Lomatofloios crassicaulis, which certainly belongs to Lepidodendreae;nbsp;at the same time, when we examine the figure of the stem in question wenbsp;cannot help doubting whether it really belongs to Lomatofloios. Thesenbsp;same Artisiae in conjunction with Araucaroxylon have rightly determinednbsp;Grand� Eury ^ to claim the numerous cylindrical main stems of trees foundnbsp;in the quarries in the neighbourhood of St. �tienne, in an upright positionnbsp;and still rooted in the ground, as belonging to Cordaitae. The fragments ofnbsp;roots with the normal structure of Coniferae, discovered by Renault ^ in thenbsp;pebbles of Grand� Croix, must also no doubt be referred to the same group.

Before proceeding to consider the structure of the flowers and seeds of Cordaitae, it will be advisable to say a few words respecting the distributionnbsp;of the leaves and stems of these plants in the different formations. Therenbsp;can be no doubt of their existence in the Devonian beds ; beautiful leaves ofnbsp;Cordaites Robbii are figured by Dawson � from Canada; the same authornbsp;states that he has found Artisiae inside petrified stems of his Dadoxylonnbsp;(Araucaroxylon) Ouandongianum � from the Middle Devonian. Thenbsp;Cordaitae are found throughout the Coal-measures, being extremelynbsp;common in the uppermost beds of the formation, and are still abundant innbsp;the Rothliegende.

Whether the type of Cordaiteae was continued into the later formations, and for what length of time, we are unable to say. Leaves of similar character to those of Cordaiteae are found as high up as the Tertiaries, asnbsp;may be seen by referring to Feildenia which is discussed with Taxineae.nbsp;Among these doubtful forms must be reckoned a genus described by O.nbsp;FeistmanteD as N�ggerathiopsis and confined to India and Australia. Innbsp;this genus we may place a form first introduced to notice by Dana * undernbsp;the name of Noggerathia prisca from a deposit known as the Newcastlenbsp;beds, in which the character of the fauna is said to be Palaeozoic and that ofnbsp;the flora Mesozoic, and which according to O. Feistmantel is one of the lowestnbsp;beds of the Trias. Another form, Noggerathia Hislopi, Feistm., occurs innbsp;the Lower Gondwanas of India, which are said to be the equivalent ofnbsp;the European Trias. Noggerathia obovata, Carr.�, from the coal fields ofnbsp;Southern Brazil, should perhaps be placed in the same genus. The leaves ofnbsp;N�ggerathiopsis greatly resemble those of Cordaitae with short broad leaves.nbsp;O. Feistmantel distinguishes sharply betw'een the two genera, apparentlynbsp;on account of the bifurcation of the nerves in N�ggerathiopsis, but thisnbsp;according to Grand� Eury is not unknown in Cordaites. Feistmantel con-

' Corda (1). nbsp;nbsp;nbsp;� Corda (1), t. 5, f. 2.nbsp;nbsp;nbsp;nbsp;* Grand� Eury (1), tt. 29, 34.nbsp;nbsp;nbsp;nbsp;� Renault (1), t. i5-

^ Dawson (1), t. 14, f. 156. nbsp;nbsp;nbsp;� Dawson (1), t. 21.nbsp;nbsp;nbsp;nbsp;'' O. Feistmantel (1), and Pal. Ind., ser. xii-

siders these leaves of N�ggerathiopsis to be single detached leaves of Cycadeae^ but I am unable to find in his account of them any good groundnbsp;for this view. He compares them with Macropterygium Bronnii, Rhipto-zamites, Schmalh., and some remains described as Podozamitae ; but allnbsp;these forms, as has been already stated, are of very doubtful character.nbsp;Details respecting N�ggerathiopsis will be found in his extensive publications, in which he has also, collected the literature of the plant-bearingnbsp;deposits of India, Australia, and South Africa.

We may notice also in this place the genus Yuccites^, which contains a number of fossil remains from Triassic and Jurassic deposits. Schimpernbsp;himself says of it: � It is needless to say that these fossils may come fromnbsp;types which are very different from one another, and which may have nonbsp;real analogy with the living type with which we compare them.� Schimpernbsp;Says that the rush-like leaves of these Yuccitae have an appendage whichnbsp;embraces the stem, and this may be the only character which wouldnbsp;certainly separate them from Cordaitae ; but it appears to me to be premature to place them at once for this reason among Proangiosperms, asnbsp;done by Saporta and Marion

If we find ourselves on the whole in a position to pick out the Palaeozoic Coi'daitae from out of this chaos of remains marked bynbsp;parallel nerves and by similarity of habit, and to determine them at leastnbsp;m the most general features of their organisation, we owe it, as I take everynbsp;opportunity of saying, solely to the exact knowledge of the flowers of anbsp;lew species which we have gained through the labours of Renault. I willnbsp;^dd at once that I am far from thinking that the common connection ofnbsp;^11 these forms of Cordaitae is thus certainly established. Still the followingnbsp;mmarks will suggest some grounds for the view that this type represents anbsp;l^rge and much differentiated group of plants, which must be coordinatednbsp;quot;'ith Coniferae or Cycadeae, though we can at present discern its realnbsp;Mature only from the characteristic marks of single selected species. Wenbsp;have therefore as yet no means of judging of the degree of differen-1'ation of the characters in the group. If there were no Conifers at presentnbsp;m existence, and we were compelled to picture their organisation to ourselvesnbsp;horn the flowers, suppose of Ginkgo only and Callitris, with some help fromnbsp;leafy branches, our condition with regard to them would in my opinion benbsp;'dearly th^t in which we find ourselves at present in dealing with Cordaiteae.

In the siliceous fragments of Grand� Croix we find now and again �mall buds composed of leaves lying close one upon another, and representing male and female inflorescences (Figs. 8, 9). That these are flowersnbsp;Cordaitae has been directly proved by the character of the leaves in

a female specimen, with which all the rest agree perfectly in the structure of the ovule; and that the male flowers really belong to these femalenbsp;flowers may be shown by means of the highly characteristic pollen-grainsnbsp;(Figs. 8 dquot;, 9 C), which Renault ^ has discovered both in loco natali, in thenbsp;loculaments of the anther, and in their place of destination, the apex ofnbsp;the nucellus of the ovule, and with the same characteristic appearance innbsp;both positions. Renault has figured three .different male flowers, and

described them as Cordaianthus Penjoni, C. subglomeratus, and C. Sapor-tanus. These are the commonest species, the other and rarer kinds have yet to be published. The flower-bud of C. Penjoni consists of a tolerablynbsp;thick axis closely enveloped in small narrow one-nerved spirally disposednbsp;leaves. The summit of the axis is occupied by one or two male flowers,nbsp;and similar flowers, as is well shown in the transverse section are foundnbsp;scattered about among the leaves, and appear in this case to be placed iiinbsp;the leaf-axils. The individual flower, which is borne on a long cylindrical

Stalk, is perfectly naked, and consists of a few linear elongated cylindrical sessile erect pollen-sacs, which are attached by their base and form a tuft by their divergence. Judging by the figures of the transverse section,nbsp;(Fig. 8, A) the pollen-sacs are usually five or six in number. Their wallsnbsp;are formed of a palisade-like cell-layer, and open by a longitudinal fissurenbsp;placed on the side towards the tuft and extending down the whole lengthnbsp;of the sac. What is here spoken of as the flower is termed by Renault thenbsp;stamen ; this author speaks of the flower as follows : � These flowers arenbsp;extremely simple, being formed of a few stamens only, which are eithernbsp;scattered about in groups of two or three, or appear singly in the middle ofnbsp;the sterile bracts.� It is just the latter circumstance, namely that the flowersnbsp;in the axils of the leaves are always reduced to a stamen of this kind, whichnbsp;leads me to regard each of these organs as a simple flower, and the partnbsp;that bears it as a flower-stalk, not as a filament. That they are groupednbsp;together at the summit admits also of an easy explanation; the growth ofnbsp;the bracts may have been ari'ested at this spot. And all the flowers, ifnbsp;understood in this way, are alike in character, whereas according tonbsp;Renault�s view their mode of development is different in different partsnbsp;of the inflorescence. Lastly, the view here taken is supported by the circumstance, that all the organs which are collected together at the apexnbsp;of the shoot, while differing from one another in length and age, arenbsp;arranged according to the requirements of acropetal order of de-'�clopment

The pollen-grains (Fig. 8, C) are found in the loculaments, and occur also scattered about in great abundance in the siliceous fragments. Theynbsp;are ovately elliptical, their dimensions according to Renault being 0 9 andnbsp;�'5 of a millimetre. They are as a rule well preserved, evidently owingnbsp;lo the cuticularisation of their outer membrane, and their surface is orna-�Uented with a fine shagreen-like reticulation. Within and adjoining thenbsp;Cell-wall on one side is the cell-group characteristic of Gymnosperms,nbsp;^hich shows a remarkably high degree of development, and consists of annbsp;'lUusual number of thick-walled irregularly polygonal cells united togethernbsp;*^to a tissue.

Quite similar conditions are observed also in the two other species described by Renault, in which however the flowers are all crowded together at the summit of the shoot, there being none that are axillary andnbsp;Peripfierap Cordaianthus Saportanus moreover has a very short flower-^lalk^, and in C. subglomeratus the buds of the inflorescence are crowdednbsp;*-�gether in clusters �. The figures also given by Grand� Fury may belongnbsp;this or to a similar species

CORDAITEAE.

Fig, 9. P'emale flowers of Cordaiteae, after Renault A tangential section of the inflorescence of Cordaianthus Williamsoni, Ren. B transverse section of the flowering shoot of Cordaianthus Zeilleri, Ren. C median longitudinalnbsp;section of the ovule of Cordaianthus Grand� Euryi, Ren., with a portion of the integument and nucellus, in whichnbsp;is nothing to be seen as yet of the embryo-sac; beneath the beak-like process is the pollen-chamber, and in thenbsp;chamber, and in the tube which passes through the beak and gives access to the chamber, are a few pollen-grains-D the beak-like process of the nucellus of the preceding figure more highly magnified; wedged in it are the larg�nbsp;pollen-grains with shagreened exinium and internal cell-formation.

^ Renault (1).

Four species of female Cordaianthus are described by Renault, Cor-daianthus Williamsoni, C. Grand� Euryi, C. Lacattii, and C. Zeilleri. But we must combine their characters to form a general idea of thenbsp;group, because we have only longitudinal sections of the first three speciesnbsp;and only a transverse section of the last (Fig. 9, E). The figure of thenbsp;fourth species ^ shows us a shoot exactly resembling the male shoot, andnbsp;surrounded by crowded spirally disposed leaves ; four flowers in the axilsnbsp;of leaves are cut through in the upper portion of the shoot, and the apexnbsp;is prolonged beyond the flowers and bears a tuft of stunted leaves deformednbsp;through pressure. The longitudinal sections (Fig. 9, A)quot;^ are all madenbsp;obliquely to the axis, and therefore the longitudinal sections which theynbsp;afford of the axillary flowers are sometimes more, sometimes less, exactnbsp;in their direction. In Cordaianthus Williamsoni (Fig. 9, A) the apical tuftnbsp;of leaves above these flowers is shown in the surface view, and the leavesnbsp;have the habit of those of Cordaites. Renault states � that the femalenbsp;flowers of all the Cordaitae which he has examined give off small secondarynbsp;shoots, which arise in the axil of the leaf and are provided with a pair ofnbsp;bracteoles. The number of the leaves in the tuft is said to vary. Thisnbsp;appears in the figures only in the case of Cordaianthus Williamsoni, wherenbsp;the axillary shoot lies in the exactly median plane of section, and as thenbsp;short leaf exposed by it is in front (Fig. 9, A), one or two lateral leavesnbsp;aiust have preceded it. As the axis of the inflorescence-bud is remarkablenbsp;for its unusual thickness, the axis of the flower-bearing axillary buds is alsonbsp;proportionally thick. The flower, which is evidently dead and on the pointnbsp;of falling off, is attached to the axis by a broad base, and begins withnbsp;^ stout envelope like an integument, which contracts into a narrow canalnbsp;below and becomes wider and funnel-shaped above. The floral axis enclosednbsp;the envelope rises in form of a thin stalk, and on the top of the stalk isnbsp;fbe shrivelled nucellus surrounded by a broader integument, which is firmlynbsp;attached to the inside of the outer envelope. The nucellus, which hasnbsp;^ peculiarly shaped conical termination, is shrivelled and stunted; in C.nbsp;Lacattii ^ in which it has a similar form but is better preserved, it fillsnbsp;fbe whole of the space enclosed by the integument, and this was probablynbsp;'�^e case in the other form also. In the transverse section of the inflorescence of C. Zeilleri only the thick outer envelope of the flowernbsp;bas been preserved. The details of the structure of the nucellus have beennbsp;^udied by Renault from , his preparation of C. Grand� Euryi (Fig. 9, C) �.

be bud contained two axillary flowers, one of which must have been destroyed in making the section. The prolongation of the axis describednbsp;^bove between the outer and inner envelopes is not shown. The nucellus

is ovoid in form, and its rounded apex rises suddenly into a slender beaR-like process, which encloses a narrow canal and has its wall formed of a single layer of large transversely broadened cells. In the apex of thenbsp;nucellus exactly under the process the canal enlarges into an irregularlynbsp;rounded cavity, the pollen-chamber as it has been termed, the � chambrenbsp;pollinique� of the French author. In this chamber several pollen-grainsnbsp;are to be seen, which exhibit the structural peculiarities known to us fromnbsp;the male flower. In the conducting canal also there are two grains innbsp;excellent preservation lying one above the other and quite filling its lumennbsp;(Fig. 9, D) k Of the embryo-sac and its contents there is nothing to benbsp;seen. Renault has already pointed out that the flowers of Cordaitae mustnbsp;have been anemophilous; for unless they secreted a pollen-catchingnbsp;drop after the manner of Taxus, it would be impossible to imaginenbsp;how the pollen-grains, which are unusually large in proportion to thenbsp;breadth of the micropyle, could have found their way into the pollen-chamber. I would observe also, that it would almost seem from thenbsp;figures that the great increase in the transverse breadth of the parietal cellsnbsp;in the base of the beak was intended to diminish the size of the canal, andnbsp;so prevent the entrance of too many pollen-grains into the pollen-chamber,�nbsp;an arrangement analogous with the closing of the canal of the archegoniumnbsp;in many Archegoniatae after the period of reception is over.

With regard to the terminology of the envelopes of the female flower, it is evident that we must set out from the principles adopted in the casenbsp;of Gnetaceae, and especially in that of Ephedra; the inner envelope mustnbsp;in all cases be considered to be an integument, while the outer may benbsp;regarded either as the perigone, or as a second integument, according asnbsp;we assent to the determinations of Eichler or of Strasburger, or even as thenbsp;ovary for which Renault inclines to take it in accordance with Vannbsp;Tieghem�s views. The male flowers it is true are less like the male flowers ofnbsp;Gnetaceae, though Saporta and Marion ^ have compared them with thosenbsp;of Gnetum. Lastly, before turning to the consideration of the ripe seedsnbsp;it will be necessary to notice a view which Renault � has formulated in thenbsp;following words : � It appears then that the pollen-grains were not yet in anbsp;condition, when they left the anther, to produce fertilisation, and that theynbsp;required to remain for a longer or shorter time inside the pollen-chamber,nbsp;where the cellular division commenced in the anther was completed andnbsp;resulted in the maturity of the grain.� As Saporta and Marion ^ havenbsp;taken up this idea and applied it to their own speculative purposes, wenbsp;must briefly consider the foundations on which it rests. It is pointednbsp;out that if the pollen-grains from the anthers are compared with those

in the pollen-chamber, a great and striking difference in size is at once perceived; the latter may be as much as a third larger than the others.nbsp;Again, the cell-mass formed inside the grain, which was much smaller thannbsp;the inner space of the grain in the anther, quite fills that space in thenbsp;grains found in the chamber and its cells have increased in number. Ifnbsp;this is indeed the general rule, the assumption of a subsequent furthernbsp;development of the kind described above can scarcely be avoided. Thenbsp;objection, that the pollen in the chamber is different from the pollen in thenbsp;anther, the two organs having belonged to two different species, wouldnbsp;explain the difference in size but leaves us still in a difficulty; for in thatnbsp;case we should expect to meet with the pollen of the chamber also lyingnbsp;freely about in the pebbles, which does not appear to be the case. But nownbsp;that we know that the pollen-tube in recent Gymnosperms does not proceednbsp;from the internal cell-mass, the comparison of the process of developmentnbsp;in the two cases must at present be regarded as altogether obscure andnbsp;doubtful.

It has already been incidentally remarked that casts of very various form, named carpoliths, are objects of common occurrence in the Coal-measures. These fossils would however be perfectly worthless from thenbsp;botanical point of view, if they were not also found in a silicified state innbsp;fhe pebbles of Grand� Croix and in the carbonaceous nodules in seams ofnbsp;Coal. For that in all these cases we are dealing with the same remainsnbsp;must be evident from their identity of form and from their mutual association, especially when it is considered that the materials which have comenbsp;down to us, sometimes in the form of coal, sometimes as impressionsnbsp;between slates, sometimes in a silicified or calcified condition, are all alikenbsp;'vegetable remains from ground once covered by forests. We are indebtednbsp;for searching investigation into the remains of fructifications represented bynbsp;tbe carpoliths to Hooker and Binneyi, and Williamson^, and above all tonbsp;tbe prolonged researches of A. Brongniart Now that all the various seedsnbsp;quot;'hich have been examined have proved without exception to be seeds ofnbsp;^gymnosperms, we may with great probability assume that all carpolithsnbsp;from the Coal-measures are remains of Gymnosperms. But since thenbsp;^ordaiteae are now acknowledged to be a highly differentiated division ofnbsp;fbe series of Gymnosperms, it is equally probable that many of the carpo-which are found moreover in the same deposits with Cordaiteae, are

remains of these plants. Impressions of carpoliths have in several cases found in connection with those of leafy branches, but this point will benbsp;Noticed again at greater length at the end of this chapter. Other carpolithsnbsp;^S^in may be seeds of Conifers or Cycads, or may even prove to belong to

' Hooker and Binney (1). nbsp;nbsp;nbsp;* Williamson (1), viii. � Brongniart (6).

Gnetaceae or to some other groups of Gymnosperms not yet sufficiently recognised and defined. But since it is not possible at present to distinguishnbsp;these remains according to their origin, we must be content here with somenbsp;general remarks upon the whole group.

All the seeds studied by Brongniart were formed from orthotropous ovules, and, as has been already said, are of essentially the same structure,nbsp;whatever difference there may be in details. They are inclosed in a well-preserved and often very thick testa, which is in some cases homogeneousnbsp;and lignified, but in many others has an outer fleshily succulent layer likenbsp;that in the seeds of Ginkgo. The happily chosen terms sarcotesta andnbsp;endotesta have been applied to the two layers. Where the testa appears tonbsp;be formed of one layer only, it is not indeed always certain that there wasnbsp;not originally a sarcotesta which was destroyed before petrifaction ; even innbsp;the casts known as Rhabdocarpus traces of impressions have occasionallynbsp;been seen, which suggest the former existence of such a layer k From ripenbsp;seeds not well preserved in all their parts it is obvious that we cannotnbsp;always be sure of the number of the integuments in the ovule. The nucellusnbsp;lies in almost all cases immediately inside the testa; Pachytesta, Brongn.,nbsp;is the only species in which the apex of the nucellus is enveloped in anbsp;distinctly discernible innermost integument In other forms such differentiations, though they may possibly have been in existence at the periodnbsp;of flowering, can no longer be perceived. In many cases the nucellus isnbsp;quite destroyed, or its outer boundary only is preserved in the form of anbsp;fine line; in its place there is usually a cavity, the wall of which is linednbsp;with crystals of quartz. In the best state of preservation the tissue of thenbsp;nucellus has disappeared up to the outermost boundary line, but the embryo-sac with the endosperm inclosed in it is plainly seen. The egg-cells appearnbsp;in the convexity of the upper end of the endosperm, separated by somenbsp;distance from each other, as is usual in Cycadeae, and generally distinguishednbsp;by their shrunken brown contents. Cardiocarpus sclerotesta, C. augustodu-nensis and Taxospermum Gruneri supply good examples of these phenomenanbsp;(Fig. jo). The structure of the apex of the nucellus is highly characteristicnbsp;in all the forms ; its tissue seems to have possessed greater power ofnbsp;resistance, and is seen usually in a good state of preservation on the top ofnbsp;the bounding line which indicates the nucellus. It forms a conical projection,nbsp;and is pierced by a canal which widens below into a pollen-chamber in somenbsp;cases (Stephanospermum akenioides. Fig. lo, A c) of considerable dimensions,nbsp;and usually containing numerous pollen-grains. The structure agreesnbsp;thoroughly in all these points with that of the female flowers of Cordaiteaenbsp;described above. The course of the vascular bundle in the seeds followsnbsp;closely that which is customary in Cycadeae. The single bundle ter-

minates in the base of the nucellus, where its elements spread out in a radiating manner, but it previously gives off lateral branches, usually two innbsp;number, which traverse the testa till they nearly reach the micropyle. Itnbsp;may seem strange that the egg-cells have been observed in the substance ofnbsp;the endosperm, but not a developed embryo, though this has been seen innbsp;Bennettites. The probable explanation is, that in these forms the development of the embryo proceeds slowly, as is the case at the present day withnbsp;Ceratozamia, Ginkgo, and Gnetum.

Brongniart ^ has distributed the seeds which he has examined among different genera according to their general form and the structure of thenbsp;testa. Of these, Cardiocarpus, Rhabdocarpus, Diplotesta, Sarcotaxus,nbsp;Taxospermum and Leptocaryon are flat seeds, and they are especially thenbsp;^orms which Renault thinks belonged to Cordaitae. The transverse sectionnbsp;Stephanospermum and Aetheotesta is simply circular. The formernbsp;Senus is distinguished by the extraordinary size of its pollen-chamber,nbsp;^¹^d its testa has a winged border forming a collar round the micropylarnbsp;^iid of the seed. In all the rest the transverse section shows three, sixnbsp;or eight edges of wings. In Trigonocarpus there are three flat edges,nbsp;^rid the testa is fissured in the edges. Hexapterospermum, Polyptero-�permum and Polylophospermum have six simple winged edges ; Ptycho-

testa has six wing-like duplications of the testa. The seeds of Eriotesta and Codonospermum have eight of these marginal projections. Eriotesta isnbsp;further distinguished by the nature of the surface of the testa, which isnbsp;entirely covered with close-set hair-like fibres swelling into a knob at thenbsp;apex. But the most remarkable form is seen in Codonospermum. Thenbsp;seed, which is depressed in the direction of the axis and has flat edges, hasnbsp;a wing like a circular collar on the margin of the flat basal surface, and innbsp;the same manner the entering vascular bundle is enclosed for some distancenbsp;in a tube-like process of the testa.

I do not venture to decide how far the genera described by Williamson^ coincide with those of Brongniart, though from the details of their internalnbsp;structure they may all be supposed to belong to the same group. They arenbsp;described under the names Cardiocarpon, Trigonocarpon, Malacotesta,nbsp;Lagenostoma, and Conostoma. Williamson agrees with Brongniart innbsp;speaking of the boundary-line of the nucellus-in all cases as the �nucularnbsp;membrane,� and of the boundary of the embryo-sac as the �perispermicnbsp;membrane.� In some forms, Lagenostoma for example, in which the apexnbsp;of the nucellus in the region of the pollen-chamber is split into two tissue-layers, the outer of these which is plicately sinuous is termed the � canopy.�nbsp;The seed described by Hooker and Binney^ has been again found bynbsp;Williamson and figured as Trigonocarpon olivaeforme. In the transversenbsp;section it shows the character of Tripterospermum, Brongn., but withnbsp;the difference that it has three slightly raised secondary ribs on eachnbsp;of the surfaces between the three wing-like projections. The beak-likenbsp;apex which is pierced by the micropylar canal is formed entirely of the hardnbsp;layer of the testa. It is a question whether the casts described by Heer � asnbsp;Rhynchogonium do not belong to this form. The genus Malacotesta, ofnbsp;which only one seed has been examined, seems to have had a single fleshynbsp;membrane and no hard endotesta.

Lastly, Dawson�S has sought to class with Brongniart�s genus Aetheo-testa certain fossils which have been found in England in the Upper Llandovery and Ludlow beds and in the Devonian foi'mation of Newnbsp;Brunswick. These were first described and named Pachytheca by Hooker�,nbsp;who inclined to regard them as fructifications of Lycopodinae. But theynbsp;have nothing whatever to do with Aetheotesta or with any seed of Gym-nosperms, as I have learnt from examination of specimens and sections, andnbsp;therefore we cannot with Dawson appeal to them to show that Nemato-phycus Logani, which occurs with them, is a Conifer. They are smallnbsp;spheroidal smooth bodies of an intense chestnut-brown colour and of different sizes; they are hollow in the centre, and the thick wall of the cavity

' Williamson (1), VIII, nbsp;nbsp;nbsp;� Hooker and Binney (1).nbsp;nbsp;nbsp;nbsp;^ Heer (5), vol. 41, t. 5.nbsp;nbsp;nbsp;nbsp;* Dawson (1),

p. 108; also (3) and (4), p. 306. nbsp;nbsp;nbsp;� Hooker (2) ; see also Etheridge in Hicks (i).

shows a radial structure. I have had the opportunity of seeing sections of the best-preserved specimens in the Jermyn Street Museum and fromnbsp;Thiselton Dyer, but I do not venture to express any opinion respectingnbsp;their place in the system; the truth is that I entertain some doubts as tonbsp;the vegetable nature of these remains. The fossils which J. M. Clarke ^ hasnbsp;recently described from the Devonian formation of N. America under thenbsp;names Sporangites Huronensis, Daws., and S. (Protosalvinia) bilobata,nbsp;Daws., appear to be similar objects. In the latter form several of the smallnbsp;bodies just described lie in a sac-like common envelope.

Hitherto we have considered only those flowers and seeds of Cordaiteae and any other gymnospermous forms, in which the structure can be madenbsp;out with certainty in the petrified remains. But it has more than oncenbsp;been remarked that the same and similar remains are often found in thenbsp;Coal-measures in the form of impressions, and that these have long beennbsp;described in the literature under a great variety of names. We must thennbsp;return to these forms in concluding the present chapter, and we may mentionnbsp;first a number of cases in which inflorescences have been found still attachednbsp;to the branches of Cordaitae which bore them; their diversity of appearance supplies further ground for the view which has been already expressed,nbsp;that the group was composed of a great variety of species, and that we cannbsp;at present only form a conjecture or general idea of the differences whichnbsp;Were developed in it, but are very far from having any real knowledge ofnbsp;them. A number of figures of these forms will be found in Grand� Eury^.nbsp;Slender branchlets are attached laterally to portions of leafy branches, andnbsp;bear in the axils of short scale-leaves clusters either of naked ovules or ofnbsp;small evidently male buds enclosed in scales. In one of the specimensnbsp;figured � the two kinds of lateral shoots stand side by side, which wouldnbsp;show that this species of Cordaiteae was monoecious, provided there hasnbsp;been no reconstruction ; but on this point I am left still in doubt. It seemsnbsp;^ remarkable fact that all these specimens show the flowering branches innbsp;definite relation to the leaves, but at the same time so much raised abovenbsp;^rgt;d out of their axils, that we may doubt whether they ought to be callednbsp;^xillary shoots. That there were differences as regards the position of thenbsp;inflorescence in different forms is shown by one figure^, in which the malenbsp;buds are not disposed in clusters on lateral branches, but occupy the sum-iruts of elongated branchlets which are placed in a tuft on the end of thenbsp;shoot. That there were differences also in the foliation of the floweringnbsp;branches is seen directly by comparing the impressions of which we arenbsp;speaking with Renault�s section-preparations, in which we found that thenbsp;owers, few in number, were actually immersed among strongly developed

^^rand�Eury(l),t.2,,f,5.

leaves. The figure of Poacordaites linearis, Grand� Eury in the text of Weiss� book^ shows essentially the same condition of things as thenbsp;figures in Grand� Eury; the few attached flowering branches bear malenbsp;inflorescences, and are marked by the small number of their lateral flower-buds and by the unequal length of the internodes developed between them.nbsp;Lesquereux^ also has figured a branch which resembles those of Grand�nbsp;Eury. Similar objects are extremely abundant, as may be supposed,nbsp;in the loose state, that is, not attached to the branches which bore them,nbsp;and the literature is full of illustrations of them. Grand� Eury� hasnbsp;figured a large number of these remains, among them male inflorescencesnbsp;which are remarkable for the length of the bract-scale which supports thenbsp;flower-bud This same form has been already described by Ettingshausen�nbsp;from the Coal-measures of Stradonitz in Bohemia under the name ofnbsp;Calamites Volkmanni, Ett. Examples will be found also in Goppertnbsp;Weiss Lesquereux � and Dawson ^; lastly, Schimper gives figures ofnbsp;many of these forms, and also reproductions of the more abnormal inflorescences, which have been described by Carruthers under the names ofnbsp;Antholithus anomalus and A. Lindleyi and are figured in Balfour Innbsp;these the axis bears lateral clusters of compressed heart-shaped seeds onnbsp;long stalks and begirt with a wing-like membrane which is emarginate atnbsp;base and apex. In the places mentioned and in almost every work whichnbsp;describes any number of coal-plants figures will be found of countless castsnbsp;of seeds, but as they have no importance to the botanist the reader isnbsp;referred for an account of them to Schimper�s work

DOLEROPHYLLUM, CANNOPHYLLITES, EPHEDRITES, GNE-TOPSIS, SCH�TZIA, DICTYOTHALAMUS, CALATHIOPS.

In the present chapter we shall consider a few gymnospermous types which are still imperfectly known and which seem to have little or no relation to one another.

The first to be noticed is the new and still very problematical genus Dolerophyllum, Sap., which might very properly have been discussed innbsp;Connection with other forms, and to which I allow so much prominencenbsp;only because Saporta and Marion ^ treat it as quite securely established,nbsp;and make use of it for the most extravagant speculations. It is foundednbsp;on some peculiar bud-like objects long since known in a silicified state fromnbsp;the Permian formation of Eastern Russia, which were named by Eichwald ^nbsp;Noggerathia G�pperti, and were till quite recently compared by G�ppert �nbsp;''�ith inflorescence-buds of Musaceae h Good figures of them are to benbsp;found in the authors last named and in Saporta and Marion The stoutnbsp;ovoid buds with a somewhat acute apex are formed of large probablynbsp;spirally disposed leaves, which follow closely upon and are rolled roundnbsp;quot;^ne another in the form of a sheath, and are traversed by numerous nervesnbsp;'vhich run everywhere at right angles to the margin, and here and there arenbsp;forked. G�ppert believed that he recognised on the cross fracture of thesenbsp;Convolute leaves a row of longitudinal air-passages, such as are often foundnbsp;Scitamineae ; but the result of Renault�s investigations into the anatomynbsp;�^f a specimen of this kind from the Ural is to show that this dependsnbsp;Entirely on the state of preservation, for the transverse section figurednbsp;f�y Saporta and Marion� from Renault�s drawings proves that the leaf isnbsp;everywhere formed by uniform thin-walled parenchyma, within which thenbsp;f^undles lie surrounded by parenchymatous sheaths. On the under side ofnbsp;^ch bundle is a longitudinal row of large cells, which are declared by thenbsp;fench authors to be gum-receptacles. The bundle itself is of peculiarnbsp;construction ; Saporta and Marion � say of it: � it exhibits the duplicated

1 ^ Saporta et Marion ('2). nbsp;nbsp;nbsp;quot; Eichwald (1), vol. i, t. l8, ff. 1-3.nbsp;nbsp;nbsp;nbsp;= G�ppert (3), t. 62, ff. 1-6.

1 nbsp;nbsp;nbsp;(6).nbsp;nbsp;nbsp;nbsp;5 Saporta et Marion (2), p. 71.nbsp;nbsp;nbsp;nbsp;^ Saporta et Marion (2), p. 73�

124 DOLEROPHYLLUM, CANNOPHYLLITES, EPHEDRITES, construction which is constantly observed in the stems described above,nbsp;and which is found in no existing Phanerogams except the Cycadeae.�nbsp;Judging from the figure I should say that the resemblance to the bundlesnbsp;in Cycadeae is not too striking; the bundle approximates on the transversenbsp;section to the form of a five-rayed star with the initial strand lying innbsp;the centre, and is surrounded by small-celled delicately walled tissue whichnbsp;may be supposed to be bast. The three under rays of the woody strandnbsp;are connected together, and will of course have been regarded as the � centrifugal xylem,� the upper rays which are separated by small intervals beingnbsp;the �centripetal xylem.� The epidermis of the under side is composed ofnbsp;palisade-like cells with thin conically convex outer walls. On the uppernbsp;side the cells are shallow, but their outer wall is very much thickened and isnbsp;prolonged over each cell into a thorn-like process. We have alreadynbsp;observed a similar state of things in Cordaitae. In other respects thenbsp;vascular bundles are so imperfectly preserved, as I have been ablenbsp;through Renault�s kindness to satisfy myself by inspection of the originalnbsp;preparations, that every definite statement about them must be taken withnbsp;caution.

With these buds then Saporta^ and Marion^ associate certain round entire leaves with a cordate base and auricles often overlapping one another,nbsp;which have the nervation of the leaves of the buds described abovenbsp;(Nervatio Cyclopteridis); these leaves have been repeatedly found atnbsp;St. �tienne by Grand� Eury, and are attached, almost at a right angle asnbsp;it would appear, to small portions of branches which are in some cases preserved at their base or appear in the cross fracture. Together with othernbsp;remains they form the Doleropteridae of Grand� Eury and are figured innbsp;a reduced but still recognisable form as Doleropteris pseudopeltata. Grand�nbsp;Eury��. Saporta�s name is connected with Grand� Eury�s nomenclature.nbsp;These leaves do in fact agree very well in habit with the convolute leaves ofnbsp;the buds before described ; still Saporta and Marion may be going too far,nbsp;unless they are in possession of proofs not yet given to the world, when theynbsp;maintain : � It is certain that the leaves and consequently the branchesnbsp;which they covered became detached at some time or other from largenbsp;conical buds,� amp;c. N�ggerathia Cyclopteroides, G�pp.�, is the only formnbsp;cited from the older literature as belonging to the leaves of Dolerophyl-lum, but Grand� Eury had already connected these with various species ofnbsp;the fern-genera Cyclopteris and Nephropteris as defined by Brongniart�.nbsp;Like Brongniart and Schimper'^, Grand� Eury inclines moreover to regardnbsp;all these objects as anomalous pinnae of the leaf-axes of Ferns, the so-callednbsp;Aphlebiae (see the chapter on Ferns), which are certainly not unlike them

in form But some of these remains also show the most decided resemblance to the leaves figured by Saporta and classed with Dolerophyllum and especially the point of transverse fracture of the stem is often to be seennbsp;in the angle of insertion. In fact this resemblance is much greater than innbsp;the case of N�ggerathia Cyclopteroides, G�pp., of which only one leaf isnbsp;known in a rather fragmentary condition. Any one may satisfy himself onnbsp;this point by comparing Saporta�s figures cited above with the following:nbsp;Cyclopteris obliqua, Brongn.^, C. reniformis, Brongn.�, C. obliqua, Brongn.''',nbsp;C. dilatata, Lindley and Hutt.�, C. obliqua, Brongn.�, C. rarinervia, G�pp.� Allnbsp;these remains from the Coal-measures, which have hitherto been regardednbsp;as extremely doubtful objects, would have their position secured to a welcome extent, if further investigation were to establish Saporta�s conceptionnbsp;of Dolerophyllae. Renault indeed has told me in conversation that henbsp;would place a part only of these Cyclopteridae with Dolerophyllum, andnbsp;leave the others with the Ferns. He lays great weight with respect to thisnbsp;question on the presence of the gum-receptacles in Dolerophyllum (seenbsp;above on p. 133), which he thinks he has recognised in certain impressionsnbsp;of Cyclopteris in the form of small longitudinal unevennesses like pencil-strokes between the nerves of the leaf-surface. To me it seems that Renaultnbsp;sees more in the sculpture of the impression than can be admitted withoutnbsp;further proof. Again, a portion of a branch with large roundish leaf-scarsnbsp;is figured in the work of Saporta and Marion so often quoted above, andnbsp;the explanation of the figure says of it: � supposed stem of Dolerophylleae.�nbsp;Why it should belong to that group is not apparent, especially since thenbsp;shape of its scars is difficult to reconcile with the bases of the leaves innbsp;question. The same remark applies to the fragments of male and femalenbsp;flowers referred by these authors to Dolerophyllae. Impressions of singlenbsp;scutiform scales with excentric stalks^ have been found in the Upper Coal-measures of Mt. Pel� near �pinac, showing on their under side numerousnbsp;small elliptical depressions disposed in radiating rows and filled with anbsp;Powdery substance which was seen to be pollen-grains ; they were thereforenbsp;Compared with stamens of Cycadeae. Their structure was ascertained bynbsp;the discovery of a silicified fragment, in which the pollen-sacs in the formnbsp;of elongated cylindrical tubes with their contents well preserved were foundnbsp;�unk in the tissue of the scale. The pollen-grains according to the drawingnbsp;given of them are ovoid and furnished on one side with two furrows close tonbsp;mie another, and their interior is entirely filled with a cellular body composed of large irregularly disposed elements. The original specimens, which

� Brongniart (1), vol. i, t. 61, f. 3. nbsp;nbsp;nbsp;� Erongniart (1), vol. i,

Lindley and Hutton (1), vol. ii, t. 90. nbsp;nbsp;nbsp;� Lindley and Hutton (1), vol. ii, t. 91 b.

Moppert (1), tt. 4 and 5, f. i. nbsp;nbsp;nbsp;' G�ppert (3), t. 8, f. 9.nbsp;nbsp;nbsp;nbsp;� Sapoi ta et Marion (2), p. 69.

origin have been described as Ephedrites, but they show little or nothing characteristic. The fructifications also from the Jurassic deposits of Siberia,nbsp;which Heer|^ assigns to his Ephedrites antiques, are more than doubtful.nbsp;Schenk�s^ excellent critical remarks on this subject should be consulted.nbsp;Renault � speaks of some of the seeds from the Coal-measures which werenbsp;noticed in the last chapter in connection with Cordaiteae, namely Sama-ropsis, Cardiocarpus orbicularis, Brongn., and Stephanospermum, as doubtful remains of Gnetaceae. In his explanation of the plate in Brongniartnbsp;he gives the following reason for his opinion as regards that form : � Thisnbsp;seed is surrounded by two envelopes which appear to be independent of onenbsp;another and not intimately connected together like the endotesta and sarco-testa in other seeds of the group of Cardiocarpeae ; it reminds us in thisnbsp;respect of certain seeds of Gnataceae, of Gnetum Thoa, for example, andnbsp;Gnetum urens. Since then there is a piece of the inner integumentnbsp;evidently remaining, we should in fact have three envelopes before us, as innbsp;Gnetum ; but it is confessedly very hazardous to conclude the number andnbsp;character of the integuments from the structure of the envelopes of thenbsp;seed, especially where, as in this case, the division between sarcotesta andnbsp;endotesta may very easily have been a consequence of maceration ofnbsp;the seed.

Lastly, the same author � describes as Gnetopsis elliptica certain fructifications which he has discovered in the pebbles from the Upper Coal-rueasures of Grand� Croix. In Saporta and Marion where these fossils ^re figured for the first time from Renault�s drawings, the genus is placednbsp;*iext to Ephedra. Then two more species were added to the genus,nbsp;Gnetopsis trigona and G. hexagona, Ren. and Zeill., forms found only asnbsp;impressions in the carboniferous mountain-district of Commentry. Thenbsp;remains of the flower of Gnetopsis elliptica are of complicated structure.nbsp;The transverse section (Fig. ii, D) shows two distinct opposite bract-likenbsp;leaf-forms with curved surfaces, which are traversed by numerous parallelnbsp;''vascular bundles of normal structure and normal arrangement, and are coverednbsp;on the inner side with long close-set hairs which fill the hollow of the leaf.nbsp;These leaves divide above, as we learn from successive transverse sections, intonbsp;an uneven number of apices, each of which is supposed by Renault to havenbsp;^ vascular bundle corresponding to it. Between the hairs which fill the innernbsp;space are seen the transverse sections of several ovules, the normal numbernbsp;oing four, so that there are two to the space enclosed by each of the twonbsp;enveloping leaves; Since the two pairs of ovules are not inserted at the samenbsp;evel on the summmit of the axis, they are seen at different heights on thenbsp;transverse section. Further irregularities often occur, the number of de-

g, nbsp;nbsp;nbsp;(5), vol. 411, t. 14.nbsp;nbsp;nbsp;nbsp;2 Zittel (1), p. 354.nbsp;nbsp;nbsp;nbsp;� Renault (2), vol. iv. * Brongniart

yj, t. y. 0 Renault (2), vol. iv, tt. 20, 21, 22. nbsp;nbsp;nbsp;Saporta et Marion (2), p. iSi.

Renault was good enough to demonstrate to me, have convinced me that we have here to do with correctly described and highly remarkable remains.nbsp;At the same time also it is the opinion of this author that no surer groundsnbsp;can be obtained at present for the determination of the plant to which theynbsp;belong, and the lively imagination of Saporta and Marion ^ is required tonbsp;enable us to conceive how they can write as follows: � we see the closenbsp;connection between the Dolerophylleae and the progymnospermic stage,nbsp;but this connection appears still closer when we examine the reproductivenbsp;organs of these plants, which thanks to the perspicacity of M. Renault andnbsp;the researches of M. Grand� Eury may be considered to be sufficiently wellnbsp;known.� Then the remains of the female flower, which offer but little that isnbsp;characteristic, are figured on page 76. A roundish scale-like leaf, destroyednbsp;by maceration on one side up to the vascular bundles, is supposed to havenbsp;borne in a depression on the middle line near the base an ovoid seednbsp;pointed at the upper end and showing striae-like fibres on the outside.nbsp;Seed and leaf are figured but not in connection with one another, and thenbsp;point of insertion on the leaf is not to be recognised. Saporta himself,nbsp;who, as has been often shown, is not too particular about proofs of connection, is induced on this occasion to make the following remark: � Wenbsp;give a figure of this curious organ, though it is still of somewhat doubtful character.� All this shows how little certainty there is at presentnbsp;with regard to the genus Dolerophyllum. The anatomy of the leaf is asnbsp;yet the only thing that can be made use of to determine its position andnbsp;affinities, and it seems to me to be Very doubtful whether we are justifiednbsp;on this ground only in introducing it into the alliance of Cordaitae andnbsp;Gymnosperms.

On occasion of discussing their Progymnosperms Saporta and Marion^ write as follows ; � Near the Dolerophylleae we should place a less-knownnbsp;but perhaps still more curious type, that of the Cannophylliteae ofnbsp;Brongniart (Megalopteris, Daws.). The Cannophylliteae appear to be tonbsp;the Dolerophylleae what the modern Stangeriae are to other Cycadeae.�nbsp;Then portions of a leaf of Cannophyllites Virleti, Brongn.�, are representednbsp;on page 79 k These fragments appear to me, notwithstanding the assertionsnbsp;just quoted, to be ordinary remains of fern-leaves with the nervation ofnbsp;Neuropteris, and Megalopteris Dawsoni, Hartt., from the Devonian bedsnbsp;of New Brunswick, figured by Dawson�, may very well belong to the samenbsp;group. Both Dawson and Lesquereux� consider these remains to benbsp;nothing more than leaves of Ferns.

No remains of the class of Gnetaceae have yet been determined with perfect certainty. Fragments of variously striated branches of Tertiary

^ Saporta et Marion (2), p. 74. nbsp;nbsp;nbsp;^ Saporta et Marion (2), p. 77.nbsp;nbsp;nbsp;nbsp;� Brongniart (7), p. 129-

* Saporta et Marion (2), p. 79. nbsp;nbsp;nbsp;� Dawson (1), t. 17.nbsp;nbsp;nbsp;nbsp;quot; Lesquereux (1), t. 24.

The tissue surrounding it was destroyed ; it could not therefore be determined with perfect certainty in which of the two parts its course lay. That portion of the integument which encloses the apex of the nucellus behavesnbsp;in a very peculiar manner, and may be compared perhaps with Lagenostoma,nbsp;Will, (see above on p. 130). It attains a considerable thickness and separatesnbsp;into a compact outer lamina (canopy ?) and a similar inner lamina, while thenbsp;cell-layer between the two is formed of extended filaments, which representnbsp;so many cells and traverse a broad intercellular space at some distance fromnbsp;each other. This looser tissue ceases of course at the micropylar canal,nbsp;vhere the outer and inner layer are in connection with one another. Thenbsp;margin also of the orifice of the micropyle is formed of a cup-shaped expansion, which is seen to be drawn out at two points into long filiform appendages (Fig. II, A, B). It is certainly possible, as Renault thinks, thatnbsp;the loose open tissue surrounding the micropyle may have served as anbsp;swimming-apparatus and the long filaments attached to it as organs ofnbsp;flight, and that these seeds therefore were adapted at once for transportnbsp;through the air and through the water; but we cannot grant more thannbsp;this. There seems to be much better foundation for his view, that thenbsp;drop of moisture excreted for the reception of the pollen-dust was caughtnbsp;between the two long cilia, which served therefore as conducting organsnbsp;iri the process of pollination. Organs of this kind must in fact have beennbsp;a necessity in the case of flowers buried among close-set woolly hairs andnbsp;overtopped by them.

From the account here given it would certainly be impossible to guess fhe reasons which have led Renault to place this genus among Gnetaceae.nbsp;l^ut these reasons appear at once when we employ his terminology, and saynbsp;for example with Saporta ^nd Marion ^: � the chief difference (betweennbsp;Gnetopsis and Ephedra) is that the involucre or exterior pseudo-ovariannbsp;�ntegument encloses four ovules seated on a receptacular cushion, instead ofnbsp;�^�'ly one.� That is to say, that the leaves which were just now termed bractsnbsp;^ust be explained to be imperfectly closing carpels, and are to be com-Pared in accordance with van Tieghem�s ideas with the outer coveringnbsp;the ovule of Ephedra and Gnetum. We may certainly incline to thisnbsp;''lew from van Tieghem�s stand-point, but even this does not compel us tonbsp;^dopt itj as will appear on referring to the artificial interpretation of thenbsp;female flower of Taxus given by that author. It follows that if the assign-'quot;g our genus to Gnetaceae really rests on a petitio principii, we can onlynbsp;properly say that it is a form of Gymnosperm, but that its affinities andnbsp;relations require further investigation.

In conclusion, we must mention here a number of remains of fructifi-' Saporta et Marion (2), p. i8i. K

veloped ovules being sometimes reduced to two or even to one only. The longitudinal section (Fig. ii, A, B)^ shows the summit of the obliquelynbsp;ascending axis expanded into a flat surface between the two leaves, andnbsp;the sessile ovules of the one leaf-axil inserted considerably higher upnbsp;than those of the other; it also makes us acquainted with their structuralnbsp;details. The nucellus is surrounded by a single integument only, which isnbsp;formed of a few cell-layers but becomes thicker at the apex, and shows

Fig. II. Female flowers of Gnetopsis elliptica, Ren. A and B longitudinal sections showing the envelope which incloses several ovules. C diagrammatic representation of the closed envelope. D transverse section of the samenbsp;showing an ovule and the sections of the numerous hairs in the form of dots. A and B after Saporta and Marionnbsp;C and D after Renault-h

important complications which must be noticed again presently. The apex of the nucellus encloses a broad pollen-chamber, in which are found globularnbsp;pollen-grains quite filled with the interior cellular body. The embryo-sacnbsp;is large and broad, and at its upper end are at least two archegonia; thenbsp;endosperm in the sac is extremely well preserved. A vascular bundlenbsp;enters at the base of each ovule and splits into four branches, which werenbsp;seen in a transverse section by Renault ^ running far up in the ovule andnbsp;lying free between the remains of the integument and those of the nucellus.

cations from the Coal-measures known only in impressions and of an entirely doubtful character. The name Schiitzia anomala, Gein., is givennbsp;by Geinitz' and Goppert ^ to certain racemose inflorescences, in which anbsp;short lateral stalk has the appearance of being enclosed in basket-likenbsp;involucres which conceal the seeds. There is perhaps a certain similaritynbsp;of habit between these forms and Gnetopsis. It is scarcely possible tonbsp;gather more than this from the ill-preserved impressions. The remainsnbsp;of another fossil flower, named by Goppert Dictyothalamus Schrollianus,nbsp;is found at Braunau in Bohemia and at Neurode in Silesia on the samenbsp;laminae of clay-slate with Schiitzia. This plant has the habit of Schiitzia,nbsp;but the lateral axes bear roundish clusters of small cylindrical bodiesnbsp;without an envelope. It seems natural to consider these objects as malenbsp;inflorescences, and Goppert and Schimper also and Schenk are of opinionnbsp;that they may belong to Schiitzia. Lastly, panicled inflorescences fromnbsp;the Culm of Rothwaltersdorf have been described by Goppert � under thenbsp;generic name Calathiops, but I can make out no further details from thenbsp;figure representing them. I have been unwilling to leave these forms unmentioned, though we shall certainly not arrive at a clear understandingnbsp;of them till they have been discovered in the petrified state ; for the presentnbsp;it is useless to speculate on their affinities. There is no need therefore tonbsp;examine Nathorst�s * view that they are Balanophoreae.

Goppert (3), tt. 23, 24. nbsp;nbsp;nbsp;^ Goppert (3), t. 64.nbsp;nbsp;nbsp;nbsp;* Nathorst (5).

VIL

FILICES.

The Ferns are known to belong to some of the oldest living vegetable types. So far as it is possible to judge of the character of the generalnbsp;vegetation at any given time from the remains preserved to us in the fossilnbsp;state, we see them continually increasing in the number of individuals andnbsp;species from the most recent formations backwards to the Carboniferousnbsp;period. The Devonian beds also are rich in beautiful and well-characterisednbsp;Ferns. On the other hand, there seems to be no satisfactory example ofnbsp;this group of plants from Silurian deposits, for Eopteris Morieri described by Saporta^ from the Middle Silurian roofing-slates of Angers, ofnbsp;which I have seen fine specimens in the collection of the Royal Bergaka-demie at Berlin, is certainly of Inorganic origin, being formed of dendriticnbsp;deposits of iron pyrites. The midrib of the apparent Fern-leaf is thenbsp;infiltration-canal ; the pinnulae, which are very dissimilar in size and form,nbsp;show crystalline structure, and this was mistaken for the nervation of thenbsp;leaf.

The stems, leaf-stalks and leaves of Ferns are almost always found separate from one another and in a more or less fragmentary condition, andnbsp;this is especially the case with the many known large and copiouslynbsp;branched leaf-forms, of which we only now and then see fine entirenbsp;specimens. Isolated pinnules are all that occur of some forms; it may benbsp;eoncluded from this that they separated regularly from their axes, resembling in this respect many of our living Ferns, Marattia, for exanaple,nbsp;hfidymochlaena, Nephrolepis and others. It is wonderful to find in thenbsp;clay-slates of the Coal-formation such numbers of impressions of quitenbsp;young leaves in the bud-state. These are recorded in palaeontologicalnbsp;^orks under the generic name of Spiropteris. Leaf-stalks and fragments ofnbsp;^i-stalks also are constantly occurring, more particularly and in unusualnbsp;^hundance in the Coal-measures, and they are readily recognised on refuse-^Ps m coal-mines by their glistening black surface which is rough withnbsp;�^all irregularly disposed hairs. In this condition they are, botanically

speaking, of no value; the contrary is the case when they are petrified and it is possible to determine their inner structure. All such leaf-stalks arenbsp;usually comprehended under the name Rachiopteridae. The same may benbsp;said of the stems, which form a large portion of the fern-remains preservednbsp;to us ; they, like the Rachiopteridae, can only in the very rarest instances benbsp;referred with certainty to particular given leaves. It is true that we notnbsp;unfrequently find the two kinds of organs spoken of in the literature asnbsp;belonging to one another, but statements of this kind rest, except in a fewnbsp;cases ^ on conclusions from the fact that the parts occur together in thenbsp;strata, and of such conclusions we have already said what is needful in thenbsp;introductory chapter.

Fern-leaves furnish perhaps the one instance in which systematic botany has received a direct impulse from palaeophytology. Our entirenbsp;fern-system is founded on the nature of the fructifications, and these arenbsp;not often to be seen on the fossil leaves, and when present are usuallynbsp;indifferently preserved. When then Brongniart ^ addressed himself to thenbsp;task of classifying all known fossil fern-leaves, the number of which wasnbsp;very considerable even then, and perceived that the few fructifications withnbsp;which he was acquainted could be of no use to him, he seized with hisnbsp;wonted energy and precision on the only expedient which presented itself,nbsp;namely, the course of the nerves ; and upon this character, to which littlenbsp;attention had been paid up to that time, he founded a classification of fossilnbsp;Ferns which is confessedly artificial and not in accordance with that of recentnbsp;forms. Brongniart�s method was afterwards applied, as we know, by Presl �nbsp;especially and by A. Braun * to living species, and in the hands ofnbsp;Mettenius� above all others it proved to be extremely fruitful as a subordinate principle of division. G�ppert who had in the meantime becomenbsp;acquainted with a number of fossil fructifications, thereupon attempted tonbsp;combine Brongniart�s classification with that of the botanists, but thenbsp;attempt was an entire failure and he himself subsequently abandoned it;nbsp;his genera defined and named, some simply after Brongniart, others according to the fructifications, others again from their resemblance to recentnbsp;genera, run in confusion one into another, and no connected view of thenbsp;whole system is possible since the main principles of division are incommensurable. Systematists have since then been repeatedly guilty of thisnbsp;fault in logic; Schimper�saccount of these forms especially suffers fromnbsp;the same cause.

It was soon felt to be necessary to break up the great form-groups which Brongniart had founded on the course of the nerves, into furthernbsp;divisions. Systematists have often employed for this purpose the form and

� Schimper (3), t. 40, and Sternberg, Graf von (1), Heft 5-8, t. 59. nbsp;nbsp;nbsp;� Brongniart (1^-

Presl (1\ nbsp;nbsp;nbsp;�* A. Braun (1). Mettenius (1).nbsp;nbsp;nbsp;nbsp;� G�ppert (2).nbsp;nbsp;nbsp;nbsp;'� Schimper (1).

mode of branching of the whole leaf, and this course might be defended on the ground that these differences are also employed as good subordinatenbsp;marks in dealing with living forms. But genera such as have been recentlynbsp;founded by Stur^ and Zeiller^ (Diplotmema, Stur, Mariopteris, ZeilL), whichnbsp;rest solely on the form of a leaf with one or two bifurcations, as innbsp;Gleichenia, and contain species with different kinds of nervation, cannotnbsp;possibly find a place in any logical development of Brongniart�s system.nbsp;And as their value is entirely relative so long as we have no proper knowledge of their fructifications, the gain resulting from their establishment, ifnbsp;not altogether doubtful, must still be very small.

It is obvious that we must remain in uncertainty with respect to the configuration of the whole leaf in the many species which we know only innbsp;single detached pinnules. Imperfect remains of this kind must simply benbsp;entered under the names of the types of nervation to which they belong,nbsp;and which are used as generic names, until further fortunate discoveriesnbsp;teach us better. This proceeding is attended with an evil which is in somenbsp;cases unavoidable, namely that isolated pinnae of the same leaf are repeatedly and unconsciously registered under different names in different parts ofnbsp;the system. A considerable number of leaves found in the Coal-measuresnbsp;have in addition to the normal pinnules of the lamina of the leaf a secondnbsp;kind of pinnae of another shape and often with an entirely different nervationnbsp;(Fig. 13), which grow in numbers either from the surface of the main rachisnbsp;or at the base of the rachides of the second order, or are confined to thenbsp;base of the leaf-stalk. These anomalous pinnae are now usually termednbsp;Aphlebiae, but they are noticed in the literature under various names. Thenbsp;same phenomenon occurs also, though rarely, in living Ferns ; I have myselfnbsp;seen only two cases of the kind. The first is the well-known Hemitelianbsp;capensis, R. Br., common in botanic gardens, in which two much-branchednbsp;Aphlebiae appear on each side of the base of the leaf-stalk ; a figure of thisnbsp;species will be found in Schimper �. A second undetermined species, whichnbsp;unfortunately has since died, I remember to have seen in the botanic gardennbsp;Strassburg. A very excellent and complete account of these structuresnbsp;bas been given by Stur'^, who compares them with the stipular formationsnbsp;uf the Marattiaceae, and inclines to the belief that every fossil fern-leafnbsp;quot;'hich bears these Aphlebiae must therefore belong to that family. I can-uot assent to this view, on account of the recent plants just mentionednbsp;quot;'bich bear Aphlebiae and belong to the family of Cyatheaceae. I nownbsp;give a list of all the figures which have come to my knowledge, which shownbsp;Aphlebiae in connection with the leaf which bears them. They are these ;nbsp;(1) Sphenopteris crenata, Lindl. and Hutt., with the Aphlebia Rhacophyl-

lum adnascens, Lindl. and Hutt. (Fig. 12, i)\ (2) Pecopteris dentata, Gein. not Brongn., with Rhacophyllum filiciforme, Gutb.^ (3) Odontopterisnbsp;Reichiana, Gutb., with Cyclopteris trichomanoides, Brongn.^ (4) Oligo-carpia quercifolia, G�pp.* (5) Neuropteris Loshii, with Cyclopteris trichomanoides�. (6) Pecopteris Radnicensis, Strbg, with Aphlebia tenuiloba�.

(8) nbsp;nbsp;nbsp;Sphenopteris (Oligocarpia) for-mosa, Gutb.* (9) Sphenopteris (Di-plotmema) acutiloba, Strbg.� (10)nbsp;Sphenopteris coralloides, Gutb.^�nbsp;(11) Lesleya grandiSj Lesq.^^ (12)nbsp;Pecopteris dentata,with Rhacophyllum laciniatum

There are a few fossil fern-leaves which can find no place in Brongniart�s system because, owingnbsp;either to the bad state of preservation or to the stout leathery consistence of the lamina of the leaf,nbsp;the nervation is not distinctlynbsp;shown in any of the remainsnbsp;hitherto observed. Such formsnbsp;can of course only be given in annbsp;appendix ; and this is the case alsonbsp;with another series of forms, whichnbsp;do not certainly belong to thenbsp;Ferns but may most of them benbsp;quite as well classed with Cyca-deae, as has been already remarkednbsp;(see p. 87). In fact one of thesenbsp;genera, Thinnfeldia, Ett.^� is particularly compared by its authornbsp;with Phyllocladus. We shall have to return once more to these doubtfulnbsp;forms in a future page.

It is impossible for me to treat at length of the countle.ss fern-leaves which have been preserved in the fossil state, for I have occupied myself

' Lindley and Hutton (1), vol. ii, tt. too, loi; Schimper (1), t. 48, ff. i, 2; Zittel (1), p. 143; O. Feistmantel (3), t. 66. � Geinitz (5), t. 25, ff. 11-14; Schimper (1), t. 48, ff. 3-5. ^ Geinitznbsp;(5), t. 26, f. 7 ; Grand� Eury (i), t. 12, p. 113 ; Zittel (i), p. 122.nbsp;nbsp;nbsp;nbsp;* Stur (5), t. 15, f. 12.

^ Roehl (1), t. 17 ; Geinitz (4), Heft 2, t. 4, ff. 2, 3. nbsp;nbsp;nbsp;quot; Sternberg. Graf von (1), t. 58,'ff. i, 2.

� Lesquereux (3), t. 8, f. 5. nbsp;nbsp;nbsp;* Zeiller (7), t. to, f. 12.nbsp;nbsp;nbsp;nbsp;� Zeiller (7), t. 11, f. 5.nbsp;nbsp;nbsp;nbsp;1� Zeiller

(7), t. 12, ff. I and 8. nbsp;nbsp;nbsp;� Lesquereux (1), vols. i. and ii, t. 15, f. 3.nbsp;nbsp;nbsp;nbsp;Fontaine and White

but little with them. Such an account of them moreover would be foreign to the plan of this work, since it would offer very little that is of interest fromnbsp;the botanical point of view; moreover, our living material supplies us withnbsp;a much greater variety of forms of nerve-distribution. But that my worknbsp;may not seem too unconnected and fragmentary, I introduce here a very briefnbsp;account of the main types of nervation accompanied with a few examples.

Nervatio Pecopteridis is characterised, as is well known, by pinnately arranged tertiary nerves, which arise at a rather broad angle from thenbsp;secondary nerves, and, remaining simple or bifurcating, run straight and freenbsp;to the margin. Nervatio Sphenopteridis is closely allied to it, beingnbsp;essentially distinguished only by the very acute angle which the tertiarynbsp;nerves form with the secondary. These two types of n�rvation are notnbsp;sharply separated from one another ; the form which is as nearly as possiblenbsp;intermediate between them is named by Mettenius Nervatio Eupteridis,nbsp;and the genus Alethopteris may be quoted as an example of this typenbsp;among fossil Ferns, though it is actually distinguished from Pecopterisnbsp;more by habit than by very marked chai'acters. In many cases the incisionsnbsp;in the leaf follow the course of the nervation with great exactness, so thatnbsp;the extreme point of the leaf is only traversed by a median nerve, and thisnbsp;produces Mettenius� Nervatio Caenopteridis. But all fern-leaves whichnbsp;have this character are as a matter of fact reckoned with Sphenopteris,nbsp;though some of them may on closer examination be found to resemblenbsp;Pecopteris rather than Sphenopteris as regards the angle of emergence ofnbsp;the nerves. This may be the case, for example, with Sphenopteris Hoen-inghausii, Brongn., to judge by Schimper�s figured Pecopteridae andnbsp;Sphenopteridae are found in abundance throughout the whole series ofnbsp;Palaeozoic and Mesozoic formations. In the Cainozoic deposits the Fernsnbsp;are on the whole in a minority as compared with other plants. They predominate in the Coal-measures especially, and by far the greater number ofnbsp;^arge and highly compound leaves belong to that formation. The oldestnbsp;known Ferns from the Upper Devonian beds and the Culm are for the mostnbsp;part, though not entirely, Sphenopteridae with unusually complete divisionnbsp;of the lamina of the leaf, which appears to be reduced everywhere to anbsp;narrow margin accompanying the nerves. Such forms are usually describednbsp;'n the literature as Hymenophyllites, Todea or Rhodea ; as examples maynbsp;ke mentioned Rhodea patentissima, Ett.^ from the Culm, Todea Lipoldi�nbsp;from the roofing-slates of Moravia, Sphenopteris Condrusorum ^ (Psilo-Phyton, Cr�p.�) from the Devonian formation.

Nervatio Taeniopteridis is more sharply defined. Here the tertiary nerves emerge almost at a right angle and run in a straight line to the

� Schimper (1), t. 29. nbsp;nbsp;nbsp;^ Schimper (2), p. 108.nbsp;nbsp;nbsp;nbsp;� .Stur (6), t. 11, f. S.

margin of the leaf. If they fork, which is very commonly the case, their branches diverge at a very acute angle and soon become parallel to onenbsp;another. Oleandra, Scolopendrium, Marattia supply examples amongnbsp;recent Ferns. The Taeniopteridae are on the whole characteristic of thenbsp;Mesozoic formations ; the best known forms are Taeniopteris marantacea,nbsp;PresP (Danaeopsis marantacea, Schpr) from the Letten Kohl and T. Miinsterinbsp;from the Rhaetic beds. Both species have simply pinnate leaves of considerablenbsp;size. Forms with a simple lamina not pinnately divided are termed Olean-dridium. A large number of simple leaves of more than usual size havenbsp;been described by O. FeistmanteP from the Lower Gondwanas (Trias) ofnbsp;India under the name Macrotaeniopteris. Forms of this type are very rarenbsp;in the Palaeozoic formations, but some examples are figured in Lesquereux�nbsp;(Taeniopteris Smithsii, Megalopteris). I am not indeed sure that Megalo-pteris belongs to this division ; on this point the literature cited above innbsp;connection with Cannophyllites should be consulted.

In Nervatio Neuropteridis the tertiary nerves come off at an acute angle, but they describe a curve convex to the midrib as they run to thenbsp;margin of the leaf, with which both they and any parallel ramificationsnbsp;which may arise form nearly a right angle. If the curvature of the tertiarynbsp;nerves diminishes, Neuropteris may come near to Sphenopteris or Peco-pteris; on the other hand it approaches Nervatio Cyclopteridis, the nextnbsp;type to be mentioned, and may indeed be very like it, if the median nervenbsp;is only a little more strongly developed than the lateral. In practice it isnbsp;often difficult to distinguish it from Cyclopteris, as may be seen bynbsp;comparing, for example, Odontopteris obtusiloba, Naum, and Neuropterisnbsp;Loshii, Brongn., which are exactly alike in the form of the leaf. Innbsp;Schimper�� we find Cyclopteris and Neuropteris united for this reasonnbsp;into one family. The true Neuropteridae are entirely confined to thenbsp;Palaeozoic formations; figures of characteristic forms are to be found innbsp;Schimper

Nervatio Cyclopteridis is distinguished from Nervatio Neuropteridis by the absence of a median nerve. Numerous nerves of equal strength enternbsp;the lamina of the leaf and bifurcate repeatedly as they run in a curvenbsp;which is convex towards the apex of the leaf, and at length form a rightnbsp;angle with the margin. Various leaves of this type are found in thenbsp;oldest deposits along with the previously mentioned Sphenopteridae; onnbsp;the whole the Cyclopteridae are less abundant in the Mesozoic formations.nbsp;But there are some forms belonging to the present vegetation which follownbsp;this type of nervation. Various genera have been distinguished in the

� Schimper (1), tt. 37, 38. nbsp;nbsp;nbsp;'�* Pal. Ind., ser. xii. �* Lesquereux (1), t. 35, f. 7, and t. 24.

Schimper (1). nbsp;nbsp;nbsp;� Schimper (1), t. 30, ff. ii, 12, and (2), p. 116, t. 32.

group of Cyclopteridae according to the shape of the lamina of the leaf, one or two of which may be noticed because their great antiquity makesnbsp;them particularly interesting. One is the Devonian Palaeopteris, Schpr;nbsp;the large handsome bipinnate leaves of P. hibernica, Forbes, are characteristic of the Old Red Sandstone of Ireland, and will be found figured innbsp;Schimper^. Several other species are known, chiefly from Canada^.nbsp;Triphyllopteris Collombi � and Cardiopteris K�chlini ^ are found in thenbsp;Culm together with finely divided Sphenopteridae. The latter plant isnbsp;marked by its fine roundish pinnae which are attached to the rachis by anbsp;broad base. Most of the forms of this type from the Coal-measuresnbsp;belong to the genus Odontopteris �.

After elimination of the genera founded on the form of the entire leaf, we have still a remainder of single pinnae of a highly problematical character. Some of the forms which were once classed with themnbsp;are now seen to be leaves of Salisburieae, and have been already noticed innbsp;their proper place (see p. 6a); others are certainly Aphlebiae belonging tonbsp;various species of Ferns, the nervation of Cyclopteris being the prevailing,nbsp;though not perhaps the only, kind in these anomalous pinnae. If Saporta�snbsp;views respecting the Dolerophyllae discussed above on p. 125 should evernbsp;be confirmed, a number of Cyclopteridae would once more be included innbsp;that group.

If now we proceed to the forms in which the nerves anastomose, we have first Nervatio Goniopteridis, which arises out of Pecopteris when thenbsp;corresponding tertiary nerves which proceed from every two adjoiningnbsp;secondary nerves anastomose with one another. This may happen, as wenbsp;know, in the case of all or sometimes only of the lowermost of the tertiarynbsp;nerves. A number of such Goniopteridae are known from the Tertiarynbsp;formations but it would take too long to ascertain to what extent theynbsp;and the allied nervation-forms, Goniophlebii, Pleocnemiae, Cyrtophlebii, etc.nbsp;are distributed through the Mesozoic deposits, for the figures and descriptionsnbsp;nf authors are not clear and distinct enough for the purpose. The formsnbsp;m question are however usually collected together under the generic namenbsp;of Phlebopteris; all that have simple anastomosing nervation havenbsp;extremely few representatives in the Palaeozoic formations, the two chiefnbsp;types, both belonging to Goniopteris, appearing in the Carboniferous speciesnbsp;tjoniopteris (Diplazites) emarginata^ and G. arguta*.

Of fossil genera belonging to types with complex anastomoses we find that the greater number are also first seen in the Mesozoic formations,nbsp;t^'ily two of these are older and peculiar to the Coal-measures, Dictyo-

(!)� t- 36, and (2), p. 113. nbsp;nbsp;nbsp;^ Dawson (1).nbsp;nbsp;nbsp;nbsp;� Schimper (2), p. 114.nbsp;nbsp;nbsp;nbsp;* Schimper

t. 35, and (2), p. ii8. = Schimper (2), t. 30, f. 14, and (2), p. 12 r. � Schimper (1), and raun (1).nbsp;nbsp;nbsp;nbsp;^ Goppert (2), t. 16, ff. i, 2.nbsp;nbsp;nbsp;nbsp;� Brongniart (1), t. 108, ff. 3, 4.

pteris, Gutb. ^ and Lonchopteris The former developes the nervation of Ophioglossum, an uniform network of polygonal meshes; in the latternbsp;there is also a distinct midrib, so that the habit is that of some recentnbsp;species of Pteris, Pt. aurita, for example.

Of Mesozoic forms belonging to this group two series may be distinguished ; one of those in which the meshes of the network are all alike and separated by nerves of equal strength, as in the species from the Coal-measures just mentioned, the other of those in which nerves of unequalnbsp;development form by their anastomoses meshes of a higher and a lowernbsp;order, answering therefore to some extent to Mettenius� types, Anaxetum,nbsp;Drynaria, and Drynaria appendiculata.

Of the first series the genus Sagenopteris, Presl, has the first claim to notice. Sagenopteris rhoifolia, Presl, the best-known species, is peculiar tonbsp;the Rhaetic beds, and is found both near Bamberg and in Schonen^. A fewnbsp;other species belong to the Lias and the Lower Oolite beds. At thenbsp;extremity of the long leaf-stalk is the lamina composed of four pinnaenbsp;which spring from the same point. The ovate pinnae have a nervationnbsp;like that of Ophioglossum and show no trace of a median nerve. Anbsp;number of genera with similar nervation have been described by O. Feist-mantel from the Lower Gondwanas (Trias) of India, from deposits innbsp;Australia overlying the Coal-measures, and from South Africa^. Suchnbsp;are Palaeovittaria with leaves of probably the same structure as those ofnbsp;Sagenopteris, and forms with simple ligulate leaves like Gangamopterisnbsp;and the genus Glossopteris �, which is said by Feistmantel to be providednbsp;with a median nerve; lastly, the strange Belemnopteris with a simplenbsp;sagittate leaf-blade. The different attempts of authors to prove thatnbsp;Sagenopteris has its place with Marsileaceae will be noticed in discussingnbsp;that group.

From the second series of genera the Rhaetic form Thaumatopteris Miinsteri, Gopp., may be selected for notice as the one with which we arenbsp;best acquainted ; many good figures of it are to be found in differentnbsp;authors �. The deeply sinuate pinnatifid leaf-segments combine to formnbsp;a handsome palmate sympodial leaf-blade. Clathropteris, Brongn.�^ andnbsp;Dictyophyllum, Lindl. and Hutt. � are also from the Rhaetic beds, butnbsp;Dictyophyllum rugosum also occurs in the Oolite of Scarborough.nbsp;Camptopteris, Preslwith a handsome leaf like that of Thaumatopteris, isnbsp;peculiar to the Keuper.

It remains only to notice in a few words those leaf-forms which cannot be regarded as certainly belonging to the Ferns. One of them, the

� G�ppert (1), 5 and 6, t. 3. nbsp;nbsp;nbsp;� Brongniart (1), t. 131.nbsp;nbsp;nbsp;nbsp;^ Zittel (1), p. 155 ; Schenk (3), t. 12 ;

Nathorst (2), t. 4, iif. 3-5. nbsp;nbsp;nbsp;* Pal. Ind., ser. xii, with numerous figures; O. Feistmantel (1), III.

^ Schimper (2), p. 134. nbsp;nbsp;nbsp;* Zittel (1), p. 137 ; Schenk (3) ; Nathorst (2); G�ppert (1), i and 2,

tt. 1-3. nbsp;nbsp;nbsp;� Zittel (1), p. 13S.nbsp;nbsp;nbsp;nbsp;� Schimper (1), t. 41, f. 22.nbsp;nbsp;nbsp;nbsp;� Schimper (1), t. 42, f. 4.

genus Otozamites (Otopteris, Schenk), has been already sufficiently considered in the chapter on Cycadeae, The first therefore to be mentioned in connection with Dictyopteridae is the genus Dictyozamites, Oldh. fromnbsp;the Upper Gondwanas (Jura?) of the Rajmahal hills on the Madras coast,nbsp;which O. FeistmanteU has described at length and has illustrated withnbsp;numerous figures. The long imparipinnate leaves had been alreadynbsp;discussed by Oldham and Norris in a previous chapter^ of the same worknbsp;under the name Dictyopteris. They show the greatest resemblance in habitnbsp;to those of Otozamites; the pinnules inserted on the upper side of thenbsp;rhachis are attached to it by the middle portion of their broad base, andnbsp;have somewhat large overlapping auricles on the upper and under side.nbsp;But their nervation has altogether the character of Sagenopteris, and therenbsp;is no conspicuous median nerve. Much as their habit would incline us tonbsp;rank them with Cycadeae, we cannot do so at present, for we know as yetnbsp;of no form of that group which has reticulate nervation. The doubt cannbsp;be solved only by finding fresh specimens of this apparently rare fossilnbsp;showing the fructification or at least the inner structure. Dichoneuronnbsp;Hookeri is a leaf also with reticulate nervation, which Saporta� hasnbsp;described from the Permian formation of Eastern Russia, and which hadnbsp;been placed by Brongniart^ among N�ggerathiae. Its lamina is bifurcated,nbsp;and the segments are irregularly toothed and incised. I cannot imaginenbsp;why Saporta considers this to be the leaf of one of his Proangiosperms; Inbsp;have noticed this fossil only because he has so explained it.

The genus Nilssonia again is very like Cycadeae, and reminds us of certain Pterophyllae with short blunt pinnae-like lobes. From its habitnbsp;it would at first be included among Pterophyllae, as is done by Schimper �,nbsp;who like G�ppert ** and Nathorst even gives to Nilssonia species which arenbsp;generally considered to belong to Pterophyllae, for example Pterophyllumnbsp;comptum�, Lindl. and Hutt., from the Oolite of Scarborough. He hadnbsp;previously � in compliance with Schenk�s views dealt with it among thenbsp;Ferns. In Nathorst also, who ranks it with Cycadeae, will be found goodnbsp;figures and a careful examination of the genus. The principal species,nbsp;Nilssonia polymorpha, Schenk, is peculiar to the Rhaetic formation, and isnbsp;very abundant both in Franconia and in Schonen; two allied species arenbsp;found with it in the same localities. How far other forms from the Liasnbsp;s-nd the Lower Oolite belong to Nilssonia is difficult to determine owing tonbsp;the resemblance to Pterophyllum. The ribbon-like obtuse leaves ofnbsp;Nilssonia polymorpha vary greatly in form, sometimes having the whole ornbsp;large portions of the margin entire, but being more often divided by lateral

O- Jeistmantel (1), l; Pal. Ind., ser. ii, vol. i, pt. iv. nbsp;nbsp;nbsp;^ Pal. Ind., ser. ii, vol. i, pt. i.

Saporta (11). * Brongniart (5). � Schimper (2), p. 225. nbsp;nbsp;nbsp;� G�ppert (8). �� Nathorst (2).

Schimper (2), t. 45. nbsp;nbsp;nbsp;� Schimper (1), vol. i, p. 488.nbsp;nbsp;nbsp;nbsp;� Schenk (3), tt. 29-31.nbsp;nbsp;nbsp;nbsp;� Nathorst (2).

incisions into pinnae which touch one another and may be of unequal breadth. Similar conditions have been noticed above in the case of species of Ptero-phyllum ; but in these, as Nathorst rightly observes, the lamina is insertednbsp;exactly laterally, whereas its lines of insertion in true Nilssoniae are movednbsp;quite to the upper side of the rhachis and brought close together. The formnbsp;also of the individual segments shows not unimportant differences. Delicatenbsp;unbranched nerves run from the strong midrib perpendicularly to the marginnbsp;of the leaf, and are separated from one another by raised strips. If in spitenbsp;of all this agreement with Pterophyllum I still prefer to treat of this genusnbsp;amongP'erns, it is because in Schenk�s^ figures of the plant we see portionsnbsp;of leaves in which there are small roundish protuberances on the under sidenbsp;of the leaf in regular rows and parallel to the nervation ; these he considersnbsp;to be remains of sori, and though this has not been certainly proved, yetnbsp;from the regular disposition of these objects I consider Schenk�s view morenbsp;probable than that of Saporta who takes them for leaf-fungi.

A genus with the nervation of Neuropteris and calling for notice in this place is Thinnfeldia, Ett., which in its typical species belongs tonbsp;the Rhaetic deposits and to the angulatus-beds of the Lower Lias. Itnbsp;was first accurately described by Ettingshausen � from Steierdorf in thenbsp;Banat, and next by Schenk ^ from the neighbourhood of Bayreuth. Anbsp;detailed description of it, accompanied with good figures, is to be found alsonbsp;in Saporta Another species, Thinnfeldia crassinervis, has been describednbsp;by Geinitz � from the Rhaetic beds of the Argentine Republic. A speciesnbsp;from deposits in Australia above the Coal-measures has been referred bynbsp;O. Eeistmantel to this genus, but as it shows the nervation of Cyclopterisnbsp;it is a doubtful Thinnfeldia. The thick solid leaves of Thinnfeldiae arenbsp;simply pinnate; the entire or lobed pinnae are connected together at thenbsp;base by a margin of tissue which accompanies the midrib. In Ettingshausennbsp;and Geinitz they are represented with a forked division in the middle ofnbsp;the lamina. The resemblance to Phyllocladus on which Ettingshausennbsp;insists, and which Nathorst� also admits with some reserve, is, as Schenk **nbsp;has shown, not very important. The nervation, that is to say, is essentiallynbsp;different, it is the consistence only of the leaves which supplies a point ofnbsp;comparison. After Schenk�s excellent discussion of the question therenbsp;would be no reason for doubting that these leaves are the remains of Eerns,nbsp;if stomata were not found on both sides of them, and if the stomata werenbsp;not .slightly sunk beneath the epidermis and walled round by the adjacentnbsp;cells which rise above them. The latter structure is very common innbsp;Cycadeae and Coniferae ; it has never been observed by Schenk in Ferns.

� Schenk (3), t. 21, ff. i, 2. nbsp;nbsp;nbsp;� de Saporta (4), vol. ii, p. 41.nbsp;nbsp;nbsp;nbsp;� von Ettingshausen (2).

* .Schenk (3), tt. 26, 25-, and Schimper (1), t. 85. nbsp;nbsp;nbsp;^ de Saporta (4), vol. i, p. 340.nbsp;nbsp;nbsp;nbsp;� Geinitz

(6). nbsp;nbsp;nbsp;� Eeistmantel (1), in. * Nathorst (2).nbsp;nbsp;nbsp;nbsp;� Schenk (3).

He therefore does not decide for one or the other view, so long as the fructifications are unknown, and inclines to see in Thinnfeldia and its alliesnbsp;a group intermediate between Ferns and Gymnosperms. Though this isnbsp;in fact a possible supposition, for we shall be compelled by other observations, as in the case of Lyginodendron, to assume the existence of such intermediate groups, yet I would point out that Lomatopteris^ and Cycadopteris^,nbsp;genera especially comparable with Thinnfeldia and for which Saporta�s �nbsp;description should be consulted, are seen to be far more like Ferns. Thesenbsp;genera are represented in the Jurassic system by a large number of species.nbsp;In Cycadopteris Brauniana, common in the district of Vicenza, Zignonbsp;believes that he has discovered the sori; these according to his figure,nbsp;which is not indeed very convincing, are like strokes following the nerves,nbsp;and each is bounded by the two stout lips of an indusium.

The genus N�ggerathia was founded by Sternberg in 1823 on a pinnate leaf common in the Radnitz beds of the Bohemian Coal-measures. Thenbsp;specimen was figured as N�ggerathia foliosa, Strbg.^ This species is atnbsp;present restored to its position as the representative of the type ofnbsp;N�ggerathia, now that we are clear of the confusion caused by Brongniartnbsp;when he united a mixed multitude of heterogeneous forms under this name.nbsp;Of these forms, Ginkgophyllum (N�ggerathia flabellata) Dolerophyllumnbsp;G�pperti, Sap.'^, Dichoneuron Hookeri, Sap.*, and Macropterygium Bronnii,nbsp;Schpr (N�ggerathia vogesiaca, Bronn)�, have already been considered. Goodnbsp;figures of the large handsome pinnate leaves of N. foliosa are found in O.nbsp;FeistmanteH� and in the illustrations accompanying the text of Stur�s work^fnbsp;The pinnae are wedge-shaped with a rounded anterior margin, and thenbsp;nervation which belongs to the type of Cyclopteris is unusually close andnbsp;fine. The habit of these leaves recalls certain forms of Cycadeae (Spheno-zamites), because the pinnae which are inserted obliquely on the rhachis andnbsp;a little to one side overlap and cover one another. For this reason thenbsp;genus is by most authors placed among Cycadeae, by Schimper^^^ fornbsp;example, by Saporta and by Geinitz

The view that N�ggerathia belongs to the Ferns has quite recently made its appearance, and is due to Stur�s careful examination of specimensnbsp;in fructification ; it was at once adopted by K. and O. Feistmantelnbsp;The fructification of this plant will be considered at greater length below.nbsp;We will only observe in this place that, putting the fructification aside, thenbsp;belief that this genus belongs to Ferns is supported by the circumstance

� Schimper (1), p, 472. nbsp;nbsp;nbsp;^ de Zigno (1), vol. i, p. 151; tt. 16-18.nbsp;nbsp;nbsp;nbsp;* de Saporta (4).

Sternberg, Graf von (1), Heft 1-4, t. 20. nbsp;nbsp;nbsp;� Brongniart (5).nbsp;nbsp;nbsp;nbsp;� See above, p. 66.nbsp;nbsp;nbsp;nbsp;�� See

^bove, p, 124. nbsp;nbsp;nbsp;* See above, p. 139.nbsp;nbsp;nbsp;nbsp;� See above, p. 88.nbsp;nbsp;nbsp;nbsp;O. Feistmantel (3), t. 62.

Stur (3), p. 10; (4), p. 13. nbsp;nbsp;nbsp;Schimper (1), vol. ii, p. 129; (2), p. 227. de Saporta (H i.

that it has an extraordinary resemblance in habit to the genus Rhacopteris, Schpr, which is undoubtedly a Fern and of which we also know the fructification. In fact several species, of Rhacopteris have been placed bynbsp;authors in the genus N�ggerathia, though they differ from it in the purelynbsp;lateral insertion and in the direction of the pinnae. The literature hasnbsp;been collected by Stur It is remarkable that the two genera are foundnbsp;almost exclusively in Bohemia, Saxony, and Silesia, N�ggerathia beingnbsp;represented by several species in the Culm also of those countries. Rhacopteris Sarana^ is, I believe, the only known species from the Rhenishnbsp;Coal-measures.

Fern-FRUCTIFICATIONS. It has already been remarked that at the time that Brongniart founded his classification of fossil Ferns onnbsp;their nervation, scarcely anything was known of their fructifications.nbsp;But much has been added since that time to our knowledge of thesenbsp;organs through the labours of different observers, among whom G�ppertnbsp;Schenk*, Weiss�, and Grand� Fury� stand preeminent. It was especiallynbsp;from the examination of the silicified specimens from Grand� Croixnbsp;that the points of view were obtained, which made it possible to judgenbsp;with certainty of the remains of fructifications present only in theirnbsp;impressions. It was shown once more in the case of these objects, asnbsp;in that of the remains of Coniferae, that the direct comparison of themnbsp;with the fructifications of our recent genera is altogether precarious andnbsp;dangerous, that it is allowable only when dealing rvith remains from thenbsp;newest deposits, and then only with all proper restrictions. In this respectnbsp;also must G�ppert�s attempt at a classification of fossil Ferns, which hasnbsp;been already mentioned, be regarded as a failure. At the present momentnbsp;our knowledge of Palaeozoic and Mesozoic forms is very incomplete ; therenbsp;are a multitude of species in which the fructifications are either unknown,nbsp;or exist in a thoroughly unsatisfactory state of preservation. But this muchnbsp;has been gained, that Stur ^ by his researches, which are unparalleled fornbsp;their care and extent, has found himself in a position to lay down thenbsp;necessary principles of a rational classification of fossil Ferns ; and thoughnbsp;some of his conclusions may be open to objection and untenable, yet thenbsp;greater number of them will certainly hold their ground. A valuable publication of Zeiller�s � on this subject has also appeared almost at the samenbsp;time as Stur�s works. Unfortunately these two authors, working independently of one another, have described the. same objects under differentnbsp;names, and different objects under the same names, and thus the nomenclature has fallen into confusion. I shall adopt Stur�s nomenclature in thenbsp;following remarks, because his work covers the whole field of study more

completely than that of Zeiller; and if in these remarks I omit all mention of the Ferns of the Tertiary and Upper Cretaceous formations, which, as itnbsp;appears, are allied at all points to living species, this proceeding will notnbsp;require an elaborate justification. The gap between the Mesozoic andnbsp;succeeding forms, which is repeatedly bridged over in the case of thenbsp;Coniferae, is found to be impassable in that of the Ferns in consequencenbsp;of our almost entire ignorance of everything relating to the Jurassic types.nbsp;Hence it is that in the former case we are often compelled to unite thenbsp;Tertiary with the later forms, in the latter we are entirely exempt from thisnbsp;necessity.

First of all, Stur ^ has proved most convincingly that the Marattiaceae were much richer in species and forms, were a much more highly differentiated family, in earlier periods of the earth�s history than they are at thenbsp;present day. Grand� Eiiry ^ had already established the fact, that a largenbsp;number of the big multipinnate Pecopteridae and Sphenopteridae of thenbsp;Coal-measures belong to this family. The whole group is separated bynbsp;Stur according to certain characteristic marks into the subdivisions, Aphle-biocarpeae, Sphyropterideae, Senftenbergieae, Angiopterideae, Hawleeae,nbsp;Asterotheceae, Kaulfussieae, Danaeeae, and Marattieae, of which the Kaul-fussieae and Marattieae are living forms only, the Angiopterideae andnbsp;Danaeeae are both living and fossil, and all the rest are known only in thenbsp;fossil state. This arrangement, if we put aside the first two groups whichnbsp;appear scarcely satisfactory, may be considered to be a very happy one.nbsp;It will be convenient to commence our survey with the Asterotheceae,nbsp;because this division includes the genus Scolecopteris, Zenk., the fructification of which was long ago carefully examined in silicified specimensnbsp;from the neighbourhood of Dresden, and was distinctly recognised asnbsp;belonging to Marattiaceae �. Stur assigns to the genus Scolecopteris anbsp;number of species of Pecopteris from the Coal-measures and the Permiannbsp;formation, as for example Pecopteris polymorpha, Brongn. (Fig. 13, J?),nbsp;P. Cyathea, Brongn., P. arborescens, Schl., the fructifications of which arenbsp;also figured in Grand� Eury ^ and Renault �. We are not fully acquaintednbsp;vvith the form of the leaf in the long-known species Scolecopteris elegans,nbsp;Zenk., because we have it only in silicified fragments. The fructificationsnbsp;also of other species have been found at Grand� Croix in the silicified state.nbsp;The sori, which are roundish star-shaped on the transverse section, standnbsp;'n a single row on the back of the tertiary nerves on each side of a secondarynbsp;iierve and are formed of a small number of sporangia, and each sporangiumnbsp;has its lower half adnate to a common receptacle, which in Scolecopterisnbsp;elegans and its allies is prolonged into a distinct little .stalk bearing the

whole sorus. The sporangia are elongate-ovoid in shape with a long free upper extremity, and dehisce by a slit on the inner side; in S. Cyatheanbsp;they bulge out strongl)^ on the dorsal side and acquire a somewhat differentnbsp;shape. The wall of the sporangium is stout and of the same character allnbsp;round, and there is no indication of an annulus. If we compare this structurenbsp;of the parts of the fructification with that of our recent forms, the cohesionnbsp;of the sporangia into a roundish synangium directs us to Kaulfussia, whilenbsp;section Eupodium of Marattia supplies an exact resemblance to the elongatednbsp;stalk-like base of the receptacle ; the free extremities only of the sporangianbsp;with their long acuminations are quite peculiar to the genus. The nearestnbsp;ally of Scolecopteris, and of the group of Scolecopteris Cyathea in particular,nbsp;is Asterotheca, Presl (Fig. 13, E), which is founded on Pecopteris truncata^,nbsp;from the Coal-measures, and is still represented in later formations, asnbsp;is shown by P. Meriani which belongs to the genus and is of frequentnbsp;occurrence in the Keuper of Lunzer. The sori, which are perfectly spheroidal and are usually composed of six sporangia in close contact with onenbsp;another, are sessile and placed in a single row on each side of the mediannbsp;nerve of each pinna. The sporangia have no annulus and resemble those ofnbsp;Scolecopteris Cyathea in the bulging of the dorsal side, but they are flattenednbsp;at the top and end in a small and very short point. Owing to the firmnbsp;cohesion of the sporangia in the sorus, the dehiscence-slit cannot be certainlynbsp;perceived in the leaf-impressions, which are the only form of specimen thatnbsp;we possess, but it is probably to be found in the steep inner margin. Closelynbsp;related to Asterotheca, as Stur has convincingly shown, is Ptychocarpusnbsp;hexastichus which is Diplazites, G�pp. in Stur; but this name, since it isnbsp;based on the nervation of the fern-leaf, should not be employed. Thenbsp;sori are placed in several rows on both sides of the median nerve in eachnbsp;pinna, and are formed of a number of cohering sporangia disposed in a circle,nbsp;but they are in most cases laterally squeezed and crushed, so that in thenbsp;side-view we generally get sight of two adjacent sporangia separated fromnbsp;one another by an intervening line. Asterocarpus Sternbergii A. Merianinbsp;and Cyathocarpus eucarpus ^ may be mentioned here as older figures ofnbsp;fructifications of Asterotheca.

The genus Renaultia, Stur (Pecopteris intermedia)�, in which the shape of the lamina of the leaf is not known as our only specimens are innbsp;sections of the pebbles of Grand� Croix, deviates more widely in somenbsp;respects from Scolecopteris and Asterotheca. Renault�s drawing of the sorusnbsp;shows five sporangia disposed in a circle and opening on the inner side,nbsp;free above and adnate below to the fleshy receptacle, and distinguished bynbsp;their irregular ovoid form and occasional apical appendages, but above all

' Germar (1), t. 17. nbsp;nbsp;nbsp;� Weiss (1), t. 11. �nbsp;nbsp;nbsp;nbsp;� G�ppert (2), t, 6, IT. 1--3.nbsp;nbsp;nbsp;nbsp;* Heer (3), Trias,

t. 24. nbsp;nbsp;nbsp;� Weiss (1), tt. 9, 10.nbsp;nbsp;nbsp;nbsp;� Renault (2), vol. iii, t. 22.

by the presence in their wall of an apical group of abnormally thick-walled cells which extend some way down on the outer side of the sporangium ;nbsp;these cells have quite the appearance of an annulus, and are moreovernbsp;developed at the spot where thenbsp;rudiment of the annulus is seen tonbsp;arise in Angiopteris.

Another group is that of the Hawleeae, which differ from Astero-theceae in having free non-coherentnbsp;sporangia, but agree with them innbsp;the circular form of their sori. Thenbsp;genus Hawlea originally foundednbsp;on a small fragment of a leaf from thenbsp;Coal-measures of Svina in Bohemia,nbsp;has been enriched by Stur with manynbsp;species which appear in the oldernbsp;literature as Pecopteris, for examplenbsp;Pecopteris Miltoni, Germ., P. crenata,

Fig. 13. Fructifications of fossil Maratiiaceae from the Carboniferous formation. A Senftenbergia ophiderma-tica ; to the left the position of the sporangia on bothnbsp;sides of the median nerve of the pinnule, to the right anbsp;single sporangium seen from above. B Hawlea Miltoni;nbsp;to the left pinnae with the sori on the extremities of thenbsp;lateral nerves, to the right a single sorus more highlynbsp;magnified. C Oligocarpia lindsaeoides, showing positionnbsp;of the few-membered circular sori on the nerves of thenbsp;pinnule. ^ D Scolecopteris polymorpha, Brongn. ; to thenbsp;right a pinnule showing the position of the sori in transverse section, to the left a longitudinal section of a sorusnbsp;in which the sporangia are grown together below into anbsp;columnar receptacle. E Asterotheca Sternbergii; to thenbsp;right the pinnule with sori, to the left a side-view of anbsp;sorus and a sorus in radial section. D and E diagrain-matically represented. All the figures after Stur.

the remains described by Zeiller ^ as Calymmatotheca, which he contendsnbsp;do not belong to the genus of thatnbsp;name. The sporangia in Hawlea arenbsp;sessile and elongate-ovoid in form,nbsp;and spread out from one another innbsp;all directions, so that the dehiscence-slit on the inner side is directednbsp;straight upwards and the sporangiumnbsp;when open has the form of a boat.nbsp;The sori on the back of the tertiarynbsp;nerves form a single row on each sidenbsp;of the secondary nerve. Oligocarpia,nbsp;G�pp. (Fig. 13, C) is distinguishednbsp;from Hawlea chiefly by the characternbsp;and disposition of the sporangia ;nbsp;the two forms agree in the circularnbsp;shape and arrangement of the sori.

Grand� Eurya, Zeill. (not Stur) species of this very Saccopteris and others belonging to Desmopteris, Stur, a genus which he has figured only in the sterile state. But the figure given by Zeiller shows important points of difference,nbsp;and as I have satisfied myself of its correctness by comparing it with thenbsp;original specimens, I cannot at present acquiesce in this identification. Fornbsp;in the plants of the French author we have sori formed of erect sporangianbsp;in close contact with one another, each of which is furnished with a broadnbsp;sharply defined annulus-band running arch-wise across the apex, which Sturnbsp;indeed explains as due to the state of preservation. These characters, asnbsp;the author ^ himself points out, remind us to some extent of the group ofnbsp;Botryopterideae, which will be considered presently. But when the twonbsp;remains of fructification, to all appearance so unlike one another, are unitednbsp;by their authors with the same fern-leaves, with Sphenopteris Essinghii,nbsp;Andr. and S. coralloides, Gutb. Gein., or S., erosa, Gutb. Gein., it maynbsp;be remarked that sterile leaf-forms very like one another belong to differentnbsp;genera, and lastly that the fertile leaves of the Ferns in question differ considerably from the sterile, and that this must render their determinationnbsp;difficult. For the details of this controversy, on which fresh light is needed,nbsp;the reader should consult the original publications, and especially Zeiller�s ^nbsp;reply to Stur.

Corda�s ^ genus Senftenbergia (Fig. 13, A), which has been submitted by Stur^ to a fresh and searching examination, is the type of the Senften-bergieae. The plants of this group also are by their nervation Pecopteridaenbsp;and Sphenopteridae; among them for example are Pecopteris aspera,Brongn.,nbsp;P. plumosa. Art., Sphenopteris crenata, Ldl. and Hutt., and others from thenbsp;Coal-measures. Of the Triassic fern-fructifications enumerated by Stur�nbsp;there are none belonging to this group. The free sporangia are not collected into sori but are found one by one on the back of the tertiary nerves,nbsp;forming a longitudinal row on each side of the secondary nerve. Eachnbsp;Sporangium in the typical Senftenbergia elegans is obliquely conical andnbsp;acuminate from a rounded base, and turns the gentler curve, on which isnbsp;the dehiscence-slit, towards the outside. On its stout wall at the conicalnbsp;apex may be seen a hood-shaped annulus, which is formed of several circularnbsp;�quot;ows of cells lying one on another, and according to Stur is not distinctlynbsp;defined below. Corda� and after him Renault^ and Zeiller� represent thisnbsp;annulus in their drawings with a much sharper boundary-line below, andnbsp;^ake it the ground for putting the genus among Schizaeaceae. Stur rightlynbsp;objects to this that in Schizaeaceae the strongly individualised annulus isnbsp;all cases formed of a single circular row of cells, and attaches great weightnbsp;1^0 the fact that the rudimentary annulus of Senftenbergia is easy to connect

,, ( Zeiller (6), p. 205. nbsp;nbsp;nbsp;quot; Zeiller (B).nbsp;nbsp;nbsp;nbsp;= Corda (1), t. 57.nbsp;nbsp;nbsp;nbsp;� Stur (5, 4,3).nbsp;nbsp;nbsp;nbsp;= Stur (7;.

^'orda (1', nbsp;nbsp;nbsp;� Renault (2), vol. iii, t. 12, ff. 7, 8.nbsp;nbsp;nbsp;nbsp;� Zeiller (7), t. ic. ff. 1-5.

in number, they form a simple circle and are laterally in contact with one another; when there are more of them, as in Oligocarpia Brongniartii, wenbsp;find a central group of two or three sporangia surrounded by a simplenbsp;outer circle. They are attached to the expanded receptacle by a broadnbsp;flat basal surface ; they are obliquely pyramidal in shape and incline towardsnbsp;one another and towards the middle of the sorus. Stur is of opinion thatnbsp;the place of dehiscence may be seen in the form of a pore at the obtusenbsp;apex ; at all events a gaping lateral slit has never been observed in any ofnbsp;the numerous specimens which have been examined. The stout wall, atnbsp;least in the upper pyramid-shaped portion, is formed of large polygonalnbsp;very thick-walled cells, which are developed however in a similar mannernbsp;all round, so that no proper annulus can be distinguished. G�ppert hadnbsp;already credited his Oligocarpia Gutbieri with a well-developed annulus,nbsp;which he compared with that of Polypodiae ; Zeiller subsequently reaffirmed its existence and described it as an �annulus transversal is,� and thusnbsp;the genus came to be placed among Gleicheniaceae. By the kindness ofnbsp;the latter author I have had the opportunity of seeing his specimens, and Inbsp;am still obliged to assent to Stur�s denial of the independent existence ofnbsp;this annulus. If we look at the obliquely conical sporangium from above, wenbsp;get a profile view of one or more transverse rows of the strongly thickenednbsp;cell-walls, and may mistake them for an annulus; but we find that whenever we alter the position of a detached sporangium, the supposed annulusnbsp;appears in another place. Stur is right in his remark that Zeiller�s figuresnbsp;do in fact show this, and that the ring appears in them in a different positionnbsp;according as the sporangia are seen from above, or in the side-view.

Stur�s account of his genera Discopteris and Saccopteris, which he would refer to this place, is not so convincing as that of Hawlea andnbsp;Oligocarpia. Discopteris, which includes various Sphenopteridae, amp;c., fromnbsp;the Coal-measures, as Sphenopteris Goldenbergii, Andrae, S. Coemansi,nbsp;Andrae, has round sori formed of a large number of sporangia (70-100).nbsp;The sporangia are very small and have a � superficies reticulato-areolata.�nbsp;Zeiller^ compares his Myriotheca with Discopteris; but in Myriotheca,nbsp;according to the description, the free ovoid sporangia which resemble thosenbsp;of Marattiaceae cover the whole under surface of the leaf without formingnbsp;distinct sori, somewhat after the manner of Acrostichum. Saccopteris,nbsp;Stur, is composed of forms from the Coal-measures, which by their nervation belong to Pecopteris, Alethopteris, and Sphenopteris. Its sori, placednbsp;in two rows on the pinnae, are circular in shape and are formed of numerousnbsp;irregularly disposed elliptical sporangia, which are attached by a narrownbsp;base and open on the inner side towards the apex by a pore with a steepnbsp;border. Stur endeavours to show that Zeiller has described under the name

with others of the kind, such as are found in the series of Marattiaceae. Again, Stur unites the genus Dactylotheca ^ and also Pecopteris exiguanbsp;known only from the siliceous fragments of Grand� Croix, to Corda�s genus,nbsp;while Zeiller �� protests warmly against this proceeding. In both certainlynbsp;the sporangia are isolated, as in Senftenbergia, but fresh researches may benbsp;required to clear up their differences. Lastly, to come back once more tonbsp;the disputed question of placing our genus with Marattiaceae, it is clearnbsp;that we must extend the characters of this family considerably before wenbsp;can introduce into it forms with so highly developed an annulus as Renaultianbsp;and Senftenbergia; still this would be a wiser course, considering othernbsp;points of connection which exist between these Ferns and forms which undoubtedly belong to Marattiaceae, than to found new families upon them,nbsp;or to thrust them not without violence into others that are already established. There may possibly be intermediate forms ready to our hand,nbsp;which would actually fill the gap between the exannulate Marattiaceae andnbsp;various annulate groups, and in that case we might think of Senftenbergianbsp;in connection with Schizaeaceae and of Renaultia with Osmundaceae. Fornbsp;we cannot with Stur so entirely put aside the resemblance between thenbsp;sporangium of Senftenbei'gia and that of Schizaeae, when Bunbury^ also,nbsp;describing the fructification of Pecopteris exilis, Phill. from the Oolite ofnbsp;Scarborough, says in reference to its likeness to Corda�s Senftenbergia thatnbsp;it is distinguished from it only by the circumstance that its apical annulusnbsp;consists of a single row of cells. We should thus have a genuine membernbsp;of the family of Schizaeaceae from deposits which are at any rate fairly old.nbsp;A re-examination of the original specimen would be very desirable. Asnbsp;regards Stur�s� genera Sphyropteris and Hapalopteris, of whose connectionnbsp;with Senftenbergia I am not fully convinced from the author�s statements,nbsp;it will be sufficient to refer the reader to the original publications. In conclusion, Sarcopteris Bertrandi � should be noticed here, a species known tonbsp;us only in a few transverse sections of fragments of fertile leaves from thenbsp;pebbles of Grand� Croix. The spherical thick-walled sporangia stand singly,nbsp;and not grouped in sori, on the lower surface of the very thick lamina, andnbsp;show on one side a large-celled irregularly defined tissue marking the positionnbsp;of an annulus and reminding us of Stur�s Renaultia.

The Angiopterideae, which are characterised, as is well known, by free sporangia uniting to form sori with a distinct configuration, are considerednbsp;by Stur to include only two forms, the remains of which were obtained bynbsp;Renault � from the pebbles of Grand� Croix and placed in the genusnbsp;Pecopteris. These species are named by Stur Grand� Eurya Renaulti and

� Zeiller (7), t. g. * Renault (2), vol. ill, t. 19, ff. i.?-i8. nbsp;nbsp;nbsp;* Zeiller (6).

p. 188 ; t. 13, f. nbsp;nbsp;nbsp;�� Stur (3) and (4).nbsp;nbsp;nbsp;nbsp;* Renault (2), vol. iii, t. 21, ff. 12-15.

G. Autunensis, and with our present knowledge of them they would certainly appear to belong to the type of Angiopterideae; the sori, which are formednbsp;of a large number of sporangia, are elliptical, and are developed on thenbsp;back of the tertiary nerves. Renault�s drawings of the sporangia show nonbsp;rudiment of an annulus. According to Schenk^ the genus Angiopteridium*'*,nbsp;founded on Taeniopteris Miinsteri � from the Rhaetic beds, also belongs tonbsp;this group. The fructification which he has figured does in fact show thenbsp;very greatest likeness to that of our recent Angiopteris. Schenk states distinctly that the sporangia of Angiopteridium, like those of Angiopteris, donbsp;not cohere; the figures it is true are not decisive on this point. Since wenbsp;have to depend entirely on impressions of the plant, we cannot obtainnbsp;absolute certainty on this question ; and if it is proved that the sporangianbsp;are coherent, the genus must be moved nearer to Marattia, which Schimper^nbsp;thinks is its proper place.

With Danaeaceae Stur places the genus Danaeites�, which was originally founded on a Pecopteris from the Coal-measures with a more than doubtful fructification, and was afterwards somewhat more certainly determined by him with the help of fresh specimens. The tertiary nervesnbsp;of Danaeites saraepontanus, Stur, like those of Danaea, bear linear sorinbsp;parallel to and touching one another and composed of numerous sporangianbsp;in two rows; but the boundary-lines of the cohering sporangia can be distinguished in the surface-view, which is not the case in the living genus.nbsp;Stur even maintains that he has observed indications of the characteristicnbsp;membranous indusial cup on pinnae from which the sori have fallen off; henbsp;has not been able to determine the mode of dehiscence. Another apparentlynbsp;allied form is Danaeites Heeri � from the Lias of Upper Italy. The leavesnbsp;of this species show the nervation of Taeniopteris, and bear sori which havenbsp;quite the habit of those of Danaea. Unfortunately we know only the external form; the figure also is perhaps rather too roughly sketched, as itnbsp;does not show the isolated round dehiscence-spots on the sporangia mentioned in the diagnosis. Whether this is the case, or whether the diagnosisnbsp;says too much, can only be decided by inspection of the original specimens.nbsp;Further investigation is also required in order to determine how far Danae-opsis (Taeniopteris) marantacea. Heer, the fructification of which is figurednbsp;in Schimper^, belongs to the above forms. The sori of this handsome fern,nbsp;''^hich is peculiar to the Keuper coal-beds, agree very fairly in habit withnbsp;those of Danaea. They too appear, according to Schimper�s drawings, tonbsp;dehisce by dot-like pores; but it is still a question whether they cohere, asnbsp;m Danaea, or not.

well to notice the small group of Botryopterideae, with which Renault�s ^ excellent investigations have made us tolerably well acquainted. Collectionsnbsp;of fragments of fruiting leaves of these plants are occasionally found in thenbsp;pebbles of Grand� Croix and Autun, from thin sections of which we learnnbsp;that the leaf had no normal lamina, but that crowded and irregularlynbsp;branched bunches of stalked sporangia formed the final terminations ofnbsp;a branched and regularly pinnated leaf. The sporangia themselves arenbsp;ovoid (Botryopteris), or elongate-ovoid and slightly curved (Zygopteris),nbsp;and had stout walls, but the mode of dehiscence is not stated. The wall isnbsp;formed of one layer of cells according to Renault, but Grand� Eury^, whonbsp;has also figured this or a similar form, depicts several cell-layers. It maynbsp;be conjectured that the inner layers were destroyed in Renault�s specimens,nbsp;and his figures show a sac-like envelope inclosing the spores, which I cannbsp;only suppose to be a crushed cell-layer. Both genera show an annulus,nbsp;which if not sharply defined is still evident. In Zygopteris the annulusnbsp;forms two longitudinal bands running from top to bottom, which unitenbsp;perhaps above the apex, and which can be distinctly perceived to the rightnbsp;and left on the transverse section as large-celled parietal tissue. Its shapenbsp;reminds us to some extent of Grand� Eurya, Zeill. (not Stur), which wasnbsp;described above. In Botryopteris the annulus is on one side and less distinct, and is more like that of Renaultia, Stur, except that it does not extendnbsp;to the apex of the sporangium. Renault � thinks it is � rather a disk analogous to that of Todea or Osmunda, only more developed and differentlynbsp;disposed.�

It was stated above that Grand� Eury^ had already compared these bunches of sporangia known to him from Autun with certain impressions from St. Etienne which he names Androstachys, but which had beennbsp;previously found near Wettin and described by Germar� as Araucaritesnbsp;spiciformis, and indeed had explained them both as male organs of plantsnbsp;resembling N�ggerathia. We do in fact find in this Androstachys ofnbsp;Grand� Eury the same little clusters of organs as those just described, andnbsp;they are ranged on both sides of the thick rib-like bladeless primary raysnbsp;of a regularly pinnated leaf. It can scarcely be doubted therefore thatnbsp;they belong to one another. And lastly. Grand� Eury succeeded in findingnbsp;sterile leaves also with the same habit, in which the bunches of sporangia arenbsp;simply replaced by delicate and apparently in-egularly divided portions ofnbsp;the lamina, in which the nervation could not be determined, though it wasnbsp;supposed to be that of Caenopteris. These sterile leaves, to which Grand�nbsp;Eury gave the name Schizopteris pinnata, have been claimed by Renault asnbsp;belonging to Zygopteris, and it appears to me extremely probable that the

' Renavilt (4) and (5). nbsp;nbsp;nbsp;* Grand� Eury (1), t. 17.nbsp;nbsp;nbsp;nbsp;� Renault ' 4).nbsp;nbsp;nbsp;nbsp;' Grand� Eury (1), t. i7-

two do belong to one another. From the knowledge which we possess of the leaf-stalks and stems of Botryopterideae, and which also we owe tonbsp;Renault, it seems tolerably certain that the group consisted of delicatenbsp;herbaceous Ferns. We shall have to return to them further on in order tonbsp;consider the anatomical details of their structure.

The genera Rhacopteris and N�ggerathia, the barren leaves of which have already been discussed at some length, are both known also in thenbsp;fertile form. Stur is perhaps right in placing them in the family of Ophio-glossaceae on account of their fructifications, but this relationship will notnbsp;be satisfactorily established for the botanist, until the remains have beennbsp;found as petrifactions and with their structure preserved. The only leafnbsp;of Rhacopteris paniculifera ^ hitherto discovered has normal sterile pinnaenbsp;below; the main axis forks repeatedly at its upper end and forms a loosenbsp;tuft of small branches, the extremities of which are surrounded by crushednbsp;and for the most part detached sporangia. These sporangia are small andnbsp;globular, and on one of them Stur believes that he has seen a fissure. Fie isnbsp;led to refer this fossil to Ophioglossaceae and to compare it with Botrychiumnbsp;chiefly from the development of a fertile and a sterile portion of the laminanbsp;in the same leaf, and because he could perceive no annulus on the crushednbsp;sporangia. This reference therefore is obviously very precarious, for annbsp;analogous behaviour is observed in the fertile leaves of very various Ferns,nbsp;and as regards the terminal position of the fertile leaf-segment there is nonbsp;really serviceable object of comparison to be found in Ophioglossaceae. Anbsp;similar state of things to that which occurs in Rhacopteris is also observednbsp;according to Schimper^ in Triphyllopteris Collumbi, Schpr., from the Culmnbsp;of Thann ; but here we have no certain ground to go upon owing to thenbsp;indifferent preservation of the specimen, and moreover it does not appearnbsp;from the text whether there is any proof of the connection between thenbsp;sterile and fertile portions figured, or whether this connection is concludednbsp;merely from their occurring together in the strata.

Essentially similar objections may also be raised respecting the genus N�ggerathia ^ Its fructification, clearly ascertained from the circumstancenbsp;that the lowermost pinnate leaves are sometimes sterile and also shownbsp;the characteristic features of N�ggerathia foliosa, was first described bynbsp;Geinitz and was declared to be of gymnospermous origin. Further lightnbsp;was afterwards thrown on the question, and by no one more than by K.nbsp;FeistmantelThe literature of the subject has been collected by Stur''.nbsp;By the close approximation of the pinnules to one another the fertile leavesnbsp;or leaf-segments assume the appearance of dense spikes ; the pinnae themselves change their form and become broad scales with the anterior margin

the annulus, which is distinctly formed in each case, would afford an excellent means of distinguishing them. It is true that Williamson \ for example, and Carruthers ^ have figured a good many sporangia in sectionsnbsp;from English calcareous nodules, which they consider to belong to Gleiche-niaceae or Hymenophylleae. I possess a variety of sections through thesenbsp;sporangia in which at first sight we fancy that we see an evident circularnbsp;annulus. But if we happen to light upon a surface-view of these objects, wenbsp;see that the wall is everywhere of the same structure, and that every sectionnbsp;therefore in whatever direction it is made would show an illusory annulusnbsp;transversalis; there is nothing therefore which compels us to regard themnbsp;as anything else but sporangia of Marattiaceae, especially when we knownbsp;how generally the latter are distributed through the groups of the Palaeozoicnbsp;formations. The best-known example from the Coal-measures is certainlynbsp;the fern-leaf figured by Zeiller � as Hymenophyllites delicatulus, Stbg.nbsp;Here there does really seem to be a transversal annulus, as appearsnbsp;especially from the side-views given in Zeiller�s figures It is true thatnbsp;I have never myself seen sporangia in this position in the original specimens,nbsp;which the author demonstrated to me in the kindest manner, probablynbsp;because the shortness of the time at my command did not admit of anbsp;thorough study of the slab ; but I carried away with me the generalnbsp;impression that the facts had been correctly interpreted and that no othernbsp;explanation of the pictures was possible. We need not indeed go into thenbsp;question whether we are justified in calling the leaf Hymenophyllites ; it isnbsp;in favour of this determination that the sporangia which are no longer mnbsp;situ lie in groups in front of the extremities of the nerves of the tip of thenbsp;leaf; there is no trace of the characteristic thorn-shaped placenta or of thenbsp;cup-shaped indusium. Another form described as of the same group,nbsp;Hymenophyllum Weissii� from Saarbr�cken, is to my mind more thannbsp;doubtful; its sporangia are unknown, and I have been unable to satisfynbsp;myself from the specimens in the Museum at Strassburg that the characternbsp;of the sori is as described by the author. Heyer'' also, who had thenbsp;specimens in the Goldenberg collection before him, was not more successful than myself. The same remark applies also to Hymenophyllitesnbsp;Humboldti, G�pp., and Trichomanites Beinerti as well as to the genusnbsp;Palaeopteris, of which Schimper figures the fruiting heteromorphous leaf-segments In these also the structural details of the fructifications, whichnbsp;are declared by the author to be two-lobed indusia, cannot be certainlynbsp;determined.

dentate, and overlap and quite conceal the rhachis. These pinnae bear the sporangia, which are present in large numbers and are attached to the uppernbsp;surface. That these small ovoid bodies cannot be seeds of a gymnospermnbsp;is proved by K. Feistmantel�s discovery of numerous spores inside them.nbsp;No annulus has been observed in their wall, which is formed of severalnbsp;layers of cells. Taking all this into consideration, we may agree withnbsp;Stur, who will not hear of a comparison with Cycadeae or Coniferae. Onnbsp;the other hand, the botanist, when he looks at the figures, will not see toonbsp;many or too obvious points of resemblance to Botrychium or Helmin-thostachys.

Under the name of Aphlebiocarpus Sch�tzei Stur ^ has described a remarkable but unfortunately very imperfect fructification, which mustnbsp;without doubt have belonged to a fern. A piece of a repeatedly branchednbsp;leaf-axis bears at the extremity of the branches stellately-lobed foliar formations, which are attached by their central point and have here and therenbsp;on their surface small protuberant insertion-points. The lobes incliningnbsp;towards one another from the first like the leaves of an involucre, enclosednbsp;a number of sporangia, as is seen in other specimens ; these sporangia according to Stur were ovoid and without an annulus, and resembled those ofnbsp;Senftenbergia. But when Stur attempts to found a formal history of development on these facts, and makes these formations be at first open andnbsp;then close up to form a capsule and develope sporangia, he is pursuing anbsp;path on which I cannot follow him. As little can I accept his reasons fornbsp;considering that the genus in question belongs to Marattiaceae, and fornbsp;establishing a special sub-group, Aphlebiocarpeae, to receive it. Thenbsp;farthest that we can go in this matter, is to admit the proof that thenbsp;sporangium is like that of Senftenbergia; for Stur�s favourite comparisonnbsp;of the stellately-lobed envelope with Aphlebiae, even if proved or onlynbsp;made very probable, which is not the case, would still be far from supporting the view that the fructification in question belongs to Marattiaceae,nbsp;since such a conclusion, as was shown above, is based on the decidedlynbsp;erroneous supposition, that the Aphlebiae are peculiar to this family andnbsp;homologous with their stipular formations. We will hope that furthernbsp;discoveries may throw more light on the structure of this remarkablenbsp;fossil.

If, as the foregoing remarks have endeavoured to show, we are able to recognise with more or less certainty a fair number of genera of Euspo-rangiate Filicineae, our success in determining the Leptosporangiate formsnbsp;has been much more limited. As far as I know, scarcely a single specimennbsp;of the latter kind above suspicion has been obtained from the Coal-measures ;nbsp;this is the more remarkable because we might think that the characters of

Leptosporanglate Ferns during the periods of the Coal-measures, we know on the other hand from Schenk�s ^ researches that there were a considerablenbsp;number of them already in being while the Rhaetic beds were in processnbsp;of deposition, and that they are to be assigned to the genera Laccopteris,nbsp;Presl, Selenocarpus, Schenk, Andriania, F. Braun, Clathropteris, Brongn.,nbsp;Dictyophyllum, Lindl. and Hutt., and Thaumatopteris, G�pp. The sorinbsp;of all these ferns are composed of a few large sporangia, and in this respectnbsp;they agree with Gleicheniaceae; but each sporangium has a closed obliquenbsp;and unusually well-marked annulus, quite in the manner of Cyatheaceae.nbsp;This was fully proved at first by Schenk and it has recently been positively confirmed by Zeiller � in the case of Laccopteris. Schenk hasnbsp;already called attention to the agreement between these characters andnbsp;tho.se of the Malayan genus Matonia, which standing as it does quite alonenbsp;in our present vegetation and in an intermediate position between Cyatheaceae and Gleicheniaceae evidently represents an ancient type now in coursenbsp;of extinction; and Zeiller has shown the perfect identity of the sori ofnbsp;Matonia and Laccopteris by placing figures of them side by side. Thenbsp;great variety in the character of the lamina of the leaf in all these fernsnbsp;shows plainly how very dangerous it is to make use of this part of the plantnbsp;for the purposes of rational classification. Osmundaceae also seem to occurnbsp;as early as the Jurassic period. To this group belongs Alethopterisnbsp;australis, Morris, from Queensland, according to Renault^. Its ovoidnbsp;sporangia are in longitudinal rows along the course of the secondary nervesnbsp;of the pinnules, and are furnished on one side with a � plaque de d�hiscence.�nbsp;Pecopteris Williamsonis, Brongn., from the Oolite of Scarborough is alsonbsp;placed by Schenk� with Osmundaceae, and named in accordance with thisnbsp;position Todea Williamsonis. A figure of the plant is to be seen in Lindleynbsp;and Hutton �. Schenk gives a good description of its sporangia and of thenbsp;spores which they contain.

It remains only to mention the fern-fructifications in which we know the external characters only and little or nothing of the sporangia ; thenbsp;position of such forms in the system cannot be determined with any degreenbsp;of certainty, except when they come from Tertiary formations and havenbsp;some claim to be connected with living species.

The genus Calymmotheca, Stur appears to occur in many parts of the Coal-measures, and to be represented there by numerous species. It wasnbsp;first observed by Schimper in the Culm of the Vosges, and thoroughlynbsp;examined and established by Stur ; and the attempt I'ecently madenbsp;by Kidston * to separate a new genus Zeilleria from this group must in

= Schenk (11), p. i68; t. 15, ff. 3a, 31^. (3, 4, h, 6).nbsp;nbsp;nbsp;nbsp;� Kidston (1).

the present state of our knowledge be regarded as premature. Stur has included a large number of Sphenopteridae in his genus Calymmotheca;nbsp;these all agree in the circumstance that their fertile leaf-segments terminatenbsp;in peculiar capsule-like indusia formed of several lobes, which close uponnbsp;one another like valves and ultimately expand and assume the form of a starnbsp;or almost of a corolla. These indusia show a remarkable variety of dimensions, and in some species from the Culm especially they reach a very considerable size. The details of their form also vary much ; the valves on thenbsp;median line of the dorsal surface in Calymmotheca Stangeri, Stur, are coverednbsp;with thorn-like projections. Stur has done well to bring genera like Sphae-ropteris. Wall, and Diacalpe, Bl. from among recent Ferns into comparisonnbsp;with Calymmotheca, and Cyathea Brunonis, Wall, might be added to them ;nbsp;if the laminae of the leaves disappear from Sphaeropteris barbata. Wall.,nbsp;and the nerves only are left with the thick-walled stalked sori, a form likenbsp;Calymmotheca would in fact be produced. But this comparison, serviceablenbsp;as it is in some respects, tells us nothing about the affinity of our forms, nornbsp;shall we be able to determine that point until we succeed in discovering thenbsp;altogether unknown sporangia. Stur himself, who inclines to place themnbsp;with Cyatheaceae, fully recognises the precarious nature of this disposition.nbsp;From Calymmotheca Stur next proceeds to the consideration of his genusnbsp;Sorotheca, in which the fruiting terminal pinnae are flattened out andnbsp;thickened, and are encircled with numerous narrowly lanceolate indusialnbsp;valves. The points of insertion of the sporangia can be seen as small scarsnbsp;on the surface of the pinnae. At first the valves of the indusium are con-nivent, but they subsequently expand in a stellate manner. Zeiller ^ indeed,nbsp;who has described the same plant from the Belgian coal-fields as Crosso-theca Cr�pini, explains the parts of the fructification in a totally differentnbsp;manner, since he takes the lanceolate projections, Stur�s indusial valves, fornbsp;the sporangia themselves. In that case the scars observed by Stur, whichnbsp;Zeiller^ in his rejoinder to Stur rather passes over, would not be easy tonbsp;understand. Lesquereux ^ has figured some fructifications which look likenbsp;these of Sorotheca, but whether they should be placed with that genus ornbsp;with Calymmotheca is a point which cannot be determined from the somewhat imperfect account given of them. The American author has namednbsp;these objects Staphylopteris, Lesq. (S. Wortheni, S. asteroides, S. stellata),nbsp;but he also includes in his genus various other forms, such as S. sagittatus,nbsp;Lesq., which evidently have nothing whatever to do with it, as has beennbsp;already pointed out by Schimper^.

The doubts, which are shared by Stur himself, as was before said, respecting the relationship of the genera Calymmotheca and Sorotheca to

Zeiller (C). nbsp;nbsp;nbsp;^ Lesquereux vol. iv, p. 405; t. 14, and (4), p. 310;

Cyatheaceae, are with him founded chiefly on the analogies which seem to exist between his genera and a fossil form hitherto of very doubtful nature,nbsp;which Corda^ described as Chorionopteris gleichenioides, and withoutnbsp;any apparent reason referred to Gleicheniaceae. This object is a diminutivenbsp;fragment of a fruiting fern-leaf from the Coal-measures of Radnitz innbsp;Bohemia; it is found in the silicified beds of Millstone grit in thatnbsp;locality, and shows the structure when the sections are examined in directnbsp;light. A thin axis bears several closed capsules about a millimetre innbsp;diameter, which are formed of several layers of cells and are of a solidnbsp;character. Each capsule opens by four valves and contains four sporangianbsp;filled with spores. There is no indication of an annulus on the thin wall ofnbsp;the sporangia, and their points of attachment are not clearly shown. If wenbsp;adopt Stur�s very natural comparison of this many-lobed indusial capsulenbsp;with that of Calymmotheca, yet the structure of the sporangia wouldnbsp;scarcely suggest any close affinity with Cyatheaceae.

Stur founded his genus Diplotmema, as has been already shown, merely on the form and mode of branching of the lamina of the leaf, andnbsp;compared it with the recent genus Rhipidopteris. Points of attachment ofnbsp;the fructifications are of rare occurrence on the leaves, and in Diplotmemanbsp;Zwickauiense, Gutb., the one species in which they appear, they are foundnbsp;on the terminations of the tertiary nerves, which emerging from the surfacenbsp;of the leaf within the margin form in a peculiar way a small disk-like andnbsp;toothed expansion. On this structure the unknown sporangia are supposednbsp;by Stur to have been seated, which is possible but is certainly not provednbsp;The same author� had previously given a different description of thenbsp;fructification of D. geniculatum, and placed it in the bifurcation of the leafstalk, where he still keeps it. With other authors, Zeiller for example, I amnbsp;disposed to see in these objects simply buds, such as those which shootnbsp;forth so abundantly in the forks of the leaves of Gleicheniaceae.

A number of fossil remains have been directly united with the recent monotypic genus Thyrsopteris, Kze, which lives in the Island of Juannbsp;F'ernandez and was placed by Mettenius with Cyatheaceae, solely onnbsp;account of their appearance and of the character of the receptacles whichnbsp;contain the fructifications, the sporangia being unknown. Heer*, relying onnbsp;several fossil forms from the Oolitic strata of Siberia, is especially earnest innbsp;his support of this classification. His descriptions apply most exactly tonbsp;Thyrsopteris Murrayana, whose fertile pinnate leaves have no lamina, andnbsp;are covered with stalked cup-shaped involucres concealing the sori. Th.nbsp;Maakiana is a similar form; a fossil known as Th. gracilis. Heer, seems tonbsp;me very doubtful. Th. Murrayana is also found in the Oolitic beds of

Scarborough ; when it was first found it was taken for an alga and named Tympanophora^; it was subsequently recognised by Williamson^ as thefructi-fication of a fern, Pecopteris Murrayana. This view has since been workednbsp;out by Bunbury� and Leckenby^ and illustrated by figures. Saporta� hasnbsp;retained the name Coniopteris given by Brongniart for this fructification innbsp;spite of its great resemblance to our living Thyrsopteris ; and this course isnbsp;in my opinion worthy of imitation, because it shows caution. If Thyrsopteris schistorum � from the roofing-slates of the Culm of Moravia andnbsp;Silesia really belongs to this genus, which from the habit does certainlynbsp;appear to be the case, this would be a very ancient type; but on this pointnbsp;Stur himself speaks with all reserve.

Several fern-leaves from the Jurassic system are placed by Heer^ in the genera Dicksonia and Asplenium solely on account of the habit of thenbsp;sori as preserved in impressions ; thus we have Dicksonia Saportana, Heernbsp;(Scleropteris, Sap.), and Asplenium spectabile. Heer, and A. Whitbyensenbsp;(Cladophlebis, Auct.). It is no longer necessary to insist at length on thenbsp;precariousness of this determination. Lastly must be mentioned the genusnbsp;Stachypteris, Pomel, from the Coralline Oolite of Verdun, in which bipinnatenbsp;leaves resembling those of Cheilanthes show segments of the third order ofnbsp;abnormal and peculiar form, the supposed fertile pinnules. Its discoverernbsp;Pomel compared it with Lygodium ; Saporta * does not assent to this, andnbsp;would refer it rather to Onychium.

Inner Leaf-structure, Rhaghiopteridae and P'ern-stems. In connection with the above account of the leaves of fossil Ferns and of thenbsp;fructifications which they bear we may now proceed to consider certainnbsp;anatomical peculiarities such as are described in the works of Williamson� and Renault^�, and which are disclosed by sections of the laminaenbsp;of petrified leaves. In general it appears that the structure of fern-leaves in the period of the Coal-measures was essentially the same asnbsp;that of recent species, being as a rule distinctly bifacial with several layersnbsp;of palisade-cells on the upper and spongy parenchyma on the under side.nbsp;The nerves also, which often project strongly on the back of the leaf, arenbsp;formed in the normal manner either of one strand of vascular bundles, or ofnbsp;several variously fashioned and concentric strands. Tissues also withnbsp;mechanical function are often present in the form of strips of sclerenchymanbsp;beneath the epidermis of the upper side of the leaf, often with localnbsp;strengthening ribs like bands, as in Pecopteris Geriensis 1^. In other cases,nbsp;as in the Alethopteris figured by Renault the subepidermal strips of

' Lindley and Hutton (1), vol. iii, 1.170. nbsp;nbsp;nbsp;^ Brongniart (2).nbsp;nbsp;nbsp;nbsp;� Bunbury (1).nbsp;nbsp;nbsp;nbsp;* Leckenby (-1).

* de Saporta (4). nbsp;nbsp;nbsp;� Stur (6) and (4).nbsp;nbsp;nbsp;nbsp;� Heer (5), vol. 4 ii, t. 2, ff. 16-18 and 21.nbsp;nbsp;nbsp;nbsp;quot; de

Saporta (4), vol. i, p. 379 ; t. 49. nbsp;nbsp;nbsp;� Williamson (1), VI, vni.nbsp;nbsp;nbsp;nbsp;Renault (2).

very peculiar form, and in these points they agree exactly with the axes of recent fern-leaves. There are also in very many cases longitudinal sub-epidermal regularly disposed bands of sclerenchyma, which extend more ornbsp;less far into the parenchyma. Corda \ to whom we are indebted for thenbsp;first examination into the anatomical details of these remains, has dividednbsp;them into numerous genera founded essentially on the form and position ofnbsp;the concentric bundles of the wood. Later authors, with a more superficialnbsp;treatment of the subject, have on the whole adopted Corda�s terminology,nbsp;though Brongniart ^ carefully insisted that this distribution was quite provisional, since an axis of a lower order of branching often differs in structurenbsp;from the main axis in the same species, and that the two would therefore innbsp;Corda�s system be placed in different genera. This restriction has ultimatelynbsp;been applied in practice by Williamson who has included by far the largernbsp;number of these bits of leaf-stalk in the genus Rhachiopteris, rightly keepingnbsp;a few only separate from the rest, because they are distinguished by specialnbsp;peculiarities of structure in thick and thin pieces alike. The leaf-stalksnbsp;occur in very many cases as isolated detached fragments, especially in thenbsp;often-mentioned calcareous nodules of the Coal-measures and in thenbsp;siliceous pebbles of Grand� Croix; but they have sometimes been found innbsp;thick bundles interwoven with numerous roots, a state of preservation tonbsp;which Corda has given the generic name of Tempskya, but which is sometimes also termed Endogenites, Spreng., though this appellation belongsnbsp;particularly to the wood of palms. It is obvious then that this genus cannot be maintained as it is, but it may be conveniently employed as a generalnbsp;term for this particular state of preservation, so that Zygopteris for examplenbsp;would be known both in the free state and in the Tempskya-condition.nbsp;We may observe here briefly that the adventitious roots of Temskyaenbsp;which are interwoven with the leaf-stalks show thoroughly the normal fern-structure with a central radial usually pentarc or hexarc vascular bundle.

We now proceed to notice the most important of Corda�sgenera, all of which come from the Coal-measures of Bohemia. The transverse sectionsnbsp;of Selenopteris �, Anachoropteris and Gyropterisshow a single bundle,nbsp;which in the last genus is coiled, in the first is crescent-shaped, and innbsp;Anachoropteris is in the shape of a horse-shoe with involute extremities.nbsp;Next comes Selenochlaena I'esembling Selenopteris and founded on Cotta�s�nbsp;Tubicaulis dubius and Solenites, and Zygopteris founded on his Tubicaulisnbsp;primarius. In the latter form, of which through Renault�s� researches wenbsp;know the stems and fructification, the bundle has somewhat the shape of anbsp;Latin H. Finally, in Kalopteris besides the crescent-shaped bundle of

' Coida (1). nbsp;nbsp;nbsp;� Brongniart (2), p. 85.nbsp;nbsp;nbsp;nbsp;� Williamson (1), vi. * Corda (1).nbsp;nbsp;nbsp;nbsp;� Corda

ik, tt. 53, 54. nbsp;nbsp;nbsp;� Corda (1), tt. 56, 57.'nbsp;nbsp;nbsp;nbsp;' Corda (1), t. 34.nbsp;nbsp;nbsp;nbsp;� Cotta (1).nbsp;nbsp;nbsp;nbsp;� Renault (5).

tissue are wanting, and in place of them we have the well-known T-shaped trabeculae very perfectly developed traversing the lamina of the leaf andnbsp;enclosing the bundle-sheath. We have already observed the like arrangement of the mechanical system in Cordaiteae, and shall meet with it againnbsp;further on in very many cases. In further exemplification of this subjectnbsp;may be mentioned the figures given by Williamson ^ of the leaf-structure ofnbsp;his Rhachiopteris aspera. I have satisfied myself with regard to the factsnbsp;in the case of both these ferns from various preparations in my possession.nbsp;In Pecopteris densifolia, Ren. andP. exigua^, there appear to be no mechanicalnbsp;elements in the surface of the leaf, and none in Sarcopteris Bertrandinbsp;Well-preserved hairs, either detached or still in situ, have been observed notnbsp;unfrequently in specimens from the pebbles of Grand� Croix. In one leaf-fragment of a Pecopteris the substance of the under side of the leaf swellsnbsp;up between the tertiary nerves, and forms receptacles like deep channelsnbsp;running parallel to the course of the nerves and having the fissure whichnbsp;forms their aperture closed by a dense growth of hairs; on account of thisnbsp;peculiarity Renault has made a separate genus of this form, which henbsp;names Scaphidopteris Gilliotti, but this is hardly admissible. Lastly,nbsp;Renault has drawn attention to the water-stomata and epithemata over thenbsp;extremities of the nerves of the pinnae in a number of species; but thenbsp;genus Lageniopteris which he has founded on this character is quitenbsp;untenable, for these organs of excretion are observed in many Pecopteridaenbsp;and are probably widely diffused. They are most beautifully and clearlynbsp;shown in the figure which Renault has given of Lageniopteris obtusilobaquot;*.nbsp;The section has passed exactly through one of them in the longitudinalnbsp;direction, and we see the swollen club-shaped extremity of the tracheid-portion of the vascular bundle of the leaf surrounded by a small-cellednbsp;epithema, in which a wide canal of exit is closed by an unusually largenbsp;stoma. In the other form figured the organ is traversed by the section innbsp;an oblique and less favourable direction.

Rhachiopteridae, leaf-stalks of various orders of leaf-branching, are reckoned among the most numerous of petrified vegetable remains in whichnbsp;the structure is preserved, as might be expected indeed when we considernbsp;the stoutness and solidity of character which they usually possess, and thenbsp;wide distribution of Ferns in early periods of the earth�s history. Owing tonbsp;their uniformity of structure they are for the most part of small importancenbsp;to the botanist; still there are some forms among them which are in thenbsp;highest degree interesting, though unfortunately they have not yet beennbsp;fully explained. Their cross-section shows a homogeneous parenchymanbsp;inclosing a varying number of vascular bundles of very different and often

^ Williamson (1), VI. Renault''2), vol. iii, t. 19. nbsp;nbsp;nbsp;^ Renault (2), vol. iii, t. 19.nbsp;nbsp;nbsp;nbsp;^ Renault

Selenopteris there are two smaller bundles lying in its concavity. The Tempskyae are different; in one of them, Tempskya pulchra, Corda^, wenbsp;have several crescent-shaped bundles, one of which, the largest, often closesnbsp;into a ring. G�ppert ^ again has figured fragments of Gyropteris andnbsp;Zygopteris from the Carboniferous Limestone of Glatzisch-Falkenberg innbsp;Silesia, and with them, it is true, a form named Sphenopteris refracta, tonbsp;which we must return presently. Numerous figures of Zygopteris, Ana-choropteris, and other Rhachiopteridae from the English Coal-measures, innbsp;which the transverse section of the bundles differs from those alreadynbsp;described, are to be found in Williamson A number of petrifactions fromnbsp;the Upper Devonian beds (Cypridina-shales) of Saalfeld, but almost all innbsp;an extremely bad state of preservation, have been described by Unger ^nbsp;under many generic names. A large portion of these he has himself recognised as Rhachiopteridae; among them for example Clepsydropsis, whichnbsp;in the form of the transverse section of the vascular bundles agrees prettynbsp;closely with Williamson�s Rhachiopteris duplex�. For some of thenbsp;remainder he forms the groups Haplocalameae and Stereocalameae, whichnbsp;he would prefer to unite with Calamitae. After inspection of an originalnbsp;preparation of Calamosyrinx devonica, preserved in the Museum ofnbsp;Practical Geology in London, which belongs to the former of the twonbsp;groups, I should say that it is only the rhachis of a fern-leaf. What Ungernbsp;distinguishes in them as bundles of the pith may in fact be the vascularnbsp;bundles; the outer peripheral woody body will correspond, as I imagine,nbsp;to the mechanical subepidermal ribs of sclerenchyma. The figures ofnbsp;Kalymma Calamopteris and Calamosyrinx * should be compared.

A very remarkable fossil is the old Medullosa elegans. Cotta, which was afterwards named by G�ppert Stenzelia from specimens from thenbsp;Rothliegende of Chemnitz, and then Myeloxylon by Brongniart fromnbsp;material obtained at Autun. Both authors see more than one stock innbsp;this form, and G�ppert recognised it as one of his prototypes, whichnbsp;uniting in themselves the anatomical peculiarities of different main groupsnbsp;of the vegetable kingdom, in this case the Monocotyledons and the Ferns,nbsp;cannot be directly classed with any one of them. Williamson has examined specimens from the English calcareous nodules ; the plant has alsonbsp;been found in Bohemia with its structure preserved, for Corda�s�^ Palmacitesnbsp;leptoxylon and P. carbonigerus belong to it. Then on the strength ofnbsp;searching examination of many specimens from Autun and Grand� Croixnbsp;Renault declared that Myeloxylon is simply the stalk of a fern-leaf, and

' Corda (1), t. 58, ff. 1-5. nbsp;nbsp;nbsp;quot; G�ppert (12).nbsp;nbsp;nbsp;nbsp;� Williamson (1), vi, vii,nbsp;nbsp;nbsp;nbsp;* Unger (5-

5 Williamson (1), VI. t. 55. nbsp;nbsp;nbsp;� Unger (.5), t. i.nbsp;nbsp;nbsp;nbsp;� Unger (5), t. 2.nbsp;nbsp;nbsp;nbsp;* Unger (6), t.

� G�ppert (3). nbsp;nbsp;nbsp;Brongniart (2), p. 109.nbsp;nbsp;nbsp;nbsp;Williamson (1), vir.nbsp;nbsp;nbsp;nbsp;Corda (ll, tt. 19, 20-

accordingly altered Brongniart�s name into Myelopteris; he also endeavoured to prove ^ that these leaf-stalks belong to Alethopteris aquilina which is so common a species at Grand� Croix. Since that time no furthernbsp;doubt has been openly expressed with respect to the nature of these remains, though Schenk^ has lately contended that they are the leaf-stalksnbsp;of Cycads and not of Ferns. If I discuss them here with Ferns, it isnbsp;entirely from motives of convenience and after frequent examination ofnbsp;specimens in my possession; decisive proof of one or the other viewnbsp;appears to me to be still wanting.

The cylindrical leaf-stalks of Myeloxylon � (Fig. 14)�I use this name rather than Stenzelia because it is better known�are of unusually varying

thickness; I have some before me with a diameter of seven, eleven, and sixty millimetres, and Renault has figured some that are much thicker.nbsp;Their uniform parenchymatous fundamental tissue encloses a large numbernbsp;of vascular bundles, which though not quite regularly disposed yet formnbsp;numerous concentric circles. There are also many gum-passages, whichnbsp;are filled as a rule with some dark substance, and may be known by thenbsp;usually well-preserved epithelium. A rather broad subepidermal zone isnbsp;quite filled with one or more rows of crowded radiately disposed scleren-

� The latest observations have made it probable that the Myeloxyla are the leaf-stalks of the Medullosae described on p. 103. The owner of the precious bit of Medullosa Leuckarti mentionednbsp;there has recently had the lateral branch cut through transversely, and the section seems really tonbsp;show the structure of Myeloxylon, as far as can be determined without examination of thin slices.nbsp;If this unexpected find is confirmed by further investigation, a new and important weight will benbsp;added to the scale on the side of Cycadeae. 1 am indebted to Herr Leuckart�s kindness for mynbsp;knowledge of the specimen in its present state.

chymatous cell-groups, which sometimes enclose gum-passages, and the differences in the form of the transverse sections of these groups havenbsp;been employed for distinguishing species. These sclerenchymatous strandsnbsp;which are sometimes much crowded together never, as far as I know,nbsp;touch immediately on the epidermis, being everywhere separated fromnbsp;it by parenchyma; but it is true that the tissue-layers outside thenbsp;sclerenchyma-zone are very rarely preserved. The individual vascularnbsp;bundle shows a very characteristic structure, being undoubtedly collateralnbsp;with the xylem towards the centre. This part of the bundle, consisting of a variable number of broad scalariform tracheides, shows in allnbsp;cases, where there is any means of deciding this rather difficult question,nbsp;the narrow elements of the protoxylem on the side towards the phloemnbsp;of the bundle, as it is in Cycadeae; but the xylem next the phloemnbsp;which is present in Cycadeae (the bois centrifuge of French authors) isnbsp;entirely wanting. The phloem-portion is almost always destroyed, and innbsp;its place is a broad vacant space. But in bundles in which it is preserved, asnbsp;is the case in a specimen before me from Grand� Croix which belongs tonbsp;the collection at Strassburg (Fig. 14, B), it is entirely composed of delicatenbsp;thin-walled elements of which I can say nothing further, as I know themnbsp;only in the transverse section. The whole bundle is surrounded by a sheathnbsp;of small-celled parenchyma, the elements of w'hich, where they border onnbsp;the xylem, have their membranes thickened to a variable extent and arenbsp;changed into elongated sclerenchyma-cells. Now when Renault endeavoursnbsp;to prove that the remains which we are considering are of the nature ofnbsp;ferns, he relies chiefly on the following circumstances. First of all it isnbsp;certain that they were branched. This might have been concluded at oncenbsp;from the very great variations in the diameter, which if referred to onenbsp;rhachis would have led necessarily to the assumption that the leaf was onenbsp;of prodigious length. Renault ^ however has figured a superabundance ofnbsp;branched specimens. The leaf must therefore have been of considerablenbsp;size and repeatedly pinnate, and this is the case, as we know, in no recentnbsp;Cycad except Bowenia. Then it is in the highest degree remarkable thatnbsp;in the pebbles of Grand� Croix Myeloxylon is almost always associated withnbsp;detached and well-preserved pinnae of Alethopteris, that some fragmentsnbsp;contain nothing else,�a fact which is confirmed by the testimony of Renaultnbsp;and Grand� Fury 2, and which I can vouch for unreservedly from examination of specimens at my disposal. Lastly, Renault has observed thenbsp;structure characteristic of Myeloxylon in the very prominent median nervenbsp;on the under side of pinnae which belong by common consent and undoubtedly to Alethopteris, and has figured it� also, but unfortunately onnbsp;so small a scale that his drawings alone would not remove every doubt.

Schenk on the other hand takes his stand chiefly on the structure of the vascular bundles, which cannot, he thinks, be reconciled with that of Ferns ;nbsp;he does not go sufficiently into the argument drawn by Renault from thenbsp;branching. He is no doubt right in saying that the bundles have the habitnbsp;of those of Cycadeae, as appears more particularly in the position of thenbsp;protoxylem on the phloem-side of the xylem. But I am not convinced thatnbsp;there is any special resemblance between them and the bundles of Macro-zamia, as Schenk contends, for in the latter the xylem on the phloem-side isnbsp;well developed, while it is entirely wanting in Myeloxylon. Collateralnbsp;bundles also occur, as is well known, in Ophioglosseae and Osmundaceae,nbsp;nor are they uncommon in the Ferns generally, though it is true that theynbsp;are usually found only in the weak ramifications of the nerves of the laminaenbsp;of the leaves. It is therefore quite possible that in the forms from the Coal-measures this structure may have extended downwards as far as the axesnbsp;of the pinnae and the leaf-stalks ; and in our recent Marattiaceae, according tonbsp;Holle, the phloem is as a rule more strongly developed on one side in all foliarnbsp;bundles. The view here indicated, and which requires further investigation,nbsp;is at variance with one fact only, namely that, as Haberlandt has shown, innbsp;ferns with collateral bundles in which the protoxylem and protophloem arenbsp;in the normal position, the displacement of the former and its approximationnbsp;to the phloem, which are characteristic of the leaves of Cycadeae and occurnbsp;also in Myeloxylon, have never been observed. Williamson again, to provenbsp;that Myeloxylon is a fern, insists very particularly on the resemblancenbsp;between it and Angiopteris; but it appears from the foregoing remarks thatnbsp;this resemblance is confined rather to the general habit, though it must benbsp;acknowledged that the English fossils which go under that name do appearnbsp;from preparations, for which I am indebted to Williamsoids kindness, tonbsp;show deviations in structure and to approach nearer to that of Marattiaceae.nbsp;The figures too in Williamson give an essentially different position to thenbsp;fibre-strands. And now while I prefer not to give a decided opinion on thenbsp;systematic position of the leaf-stalk which we have been considering, becausenbsp;f see that further research is required fully to clear up the facts of the case,nbsp;f cannot help saying that the connection between the laminae of the leavesnbsp;of Alethopteris and the leaf-stalks of Myeloxylon cannot well be disputednbsp;Without crediting Renault with mistakes of observation, such as must not innbsp;^ny case be imputed a priori to so experienced an observer. It is anothernbsp;question whether the leaves thus reconstructed, which resemble fern-leavesnbsp;3nd by their structure remind us of the leaves of Cycadeae, should be placednbsp;the one or the other class. We cannot decide this question so long asnbsp;ffie fructification of Alethopteridae is unknown. Perhaps neither of thenbsp;alternatives is right; we may be dealing perhaps with an intermediatenbsp;group, and that there hav^e been such groups is becoming more and morenbsp;Pmbable. The reader should consult the remarks on this point on p, 141.

Before leaving the Rhachiopteridae and going on to fern-stems, it is necessary to mention one fossil, which, if it is really the leaf-stalk of a Fern,nbsp;would show what great anatomical differences, unheard of in our modernnbsp;vegetation, must have been exemplified in the ferns of the old deposits. Inbsp;speak of G�ppert�s ^ Sphenopteris refi'acta from the Carboniferous Limestonenbsp;of Glatzisch-Falkenberg in Silesia. I am indebted to the kindness of F.nbsp;Romer for a knowledge of several specimens from the Museum at Breslau,nbsp;which I hope to be able to examine more thoroughly at some future time.nbsp;Among them was the original specimen studied by G�ppert; the sections

which he had before him could not be found. The specimens arenbsp;irregulaidy-shaped fragments of verynbsp;hard calcareous grauwacke, whichnbsp;are traversed in every direction bynbsp;thin black lines, and show here andnbsp;there, but not often, minute bits ofnbsp;the pinnae of Sphenopteris. Thenbsp;one figured by G�ppert^, however,nbsp;is not to be found in the originalnbsp;stone, and was probably takennbsp;from another specimen. The fragments also contain longer portionsnbsp;of stalks which are often broken innbsp;the longitudinal direction, and havenbsp;their structure well preserved. Thenbsp;connection of all these pieces,nbsp;though it may be assumed to benbsp;probable from the peculiar penetration of the stone, has not however been certainly established ; for it does notnbsp;appear even from G�ppert�s remarks, which are unhappily too brief, whethernbsp;the rhachis through which his section passed was in dii'ect connection withnbsp;an evident fragment of a leaf-blade. For this reason I cannot at oncenbsp;dismiss Unger�s ^ opinion as untenable, though I do not myself share it.nbsp;He declares that the structure of this piece of leaf-stalk shows that itnbsp;cannot have belonged to a fern-leaf. Certainly its anatomy as illustratednbsp;by G�ppert�s beautiful figures is so peculiar, that I know nothing withnbsp;which it can be directly compared (see Fig. 15). Finst there is a moderatelynbsp;thick outer rind formed of tolerably uniform thick-walled parenchyma-cells arranged in radial rows. Beneath this is a much compressed andnbsp;inconspicuous tissue, a collection of larger and smaller woody masses ofnbsp;Irregular horseshoe-shape, which all turn their concavity outwards, and

towards the inside impinge so closely upon one another through the pressure of the intermediate tissue that their contour lines seem tonbsp;be modelled one upon the other. Goppert�s fine figure shows thatnbsp;the scalariform tracheides of these woody bodies are arranged in regularnbsp;rows, which radiate from the interior sinus to the convex outer boundary.nbsp;At the same time the diameter is very different in the different massesnbsp;of wood; some larger ones meet together in the centre, while othernbsp;smaller ones wedge themselves in between their shanks. The preparation which I was permitted to make from the original specimen alsonbsp;showed what does not appear in Goppert�s figures, namely that in thenbsp;sinus of each of these horseshoe-shaped cross sections and surrounded bynbsp;crushed tissue there lies a small vascular bundle of roundish outline, thenbsp;peripheral portion of which is everywhere of like structure and appears tonbsp;enclose within it the narrower elements, though these are not very clearlynbsp;seen (Fig. 15). Now where the structure is so anomalous, and especially innbsp;the absence of more searching investigation into a form which is knownnbsp;only in one or two fragments, it is very venturous to go at all beyond anbsp;mere description of the facts. Still in studying the section the thoughtnbsp;forces itself on my mind, that in the horseshoe-shaped woody bodies wenbsp;may recognise secondary growths, the product of cambium, and that thesenbsp;stand in some relation to the bundles in their sinus, either because thenbsp;bundle was collateral, or the zone of secondary tissue has been developednbsp;on the periphery of the phloem. However this may be, we can do nonbsp;more at present than record the existence of this remarkable fossil; let usnbsp;hope that we shall see our way in time to a fruitful comparison.

Fern-stems in great numbers have been described from very various formations. By far the larger part of them, being preserved in the form ofnbsp;casts only, possess extremely small interest for the botanist. When remainsnbsp;of this kind took the form of erect leafy stems with the leaves disposed innbsp;spirals, they were included byLindleyand Hutton^ and the earlier observersnbsp;under the collective name Caulopteris. This was certainly better than thenbsp;process of division commenced by Corda and pursued by various authors,nbsp;which being founded on unimportant characters could not possibly producenbsp;rational genera, and which was less necessary because the number of thenbsp;stems in question was by no means unmanageable. The scars left by thenbsp;detached leaves are in many cases more or less plainly marked on thenbsp;periphery of the casts. The stems are not unfrequently clad in an armournbsp;composed of spirally arranged leaf-stalks of different lengths, which crowdednbsp;together and interwoven with roots form a covering over the whole surface.nbsp;Casts of this kind, which do not even show the bundle-traces on the trans-'^crse section of the leaf-stalk with any distinctness, are recorded in the

literature under various generic names, Chelepteris, Cda, Bathypteris, Eichw., Sphallopteris, Sch., Anomorhoea, Eichw. Figures and explanationsnbsp;of these objects are to be found in abundance in Schimper�s Paleontologienbsp;V�g�tale. Another genus is Rhizomopteris, Schpr, embracing creeping fern-rhizomes, of which however there are not too many known. Nathorst 'nbsp;has figured some fine specimens from the Rhaetic beds of Schonen. Onenbsp;more genus may be mentioned, Schizodendron with a few stems of similarnbsp;appearance which have been described by Zeiller�. In other forms somenbsp;characters at least may be obtained from the mode of arrangement of thenbsp;bundle-traces on the leaf-scars, and genera may thus be distinguished,nbsp;though these too have but little real importance, as is .shown by the factnbsp;that the distribution of the bundles even in recent Ferns becomes so muchnbsp;changed in the base of the leaf and within small distances, that stems withnbsp;simple scars and stems clothed with leaf-bases cannot be compared together.nbsp;Moreover Zeiller^ has recently shown that two of the genera to be mentioned here, Stemmatopteris, Cda, and Caulopteris, Cda (not Lindl. andnbsp;Hutt.) may be omitted as being different surface-impressions of the samenbsp;stem. These two form-genera have on their surface large circular or elliptical scars, which in the former are sharply defined and smooth, in thenbsp;latter forked, and which almost touch one another in the orthostichies.nbsp;Each scar contains a closed circular or elliptical trace, and inside thisnbsp;another small trace in the form of a V or U opening upwards. Zeiller �nbsp;would see in the peripheral contour-line of the scar the boundary line of thenbsp;leaf-cushion, in the outer trace the boundary-line of the detached leaf-stalk,nbsp;and only in the inner V the bundle-trace. But it is also possible that, asnbsp;was supposed by the older authors the inner circular line may representnbsp;the trace of a circular vascular bundle, in which case the V would answernbsp;to the emerging strand of a medullary bundle-system. We cannot hope tonbsp;determine this point till we find a stem of the kind with its structure preserved, and this has not yet been done. .The name Protopteris is given bynbsp;Corda to all stems which have a single trace in their leaf-scars of the shapenbsp;here represented � . He has described several of these stems from the Coal-measures and one of the .same kind from the Permian formation under thenbsp;name of Thamnopteris Schlechtendalii **. Protopteris Witteana'� belongsnbsp;to the Wealden, the stem named Dicksonia Buvignieri to the Chalk.nbsp;Other individuals from the Chalk of Bohemia with a more complex andnbsp;many-stranded trace in the leaf-scars will be found figured in O. Feistmantelnbsp;as Alsophilina Kaunitziana, Dorm., and Oncopteris Nettwallii, Dorm.

1 Nathorst (2), t. i, and (4), t. i. ^ Eichwald (1), vol. i, 19, f. 9, and t. 20, f. ii. � Zeiller (9), t. 18.nbsp;nbsp;nbsp;nbsp;* Zeiller (9) and (10).nbsp;nbsp;nbsp;nbsp;* Zeiller (9).nbsp;nbsp;nbsp;nbsp;' Schimper (1).nbsp;nbsp;nbsp;nbsp;� Corda (!)�

' Eichwald (1), vol. i, t. 3, ff. 2, 3. nbsp;nbsp;nbsp;� Schenk (1), p. 226. t. 30, f. 6.nbsp;nbsp;nbsp;nbsp;Renault (2),

All the stems hitherto described are marked by the spiral arrangement of the leaves and the numerous orthostichies ; from these the genera Mega-phytum, Artis and Zippe, Corda, which are only known in the form ofnbsp;casts, are most sharply distinguished by the exactly distichous position ofnbsp;their leaf-scars. These genera have no direct analogies in recent vegetation,nbsp;for all recent fern-stems with distichous arrangement of the leaves arenbsp;prostrate and creeping, which was certainly not the case with the genera innbsp;question, for their structure is radial and exactly the same all round, andnbsp;there is no indication that one side was turned to the soil and bore roots.nbsp;The Megaphyta, of which many good figures are to be found in thenbsp;literature appear to have been confined entirely to the Coal-measures;nbsp;their huge shield-like leaf-scars are circular in form and in appearance likenbsp;those of Stemmatopteris. The large bundle-trace has usually the shape ofnbsp;a crescent opening upwards and with its horns bent inwards. There maynbsp;also be other smaller traces, the character of which has still to be investigated.nbsp;From the scale of the flattened cylindrical casts, a metre in length, whichnbsp;are met with occasionally, it would appear that these plants must have hadnbsp;tall erect and somewhat slender stems. A magnificent specimen is preserved in the collection of the Bergschule at Saarbriicken. The genusnbsp;Zippea^, founded on a few remains from the Bohemian Coal-measures, isnbsp;closely allied to Megaphytum, and the trace has the same character as innbsp;that genus, but the leaf-scars are much smaller and less prominent.

It has been already observed more than once that we are as a rule acquainted only with casts of the fern-stems of which we have hithertonbsp;been speaking. The inner structure can only be distinguished in a fewnbsp;cases, but in these it is found not to differ essentially from the ordinarynbsp;structure of recent stems. This will be seen by examining Renault�s �nbsp;figure of his Dicksonia Buvignieri, as also the transverse section of Caulop-teris Cottaeana of which however there is no figure showing the habit ;nbsp;the drawings also of Pecopteris Cottai � may be mentioned in this connection. It is uncertain whether this form comes from the Coal-measuresnbsp;or from the Rothliegende, since it has been found in the district ofnbsp;Schwemmland in the neighbourhood of Grossenhain in Saxony. Thenbsp;broad pith of this stem, of which I have seen a transverse section in thenbsp;Geological Department of the British Museum, is traversed by a ranknbsp;growth of thin extraneous rootlets which look at first sight like medullary bundles. A well-preserved stem of this kind from the Turoniannbsp;Chalk of Oppeln has been described by Stenzel � as Protopteris fibrosa.nbsp;From the same formation we have the specimen covered with a feltnbsp;of roots and named by Goppert Rhizopterodendron Oppoliense, which is

� Schimper (1), t. 52. nbsp;nbsp;nbsp;�� Corda (1), t. 26.nbsp;nbsp;nbsp;nbsp;� Renault (2), vol. iii, p. 73, t. g.

2 , vol. iii, t, 8, f. 10. nbsp;nbsp;nbsp;�� Corda (1), 1. 49.nbsp;nbsp;nbsp;nbsp;� Stenzel (3), t. 3, ff. 30-36-

also described as belonging to our present group and as coming from the same locality. In Zippea disticha ^ also it has been shown that the vascularnbsp;bundles formed a simple hollow cylinder. It is true that we have only thenbsp;cast of the stem, but the bundles are preserved inside it as quite thin stripsnbsp;of coal inclosed in the mass of stone ; this is a mode of preservation which asnbsp;far as I know is observed only in Saxony and Bohemia and near St. �tienne,nbsp;but which is of frequent occurrence in these districts, especially in the finenbsp;clays of Radnitz and the fine-grained sandstones of the Coal-measures ofnbsp;Chomle.

But there is another series of fern-stems from the Upper beds of the Coal-measures and from the Rothliegende, of which, in exact contrast tonbsp;those just discussed and by reason of their mode of preservation, we knownbsp;a good deal of the inner structure but very little of the character of thenbsp;surface. These stems, which bear the collective name of Psaroniae, arenbsp;distinguished by a system of circular vascular bundles one inside anothernbsp;like box within box, and show the structure characteristic of recent Marat-tiaceae, and of a few genera, such as Saccoloma, among Cyatheaceae andnbsp;Polypodiaceae. And now that we know how large a number of Ferns innbsp;the period of the Coal-measures had the fructification of Marattiaceae, wenbsp;have some justification for thinking that we see in the Psaroniae the stemsnbsp;belonging to these fructifications, though their mutual relations cannot benbsp;determined in all their details. The silicified Psaroniae of the Rothliegendenbsp;of Saxony and Bohemia have long been known, having been cut up wholesale during the last century to make ornaments for all kinds of objects onnbsp;account of the graceful designs which appear in the sections, so that verynbsp;few of them are now to be found. The surface is never preserved either innbsp;them or in the similar specimens from Val d�Ajol in the Vosges, from Kam-merberg near Ilmenau, from Autun or from St. Pltienne. I have also seennbsp;specimens in the same state of preservation in the British Museum from thenbsp;state of Ohio and from Brazil. They are usually shapeless fragments ofnbsp;small dimensions and weathered on the outside, but longer cylindrical stemsnbsp;of the kind are to be found in a few museums. Fragments of Psaroniae, in the same state as Zippea disticha, Corda just described, are alsonbsp;met with near Zwicka.u, Chomle and Radnitz, and are easy to recognise bynbsp;the peculiar arrangement of the vascular bundles which have been convertednbsp;into strips of coal. Lastly, Grand� Eury^ has found in the mines roundnbsp;St. �tienne whole stems in this state of preservation, still rooted in the soilnbsp;in which they grew, and has figured them under the name of Psaroniocaulon.nbsp;From these, as also from some of the silicified specimens, we learn that thenbsp;stems of these plants were long and cylindrical, and that the very gradualnbsp;conical enlargem.ent which appears in them towards the base is chiefly due

to the development of a covering of adventitious roots, which is of almost universal occurrence. It is this thick felt of roots more than anything elsenbsp;which conceals from our view the surface of the stemi and the form of thenbsp;trace in the leaf-scars. There are no silicified specimens without this covering, if we except Caulopteris Giffordi, Lesq.^ from the Coal-measures ofnbsp;Illinois which belongs here, and only a few instances can be adduced amongnbsp;the stems that are preserved as casts, and these perhaps represent the uppermost portions of the stem. Here too the leaf-scars are indifferently preserved as regards matters of detail, though it appears that the relativenbsp;positions of the leaves were not always the same ; in Psaronius Freislebeninbsp;for example, the leaves are in spirals with six orthostichies, while P. arena-ceus � shows only four orthostichies and P. carbonifer (P. musaeformis,nbsp;Corda has its leaves in two lines after the manner of Zippea and Mega-phytum. That there'are the like differences also in the stems which arenbsp;surrounded with a covering of roots may be concluded from the distributionnbsp;of the vascular bundles, which goes hand in hand wnth the position of thenbsp;leaves.

The anatomy of the stems of Psaroniae is very well known, thanks to Stenzel�s� careful and comprehensive researches founded chiefly on materialsnbsp;from Saxony and Bohemia. The P'rench specimens and those which arenbsp;not European have not yet been sufficiently studied. In the parenchyma,nbsp;which has in very many cases been destroyed, we find the characteristicnbsp;concentric net-work of vascular bundles, the several circles of which appearnbsp;to be united together here and there by radial connecting strands. Thenbsp;transverse sections of the vascular bundles form broad curved plates whichnbsp;in many cases have their margins bent inwards till they become hooked,nbsp;and are developed in larger or smaller numbers and are quite loosely ornbsp;extremely closely packed, according to the species. An instance of loosenbsp;arrangement of the bundles is seen in Psaronius Bibractensis in whichnbsp;moreover, in contrast to all other known species, solid sclerenchyma-bandsnbsp;of the same shape as the vascular plates are seen lying between them. Thenbsp;opposite condition appears in P. infarctus, Ung.^, in which the plates almostnbsp;touch one another. A firm lignified sheath enclosing the wffiole bundle-system of the stem is often present, but may be wanting both in this and innbsp;other species. The relative position of the vascular bundles on the transverse section of the stem is different in different species, and this is in directnbsp;Connection with the phyllotaxy, as we learn from the specimens describednbsp;above, which are preserved in the form of casts and show the outer surface.nbsp;In the specimens which have the leaves arranged in two lines (Fig. 16) they

* Lesquereux (1), p. 343, t. 60, ff. i, 2. nbsp;nbsp;nbsp;� Corda (1), t. 29.nbsp;nbsp;nbsp;nbsp;� Corda (I'll t. 28, ff. 5-9.

* Corda (1), t. 45, f. 3. nbsp;nbsp;nbsp;^ Stenzel (1); G�ppert (3).nbsp;nbsp;nbsp;nbsp;� Renault (2), t. 26, f. 2.nbsp;nbsp;nbsp;nbsp;�� G�ppert

form a transverse row in such a manner that all the margins of the bundles are towards the sides on which the leaves arise. Here we see the emergingnbsp;leaf-traces in the form of crescents surrounded by lateral sinuses in thenbsp;sclerenchyma-sheath, when this is present. In some cases the extremitiesnbsp;of the bundle-plates are united together by irregular bridges, the sectionnbsp;having passed exactly through a connecting strand. The arrangement isnbsp;much less regular in stems in which the phyllotaxy presents numerousnbsp;orthostichies; here the transverse section shows one or more bundlesnbsp;passing into the leaves, and from this Stenzel would conclude that the

leaves were arranged in spirals and whorls. But we may more readily refer these differences to the different elongation of the internodes in different species. In the case of very short internodes the traces of severalnbsp;leaves would naturally be together on the same transverse section. Therenbsp;is a fine apparently tetrastichous Psaronius to be seen in well-preservednbsp;silicified specimens in the British Museum, which would be suitable for thenbsp;determination of this question and which should be carefully examined.nbsp;It appears to have come from Brazil, and is said to have been brought bynbsp;Claussen from the Museum at Rio Janeiro. It is, as far as I know, thenbsp;only known specimen of a tetrastichous species in a condition to show the

structure. I may take this opportunity of saying that I am indebted to the kindness of Herr Schwacke of Rio Janeiro for some notices of stemsnbsp;of Psaroniae preserved in the museum in that city. The chief specimen,nbsp;forty centimetres in length, appears from the drawing before me not tonbsp;belong to the same species as the disks in the British Museum. Itsnbsp;history unfortunately is not certainly known, but various fragments ofnbsp;Psaroniae have been discovered in the provinces of Sao Paolo and Parona,nbsp;in company as usual with Araucaroxylon.

The centre of the stem thus constituted is surrounded by a rind of parenchymatous tissue of varying thickness, which is always so pierced andnbsp;traversed by countless crowded, unbranched adventitious roots runningnbsp;almost perpendicularly downwards, that its tissue appears as if it were onlynbsp;complemental tissue between the transverse sections of the roots. Each ofnbsp;these roots has a central stellate usually hexarc strand of xylem inclosednbsp;in a primary cortex of compact or loose parenchyma, which is surroundednbsp;on the outside by a strong dark-coloured cylinder of sclerenchyma; thenbsp;phloem-strands in the sinuses of the xylem are scarcely ever preserved. Thenbsp;sclerenchymatous tissue has no very sharply defined boundary-line, butnbsp;appears to be in immediate communication with the tissue of the stemnbsp;traversed by the roots ; this, according to the analogy of Ophioglossum andnbsp;of the roots which grow downwards in the base of the stem of tropicalnbsp;Lycopodiae, can only be due to very intimate secondary coherence of thenbsp;two parts. Stenzel ^ it is true takes a different view of the matter; henbsp;speaks of the roots, so far as they are inclosed in the cortical tissue of thenbsp;�Stem, as root-primordia; but this view is not easy to reconcile with whatnbsp;we know from more recent researches of the mode of formation of adventitious fern-roots. The sclerenchymatous envelopes of the roots are seennbsp;on the transverse section as delicate brown circles; the pitted appearancenbsp;which they produce on the surface of the section has given occasion to comparison with the breast of the starling, and in Germany to the trivial name ofnbsp;Staarstein. We should expect to find everywhere betw'een the transversenbsp;sections of the roots the transverse sections of the leaf-traces cut through atnbsp;different points in their course; but they are not to be seen, or only to anbsp;very limited extent and only in the vicinity of the axis of the stem. It isnbsp;conceivable that the trace on issuing from the leaf separates at once intonbsp;numerous bundles of minute size on the transverse section, and that thesenbsp;are lost to sight amid the mass of roots. On the other hand, we maynbsp;assume with Stenzel a considerable growth in thickness of the peripheralnbsp;parenchyma, the entire cortex, and that this takes place also at thenbsp;Surface where the leaves are detached from the stem and causes thenbsp;extremities of the bundles gradually to disappear within it.

sclerenchyma is less conspicuous in the small Gottingen stem ; every section through one of its leaf-stalks shows in the concavity of a crescent-shaped transverse section of a leaf-trace two other smaller roundish leaf-trace-sections.nbsp;The determination of these objects as stems of Osmundaceae rested at firstnbsp;on the habit only, which does certainly agree absolutely with that of Os-munda. But now that leaves have also been found in the same freshwaternbsp;quartz rocks in Hungary which have been declared to belong to Osmundanbsp;we must certainly allow that there are good grounds for this determination,nbsp;though it has not been proved that the stems have the characteristic coursenbsp;or the collateral structure of the bundles of Osmundaceae. The habit alonenbsp;would scarcely be sufficient, as is shown by a small and remarkable stemnbsp;from the Rothliegende of Chemnitz, which was first described by Cottanbsp;and has received from Corda �'* the name Asterochlaena Cottai, Corda. Anbsp;full description of this fossil is to be found in G�ppert*. I have myself-had opportunity of seeing a transverse section of it in the British Museumnbsp;which came from Cotta, and other specimens in the municipal collectionnbsp;at Chemnitz. On superficial examination it recalls Osmunditae, but it isnbsp;distinguished from that group by one very important particular; instead ofnbsp;a vascular bundle-ring in its axis, it has a single central bundle of considerable dimensions and with an irregularly stellate transverse section, thenbsp;rays of which are variously curved and sometimes also split into divergingnbsp;branches. This is a structure without a parallel in living Ferns, but something like it occurs apparently in another small stem from the Uppernbsp;Devonian beds (Portage group) of New York, which Dawson� has described and named A.steropteris noveboracensis, Daws. Here too there isnbsp;a star-shaped xylem bundle in the axis wdth long rays, which may benbsp;simple or regularly branched. A peripheral sclerenchymatous tissue incloses leaf-traces with a peculiar biscuit-shaped transverse section. Dawsonnbsp;has unhesitatingly placed this genus of his with Ferns, but from his ownnbsp;statements it is not impossible that it may belong to Lycopodiaceae; andnbsp;Unger�s� Cladoxylon, with which he compares it, is usually ranked withnbsp;that group. Cladoxylon itself will be considered in a later chapter withnbsp;Lycopodia.

Lastly, some very small herbaceous stems with simple structure are seen in the genera Zygopteris and Botryopteris, the fructifications and leafstalks of which have already been considered. That the stems in questionnbsp;do belong to these genera is well ascertained, for Renault'^ has found themnbsp;in actual connection with the characteristic leaf-stalks. In Zygopteris thenbsp;vascular body lies in the uniform parenchyma, which is traversed bynbsp;numerous leaf-traces, in the form of a closed ring surrounding a pith which

' Schimper (1), vol. i, p. 678. nbsp;nbsp;nbsp;Cotta (1).nbsp;nbsp;nbsp;nbsp;^ Corda (l),'p. 81.nbsp;nbsp;nbsp;nbsp;* G�ppert (3), p. 41 ;

9, f. I. nbsp;nbsp;nbsp;Dawson (4), t. 12.nbsp;nbsp;nbsp;nbsp;** Unger (5).nbsp;nbsp;nbsp;nbsp;^ Renault (2, 4, 5, 7).

The mass of roots which surrounds the axis may attain an enormous size and much exceed the diameter of the centre of the stem. In thenbsp;specimens from St. �tienne preserved as casts it appears as a layer ofnbsp;carbonaceous substance, which increases constantly in size as it approachesnbsp;the base of the stem; it can be recognised in this form in the sections ofnbsp;Psaronius carbonifer, Cda, figured by Corda Its size in the silicifiednbsp;specimens is in favour of the view that they are entirely the bases of stems.nbsp;Careful examination shows that this peripheral investment consists of twonbsp;distinct layers: first, the rind of the stem above described which is traversed by the roots; next, a mass of closely interwoven roots which projectnbsp;free above the surface, where they also show ramifications. These roots arenbsp;of course distinguished from the basal portions in the rind by the circumstance, that while sharply defined on the outside they still show a narrownbsp;parenchymatous rind lying outside the cylinder of sclerenchyma. Specimens showing the entire transverse section with the centre of the stem andnbsp;the whole of the enveloping mass of roots are rare. By far the larger partnbsp;of the Psaroniae preserved in collections are fragments of the envelopes,nbsp;sometimes of extraordinary dimensions. Similar silicified masses of entangled roots, belonging to other ferns and found in a fragmentary statenbsp;at Chemnitz, have been described as roots of Protopteris by Stenzel ^ whonbsp;compares them with Corda�s � figure of his Protopteris microrhiza. Theynbsp;are distinguished from those of Psaroniae by diarc root-strands. Suchnbsp;strands are found also in the compact root-investment of the stem knownnbsp;as Rhizopterodendron Oppoliense, G�pp. with the structure of Protopteris,nbsp;which comes from the Turonian beds of Oppeln, and for which Stenzel�s*^nbsp;elaborate description should be consulted.

Two small fern-stems, in which the thin herbaceous axis is surrounded by a closed woody panoply of leaf-stalk-bases lying close one on another, arenbsp;described in the literature under the name Osmundites. These are Osmun-dites Schemnicensis � from the Tertiary quartz rocks of Ilia in Hungary, andnbsp;O. Dowkeri�, also a Tertiary fossil from the Lower Eocene beds of Hernenbsp;Bay in England. A third quite similar silicified specimen, not yet described,nbsp;was picked up as a loose stone in the alluvium of the lower course of thenbsp;Lena in Siberia, and has found its way as part of Blumenbach�s bequest intonbsp;the palaeontological collection of the University of Gottingen. The centrenbsp;of all these stems is occupied by the ring of vascular bundles composed ofnbsp;very irregularly shaped transverse sections of bundles and surrounding thenbsp;parenchymatous medullary tissue. On the outer side of this ring is a thicknbsp;envelope of sclerenchyma, which is traversed by the crescent-shaped leaf-bundles, and to which the free leaf-stalks ultimately become attached. The

puts out rays in a stellate manner; in Botryopteris there is only a simple central strand with a roundish transverse section. The examination ofnbsp;Tubicaulis primarius ^ seems indeed to show that there were other andnbsp;much thicker stems with the structure of the leaf-stalk of Zygopteris, fornbsp;tolerably large fragments of that species have been found which have allnbsp;the characters of Tempskya (see above on p. i59)-

VIII.

EQUrSETACEAE, MARSILIOIDEAE, TRAQUAIRIA, SPOROCARPON.

There is nothing more indicative of the revolution, which has been accomplished in the domain of palaeophytology during the last twenty ornbsp;thirty years, than the fact that the Equisetaceae, which were formerly considered to be the best-known of all fossil vegetable remains, are now one ofnbsp;the groups with which we are not so well acquainted. The reason is that,nbsp;except in the case of Calamariae whose connection with Equisetaceae isnbsp;doubtful, we have no remain.s of this family before us in the form ofnbsp;petrifactions showing structure, but are limited entirely to casts and impressions. The smaller leafy branches and fructifications, the latter verynbsp;few in number, are known only in the form of impressions ; the main stems,nbsp;which are sometimes of great size, are usually found as casts; and thesenbsp;may be either casts of the broad cylinder of pith surrounded by a rind ofnbsp;coal, or may represent the outer surface of the stem itself Consequently itnbsp;is from the habit chiefly that the remains are determined ; we conclude thatnbsp;they are Equisetaceae from the sheaths with their toothed margins, fromnbsp;the big interior casts which point, as was said, to a broad cylinder of pith,nbsp;from the striated surface, and from the remains of fructifications which maynbsp;happen to be found with them. But most of these determinations in thenbsp;absence of any knowledge of the anatomy are to a certain extent insecure ;nbsp;and this insecurity is the greater, because we are acquainted with a series ofnbsp;forms having exactly the same habit, the Calamariae, in which the structurenbsp;is in many respects essentially different from that of our living Equisetae,nbsp;and because we do not know whether the forms supposed to be Equisetaceaenbsp;agreed in this respect more with the one or with the other group. Thenbsp;latter difficulty meets us of course chiefly when dealing with the remains ofnbsp;the Palaeozoic and Mesozoic deposits; doubts and considerations of the kindnbsp;are less important in the case of the many described Equisetitae from thenbsp;Tertiary formations which will be found collected together in Schimpernbsp;The period of the greatest development of Equisetaceae appears to have been

that of the Trias, the most gigantic forms of the group being peculiar to the upper members of that formation. Their importance in the general vegetation diminishes as we reach Jurassic times, while in the Coal-measures innbsp;the other direction only a few impressions have been found and these notnbsp;wholly above suspicion.

The best-known remains of Equiseteae belong to the genus Equisetites, which Schimper frankly terms Equisetum. One of the most typical speciesnbsp;and at the same time the most gigantic in size is Equisetites arenaceus,nbsp;Bronn, which is characteristic of the Keuper and especially of the Lettennbsp;Kohle, and is found in splendid specimens in the Stuttgart Schilfsandsteinnbsp;in the neighbourhood of VV�rzburg and Heidelberg. Many good figures ofnbsp;it are given in Schimper^. This species has been found in the above localities in very various states of preservation Large cylindrical pieces of erectnbsp;shoots which may be of the thickness of an arm are of very frequent occurrence, and show the leaf-sheaths and the surface of the internodes both in thenbsp;mould and on the cast. The surface is characterised, as in living species, bynbsp;alternating ridges and furrows, which are not very prominent on the wholenbsp;but become more distinctly marked towards the sheath. The alternation ofnbsp;these is often plainly to be seen on the successive internodes, but is sometimes obscure. The sheaths are tubular and are closely applied to the stem ;nbsp;they have their upper margin divided into short but very numerous teethnbsp;(Schimper states that he has counted more than one hundred in stout specimens), and each tooth ends in a long thorn-like process. The basal portions ofnbsp;the erect shoots, by which they are attached to the rhizome, are sometimesnbsp;disclosed to view. Pieces of stem of this kind narrow gradually and becomenbsp;conical, the internodes being shortened at the same time; they are thusnbsp;easily distinguished from the upper extremities of shoots, which are alsonbsp;sometimes preserved and are seen to narrow but slightly and to benbsp;rounded off into a dome-like termination. We sometimes get a view ofnbsp;such shoot-tops, especially in buds formed on the rhizome, either verticallynbsp;compressed or from above and then the shortened internodes with theirnbsp;sheaths are seen as so many concentric circles.

Nodal diaphragms of solid construction are found in Equisetites arenaceus, as in our living species; they are often preserved, and are thennbsp;usually attached to the sheaths which belong to them. They are notnbsp;unfrequently disclosed in splitting the stone, especially where the stems lienbsp;across the stratification; the sheath is in that case always vertically compressed and spread out flat. The diaphragm, when well preserved, shows anbsp;flat unsculptured central field and a raised and rounded ring, in which thenbsp;impressions of the vascular bundle-system can be distinguished as radiatingnbsp;furrows or folds. It is possible that Emmons�^ genus Lepacyclotes from the

Schimper (1), tt. 9-11. Schimper (1), t. 9, f. 3.nbsp;^ Kmmons (1), t. 3, ff. 4, 6.

Keuper of N. Carolina may be such a sheath-bearing diaphragm of an Equisetaceous plant.

Casts of the broad medullary cavity of the stem are also extraordinarily abundant, finely striated cylinders, which separate by sharp incisions intonbsp;portions answering to the internodes; the striation, following the course ofnbsp;the vascular bundles, is quite regular in its alternations. Each furrow innbsp;such a cast may have come from a vascular bundle, which projected as anbsp;slight rib on the wall bounding the medullary cavity. The incisions at thenbsp;nodes are the places where the homogeneity of the cast is interrupted bynbsp;the presence of the diaphragms. Objects in this state of preservation arenbsp;described in the older authors as Calamites arenaceus on account of theirnbsp;resemblance to stems of Calamitae which we shall consider presently; theirnbsp;connection with Equisetites was first demonstrated by Petzholdt^ andnbsp;Ettingshausen The latter states that he has seen Equisetitae in Bronn�snbsp;collection, which had a Calamites arenaceus inside it as an interior cast.nbsp;Portions also of the rhizomes of the plants occur frequently in a similarnbsp;state of preservation to that of the erect stems, and sometimes with thenbsp;lateral buds of the shoots attached They are distinguished, where thenbsp;surface can be seen, by the absence of the leaf-sheaths which were destroyednbsp;at an earlier period, and by the numerous scars of larger branches and stemsnbsp;present on the nodes. Together with all these remains there have beennbsp;found in the sandstones of the Keuper in many localities casts of the shapenbsp;of roundish usually somewhat flattened tubers often with folds on thenbsp;surface, which show an insertion-scar on one side and are of considerablenbsp;dimensions, though their size varies greatly^. Though these bodies havenbsp;never been found, as far as I know, actually attached to the rhizomes, yet anbsp;consideration of the facts in the case of Equisetites Burchardti, Dunk, isnbsp;sufficient to show that they are the well-known thickened portions ofnbsp;rhizomes of our Equiseta. The Museum at Gottingen contains plates withnbsp;long pieces of the rhizome of this much smaller species, which is foundnbsp;in the Wealden of Hanover, and to these are attached a number of thenbsp;roundish tubers which are similar in character to them. Schenk� gives anbsp;figure of one of these rhizomes. Lastly, the soft gray clays of the Letten-kohle of Basle have supplied, in company with numerous flattened stems ofnbsp;Equisetites arenaceus preserved in their rind of coal, groups of the mouldsnbsp;of polygonal scutiform bodies �, which are said to be the remains of thenbsp;fructifications of the stems. It is quite possible that this view is correct.nbsp;Each shield has a flat space in the centre (the apical surface), which isnbsp;bordered all round with narrow right-angled sloping planes answering tonbsp;the number of its sides.

In the formations which succeed the Keuper much smaller species take the place of Equisetites arenaceus ; E. Miinsteri, for example, which has beennbsp;fully discussed by Schenk is characteristic of the Rhaetic deposits. Thisnbsp;species is distinguished by its broad flat furrows and its sharp ribs, of whichnbsp;there are a few only in the circumference of the stem. A globular fructification has been found attached to the organs of vegetation. In E. colum-naris ^ from the Lower Oolite of Scarborough and Whitby we have anothernbsp;colossal form resembling E. arenaceus. Several smaller species from thenbsp;same formation in the Southern Alps have been examined by Zigno �; ofnbsp;E. Burchardti from the Walderkohle we have already spoken. It isnbsp;unnecessary to go further into the consideration of the many formsnbsp;described from the more recent formation.

Having thus proceeded upwards in our survey from the Equisetites arenaceus of the Keuper, we must add a few words respecting the pre-Tri-assic Equisetaceae. There are first the remains from the Coal-measuresnbsp;which Schimper * has brought together under the name Equisetides. Asnbsp;these are only short bits of stem with single sheaths and nothing is knownnbsp;of the fructifications, they must be classed among the most doubtful ofnbsp;fossils. Equisetides lingulatus � from the Coal-measures of Wettin and E.nbsp;brevidens� may be mentioned as the best-known examples. The morenbsp;thorough examination of these species must be preceded by the procuringnbsp;of material from the coal-districts, for there are but few specimens in thenbsp;collections. They do not appear to be at all abundant, but they arenbsp;inconspicuous and may have been overlooked. The reader should refernbsp;to the remarks which will be found on a later page in connection withnbsp;Cingularia and Calamostachys. Dawson'' has figured as Equisetidesnbsp;Wrightiana a very unlikely looking fossil from the Upper Devonian beds ofnbsp;Chemung; this according to Hall � is the remains of a Crustacean, andnbsp;represents two abdominal segments of a creature not unlike the genusnbsp;Stylonurus.

Here must be mentioned the fossil known as Equisetum mirabile�, a peculiar form, in which there is much that still remains to be determined;nbsp;a full discussion of it accompanied by fine and careful figures will be foundnbsp;in Weissand Stur 'k The latter author has founded a new genus for thisnbsp;plant, and named it Eleutherophyllum. Equisetum mirabile is one of thenbsp;very rarest of the fossils of the Coal-measures, and has hitherto been knownnbsp;only in a few fragments of impressions from the Waldenburg district. Sturnbsp;has given the names of the Museums in which these specimens are preserved.

^ Brongniart (1), vol. i, t. 13. nbsp;nbsp;nbsp;� de Zigno (1), vol. i. * Schimper (1),

5 German (1), t. 10, f. 3 ; Weiss (5), t. 16, f. 10. nbsp;nbsp;nbsp;� Schimper (1), t. 17, f. 4.

* Wright (1), Explanation to t. 15, f. i. � Sternberg, Graf von (1), Heft 5-8, Weiss (6), p. 133; t. 18, f. 2, and (5), p. 149; t. 16 a, f. 9.nbsp;nbsp;nbsp;nbsp;� Stur (5),

The thick cylindrical flattened sterns are divided by many nodes into very short members with longitudinal waved ribs, which alternate regularly fromnbsp;node to node. The nodes bear impressions of organs which are supposednbsp;to be leaf-teeth with flatly rounded extremities. These leaf-teeth accordingnbsp;to Stur are free, according to Weiss they are united below into a sheath.nbsp;A peculiar sculpture observed on the surface indicates according to Stur thenbsp;presence in each tooth of a sporangium, which glimmers faintly through thenbsp;surface of the leaf; the whole would therefore belong to the fructifications.nbsp;But Weiss has been unable to convince himself of this; he believes that thenbsp;appearance is due to small folds caused by the firm pressure of the sheathnbsp;Upon the zigzag line connecting the ribs, which unite together in the nodes.nbsp;Further examination of fresh material must decide these questions. Inbsp;have no opinion of my own, having had opportunity for a hasty look onlynbsp;at the plant.

The genus Schizoneura has found its place next to Equisetites since Schimpers ^ description laid the foundation of our knowledge of the group.nbsp;The oldest known species is from the Buntsandstein of the Vosges. Anbsp;second very closely allied form, S. Gon dwanensis from the Lower Gond-'vanas (Trias) of India has since been described and illustrated by numerousnbsp;figures; I have seen one specimen of it in the Botanical Department of thenbsp;British Museum. Two other species are less exactly known, S. Meriani �nbsp;Bom the Lettenkohle and S. Heerensis, Schpr.'* The stems of Schizoneura are divided into members and striated; O. Feistmantel distinctlynbsp;states that the ridges do not alternate. The long lax cylindrical sheathsnbsp;'vhich loosely embrace the stem have very short teeth to the upper margin,nbsp;nnd being torn in process of time between the fine nerves down to the basenbsp;they become separated into two or more spreading lobes of unequal breadth,nbsp;which look like whorls of leaves of some monocotyledonous plant, and havenbsp;given rise to the name Convallarites as employed by the older authors.nbsp;Numerous leafless stems and casts with the character of Equisetaceae, andnbsp;Bund with the leafy branches in the Lower Gondwanas, have been unitednbsp;fiy O. Feistmantel with Schizoneura.

Of the genus Phyllotheca, Brongn. we have in Europe only a few �'^mains in the Oolitic strata of the Southern Alps, and these have beennbsp;described by Zigno� as Ph. Brongniartiana and Ph, equisetifornjis. Severalnbsp;�ther species, among them Ph. australis originallydescribed by Brongniartnbsp;peculiar to the Trias of Australia� and the Lower Gondwanas of India.

Schimper (3), tt. 24-26, and (1), vol. i, p. 282; tt. 13, 14 ; Zittel (1), p. 161. nbsp;nbsp;nbsp;� Pal. Ind.

pt. ir. nbsp;nbsp;nbsp;= Schimper (1).nbsp;nbsp;nbsp;nbsp;� Nathorst (3), t. i; Heer (14), tt. 1, 2.

quot;e Zigno (1), tt. 7, 8. nbsp;nbsp;nbsp;� Brongniart (4), p. i;;!.nbsp;nbsp;nbsp;nbsp;' M'Coy (1); O. Feist-

We may pass over certain remains in an extremely bad state of preservation, which have been thus explained by Schmalhausen ^ without apparent reason and have been figured by him ; but this author has also describednbsp;and figured^ some highly remarkable objects as fructifications of his Phyllo-theca deliquescens. I had opportunity of seeing the second of his twonbsp;specimens in Strassburg, where it had been sent by him from St. Petersburg to be prepared. It is admirably rendered in the drawing in Fig. 17,

A striated axis with sheaths thoroughly like those of Phyllotheca bears on the internodes between the sheaths in a lateral position certainnbsp;small organs, which are exactly likenbsp;the sporangiferous peltate disks of ournbsp;Equiseta. They lie indeed in numbersnbsp;all round the axis in the interval betweennbsp;every two sheaths. The other specimennbsp;has just the same appearance, but onlynbsp;egt;ne sterile sheath is preserved in itnbsp;together with portions of the two adjoining internodes.

Since these specimens have both of them the characteristic foliar sheathsnbsp;of Phyllotheca, it seems unreasonable tonbsp;doubt whether they belong to thatnbsp;genus, which would thus differ from truenbsp;Equisetaceae in having its fertile spikesnbsp;I'epeatedly interrupted by ordinary vegetative leaf-whorls. But in any casenbsp;Heer � is not justified in uniting withnbsp;his Phyllotheca sibirica two spikes ofnbsp;another species, which he thinks himselfnbsp;are very like those of Ginkgo, merelynbsp;because they He beside it in the speci-nien, and then going on to speak ofnbsp;different types � which in time will have to be made into separate genera.�

All that we know of fossil Hydropteridae is so small, so fragmentary, and for the most part so doubtful, that we may proceed at once to givenbsp;some account of them. From the group of Marsileaceae Heer� describesnbsp;fhe fruit-capsules of a Pilularia from Oeningen; Marion � has found in thenbsp;Hpper Eocene beds of Ronzon (Haute Loire) an opened capsule, which hasnbsp;since been recognised by A. Braun ^ as the fruit of a Marsilea (M. Marioni,

Schmalhausen (1), t. 9^ f. 17. nbsp;nbsp;nbsp;^ Schmalhausen (1), t. i, f. 3, and t. 9, f. 16.

^ h p. 9 ; t. I, f. 5. nbsp;nbsp;nbsp;^ Schmalhausen (1).nbsp;nbsp;nbsp;nbsp;^ Heer (3), vol. i�, t. 145.

Heer ^ and Schmalhausen -; in the latter author will be found an incidentally inserted monograph of the genus. Lastly, Equisetum laterale, Phill. from the Lower Oolite of Scarborough � has been removed by Heer to thenbsp;genus Phyllotheca, to which it must belong rather than to Schizoneuranbsp;where it is placed by Schimper

It is chiefly by their habit that the leafy shoots of Phyllotheca are distinguished from those of Equisetitae. The striation according to Schmal-hausen does not alternate in the successive internodes. The leaf-sheathsnbsp;are closely appressed, becoming wider and funnel-shaped above in somenbsp;species ; their margin bears an unusually large number of linear muchnbsp;elongated obtuse one-nerved teeth, which diverge and curve outwards, andnbsp;are sometimes again incurved at the points and become hooked. Thesenbsp;long-spreading sheath-teeth give a very peculiar habit to the genus (Fig.nbsp;17, A). In Phyllotheca indica and in the Siberian form Ph. deliquescens,nbsp;Schmalh. the branches are said to be arranged in whorls at the nodes, innbsp;other species to stand singly and with their points of insertion in some casesnbsp;beneath the node-line, in others above it. This is all that I can say withnbsp;respect to the characters of the branching, as I have no knowledge of thenbsp;original specimens. Casts accompany some of the species, according tonbsp;M'^Coy and Schmalhausen, and show the well-known striation, but havenbsp;the nodal lines less deeply incised. If there are any branch-scars, they arenbsp;placed exactly on the node.

Circular disks of peculiar appearance are often found with the branches of Phyllotheca, and are usually explained to be the nodal diaphragms ofnbsp;that genus. They lie most frequently on the internodes of the leafy stemsnbsp;on one side of them. They occur with Equisetum laterale, Phill. fromnbsp;Scarborough in the same manner as with the Asiatic forms, and have givennbsp;it its name, and it is for this reason that Heer has removed the plant tonbsp;Phyllotheca. The disks show very pretty sculpturing. They are planenbsp;and smooth in the middle, but their curved margin is marked with anbsp;strong radial striation. I have seen many specimens in the Museum atnbsp;Oxford with a thick covering of coal, which was split at the periphery intonbsp;numerous lobes corresponding to the striation, and on the lobes appearednbsp;small and peculiar scars. In presence of these facts the usual explanationnbsp;of these structures appears to me, as to Heer, very doubtful. If it is correct,nbsp;it is not easy to see why they are so often found in a lateral position at thenbsp;middle of the internodes ; we are driven to the very arbitrary assumption,nbsp;that they represent the lowest nodes of the lateral branches which werenbsp;inserted above the line of the nodes of the stem.

to be macrospores of Lepidodendreae, Radiolariae, and zygotes of Desnii-dieae. It appears to me, and to Strasburger ^ also, that if they can be compared with anything, it is first of all with the massulae of Azolla, ornbsp;with the sporocarps which contain them ; and though this comparisonnbsp;must be distinctly proposed as a possibility only, we may neverthelessnbsp;consider these remains in this place, since none more appropriate has beennbsp;found.

Sporocarpon compactum ^ is a small spheroidal body scarcely visible to the unaided eye, and consists of a stout solid case of very peculiarnbsp;structure inclosing an inner cavity, which contains a variable number ofnbsp;round smooth-walled cells. Outside andnbsp;between these cells is a brown and formlessnbsp;mass, but they are also not unfrequentlynbsp;clothed with a thin folded membrane. Thenbsp;case is itself composed of a homogeneousnbsp;structureless firm inner leaf with a doublenbsp;contour-line, and on this leaf and occupying the position of a compact palisade-tissuenbsp;are hollow cylindrical bodies, which grownbsp;narrower and cone-shaped towards the apex,nbsp;or in some cases are prolonged into conicalnbsp;hairs, and form a closed rind; no contentsnbsp;are discoverable in these bodies, and theirnbsp;wall is formed of the same substance asnbsp;the leaf on which they rest, but is ofnbsp;slighter consistence. Williamson has employed the sculpturing of the outer casenbsp;to distinguish several other species ofnbsp;the genus; in his Sporocarpon elegans (Fig. 18, i?) the hollow cylinders which form the rind have the shape of an hour-glass and leavenbsp;empty spaces or cell-like gaps between them, but are in immediatenbsp;contact at base and apex all the way round. Some of them also arenbsp;prolonged into long conical hairs, Williamson^ supposes that this wasnbsp;originally the case with all of them, but that in the greater number thenbsp;hairs have been broken off. Another form resembling Sporocarpon compactum without hairs is named by Williamson � S. tubulatum. In a few othernbsp;forms also placed in the group, S. pachyderma �, S. asteroides and S.nbsp;ornatum the layer of cylindrical bodies is replaced by a thick frothy mass

A. Br.). The leaves of the plant are still unknown in the fossil state. Some remains also from the older formations have been placed by authorsnbsp;with Hydropteridae, the genus Sagenopteris, Presl, for example, the leavesnbsp;of which were noticed above on page 138. Zigno ^ has observed some smallnbsp;round bodies in company with these leaves, and Nathorst who foundnbsp;similar objects in Schonen, thinks that they are sporocarps, but has givennbsp;no reason for his opinion. He then proceeds to argue in a manner whichnbsp;is little convincing that these sporocarps belonged to Sagenopteris, andnbsp;that Sagenopteris therefore was one of the Marsileaceae. Schimper � toonbsp;has since given his assent to this view.

It is extremely doubtful whether the fossil leaf described by Schenk as Marsilidium speciosum from the Wealden formation of Osterwald innbsp;Hanover, which was placed in the group which we are considering solely onnbsp;account of the habit of the single original specimen, really belongs to it.nbsp;The lamina is formed of six broadly wedge-shaped pinnae inserted on thenbsp;end of a long petiole ; the nervation is that of Cyclopteris and the anteriornbsp;margin is finely toothed.

Remains of leaves have been described from the Keuper of N. Carolina as Sphenoglossum quadrifolium � ; they consist of four broadly wedge-shaped entire leaves or pinnae, which lie in one plane and are inserted at the same point.

The family of Salviniaceae, represented by several well-preserved and indubitable species of Salvinia, has been found in the form of impressionsnbsp;of leaves In the Miocene strata of Schrotzburg in Switzerland and in thenbsp;same formation at Schossnitz in Silesia and at Priesen near Bilin in Bohemia�. No similar forms have been found in older deposits, nor have anynbsp;remains of Azolla, as far as I know, been described hitherto. This ofnbsp;course does not prove that these very peculiar plants had not made theirnbsp;appearance in the earlier periods of the world�s history. Their tendernbsp;vegetative organs perished perhaps by an early decay, and have not comenbsp;down to us. We may incline to this supposition in presence of certainnbsp;diminutive remains of fructification which are occasionally found in thenbsp;calcareous nodules of the English Coal-measures, and which have beennbsp;described in great numbers by Williamson � and by Carruthers undernbsp;the names Sporocarpon, Will., Traquairia, Carr., and Zygosporites, Will.nbsp;I have made acquaintance with a large number of specimens of thesenbsp;objects in Williamson�s collection, and I have some myself for which I amnbsp;indebted to his kindness and to that of Mr. W. Cash of Halifax. Theirnbsp;origin has been the subject of various conjectures ; they have been thought

' de Zigno (1), vol. i, t. 20, ff. 2, 3. nbsp;nbsp;nbsp;^ Nathorst (6). Zittel (1), p. 154.nbsp;nbsp;nbsp;nbsp;* Schenk (1),

t. 26, f. 3. nbsp;nbsp;nbsp;� Emmons (1), t. i, f. 2.nbsp;nbsp;nbsp;nbsp;� Heer (3), vol. iii, t. 145.nbsp;nbsp;nbsp;nbsp;�� Goppert (18), t. i.

ff. 21-23. nbsp;nbsp;nbsp;* ''on Ettingshausen (4).nbsp;nbsp;nbsp;nbsp;quot; Williamson (1), ix, x.nbsp;nbsp;nbsp;nbsp;Williamson (1), x.

consisting of many isodiametric cells lying one above another, and in S. ornatum the cells which are near the surface are also prolonged into irregular hairs. Closely allied to Sporocarpon is Traquairia, Carr. (Fig. x8, A),nbsp;which is distinguished from it by the structure of the outer layer of thenbsp;envelope, but agrees with it in all other points. Williamson�s tenthnbsp;paper in the Philosophical Transactions gives a full account of this genusnbsp;and some beautiful figures. The inner or supporting leaf of the envelopenbsp;has on it long spines forming hollow cylinders with obtuse extremities.nbsp;These give rise at regular distances to lateral branches of like character tonbsp;themselves, and these may in certain circumstances branch very copiouslynbsp;and anastomose, and thus present an extraordinarily complicated net-worknbsp;or sponge-like aggregate of hollow tubes, which is traversed in the direction of the radii by the much broader main canals formed by the spines.nbsp;These relations are shown with especial beauty in radial and tangentialnbsp;sections of the case, such as are figured by Williamson Zygosporites,nbsp;Will., a genus which owes its name to its likeness in habit to the zygotes ofnbsp;Cosmarium, may perhaps, judging from some figures of Williamson benbsp;found to belong to our present group. But this form, like Oidospora � andnbsp;Calcisphaera, Sollas^ found in the Carboniferous limestone in the neighbourhood of Chester, distinctly requires further investigation.

If now from this detailed statement of facts we turn to the different explanations which these objects have received, we must observe first thatnbsp;Carruthers� idea that they are Radiolariae, in support of which he appealsnbsp;to Traquairia, can scarcely be maintained. According to this view thenbsp;outer system of tubes must be homologous with the skeleton and the supporting lamella with the rind of the central capsule; the sarcode-bodynbsp;perished of course before petrifaction, but some remains of it were preserved in the inner cells. Haeckel, to whom Williamson� had sent his mostnbsp;important original preparations, assures us that there is no Radiolarian withnbsp;such structural conditions as we find in the remains in question. Williamson on the other hand sees in all these forms macrospores of Lepidodendreae,nbsp;and of allied forms which cannot be more precisely determined. He saysnbsp;in the supplement to his paper�, that he has received through Mr. Binnsnbsp;a series of sections of a � crushed Lepidostrobus, in all of which Traquairiaenbsp;occur under such conditions as leave no doubt that they are the macrosporesnbsp;of a Lycopodiaceous plant.� I have seen these preparations in his collection,nbsp;and I must acknowledge that small groups of Traquairiae or single Traquairiae do lie inside many of the sporangia. But the whole specimen isnbsp;so macerated that these might well have found their way in from the out-

� Williamson (1), X, t. 18, ff. 86, 87. nbsp;nbsp;nbsp;* Williamson (1), X, t. 19, f. 55.

IX, t. 25, f. 102. nbsp;nbsp;nbsp;�* Williamson (1), x, t. 20.nbsp;nbsp;nbsp;nbsp;= Williamson (1), x, p. 511.

side while it was rotting in the water, especially as other sporangia of the same cone contain small remains of tissue, which could not have got therenbsp;in any other way. And if the Traquairiae and Sporocarpae are macrospores,nbsp;how shall we explain the cells inside them ? Evidently there is nothing leftnbsp;but to consider them to be remains of the prothallium', the preservation ofnbsp;which, considering its delicate nature, would not be too probable. Nownbsp;these interior cells will give us less trouble, if with Strassburg and myselfnbsp;we compare the entire bodies with the massulae of Azolla. In this casenbsp;they may be either spores, or else remains of single vacuole-spaces of thenbsp;spongy net-work of massulae which surrounds the spores. The one andnbsp;the other may perhaps be there together. I have for instance seen in somenbsp;preparations in the collection of Mr. W. Cash two different kinds of interiornbsp;cells, both sharply defined, but in the one case with a single circumscribingnbsp;line, in the other with an evident doubly-contoured membrane. Williamsonnbsp;objects to our view, that there are indubitable macrospores with interiornbsp;cells, which are recognisable by their shape and by their strongly thickenednbsp;membrane beset with appendages on the outside. It is certain that therenbsp;are receptacles of the kind which come very near in form to undoubtednbsp;macrospores, as will be seen by comparing the figures which Williamson ^nbsp;has given of both these objects. But that the outer surface of the massulaenbsp;could vary much in character is shown by the differences which we find innbsp;this respect in the few living representatives of the genus Azolla ; and thenbsp;perinium of the macrospores which has a similar origin may easily havenbsp;developed a similar configuration to that of the other sexual form. Innbsp;conclusion, I may say that nothing has confirmed me in this view of minenbsp;so much as a preparation quite recently made by Mr. Binns and not yetnbsp;described, which I had the opportunity of seeing when I was with Mr. Cash.nbsp;A dark very thick-walled capsule resembling a macrospore encloses a number of cell-like spherical bodies closely crowded together, each of which isnbsp;filled quite full with small well-preserved microspores. In the same preparation is another similar capsule containing only a single mass with anbsp;frothy vacuolated appearance. The obvious view is that the capsule isnbsp;a sporocarp, in which the solid tissue is no longer visible, and that thenbsp;globular bodies are massulae which conceal spores. The other specimennbsp;Would in that case answer to an imperfectly developed conceptaculum, thenbsp;contents of which had stiffened into a sporeless ball of froth. However, Inbsp;have no doubt that by continued research we shall in time arrive at a morenbsp;perfect understanding of these objects.

We find mention in the literature of a considerable number of remains which exist in the form of impressions and are known by the name of Lyco-podites and Selaginites. These are either heterophyllous forms and resemblenbsp;Selaginella, or they are homophyllous branches beset all round with crowdednbsp;scale-like leaves, and putting us in mind rather of true Lycopods. It is ofnbsp;course impossible, without accurate knowledge of the fructifications whichnbsp;are either wanting or are indistinctly shown, to keep these two groups separate from one another. As regards the homophyllous forms, their externalnbsp;characters are not very pronounced, and this necessarily introduces uncertainty of various kinds into the determination. Many remains once termednbsp;Lycopoditae have since proved to be branches of Conifers, for examplenbsp;Lycopodites Stiehlerianus, G�pp. which is now Walchia, or branches ofnbsp;certain Lepidodendrae which will be discussed presently. On the othernbsp;hand, Lycopoditae may easily be mistaken for some of the larger Mosses,nbsp;the impressions of which cannot be distinguished with perfect certainty fromnbsp;those of delicate Lycopodiae. As instances of this kind maybe mentionednbsp;Lycopodites Maakii^ from the Coal-meiisures of North America, and L.nbsp;uncinatus also from the Carboniferous; the latter form by its branchingnbsp;and the hooked curvature of its extremities reminds us in the most strikingnbsp;manner of certain Hypneae. Even fern-stems covered with paleae maynbsp;be confounded with Lycopoditae, as is done by Schimper in the case ofnbsp;Selaginites cavifolius�, which its author compares with Selaginites Erd-manni^ usually reckoned among Ferns. Still there can scarcely be anynbsp;doubt but that certain homophyllous branches described by Goldenbergnbsp;from the Coal-measures of Saarbr�cken (Lycopodites elongatus �, L. denti-culatus�) are really of the nature of Lycopods. A remarkably fine formnbsp;with the habit of Lycopodium Phlegmaria and with thick clavate terminal

� Lesquereux (1), t. 62, f. i. nbsp;nbsp;nbsp;^ Lesquereux (3), vol. ii, t. 41, f. 3.

vol. �, t. 39, f. 8. nbsp;nbsp;nbsp;* Germar (1), t. 26.nbsp;nbsp;nbsp;nbsp;� Goldenberg (1), t. i, f. 2.

fertile spikes has been described by Kidston^ as Lycopodites Stockii. It comes from the Millstone Grit of Scotland. The figure does not enablenbsp;us to feel sufficiently sure about the Devonian Lycopodites Matthewi ^ fromnbsp;New Brunswick. I know of no homophyllous Lycopoditae from othernbsp;younger formations.

It is only in the case of a few of the heterophyllous Selaginella-like forms that the presence of the small ventral leaves can be ascertained ; ifnbsp;the impression is seen from above, they are of course concealed, but in thenbsp;opposite position also they are usually withdrawn from observation throughnbsp;their clinging close to the stem. For this reason all Lycopoditae withnbsp;distichous leaves may be reckoned without hesitation among heterophyllousnbsp;forms. A good description of two forms from the Coal-measures, Lycopodites primaevus, Goldenberg and L. macrophyllus, Goldenberg will benbsp;found in Goldenberg. The former species is provided with terminal fructifications like closed buds, and a very similar form, L. Gutbieri, Gopp., alsonbsp;bears fertile catkins ; a figure of it is given in Schimper L. Richardsoni,nbsp;Daws, from the Upper Devonian beds of America has been placed bynbsp;Dawson� in this group, but is extremely doubtful. The figure shows anbsp;small branch like a Graptolite beset with distichous tooth-like leaves (?), andnbsp;attached to it a short lateral branch also with distichous leaves but ofnbsp;different shape and limited growth, of which it is briefly said in the description, � fertile branches, lateral, one-sided, in the form of sessile strobiles.� Itsnbsp;author, as usual, gives no particular reason for this assertion. From morenbsp;recent formations the only plant which I know belonging to this group isnbsp;Lycopodites falcatus� from the Oolitic deposits on the coast of Scarborough, which is distinguished by the loose disposition of its leaves andnbsp;by the hook-like forward curvature of the extremities of its elliptical entirenbsp;leaves.

Renault ¹ on the other hand has found in the siliceous fragments of the Upper Coal-measures of Autun small broken pieces of diminutive stems ofnbsp;two different kinds, which from their structure do most probably belong tonbsp;this group, though their surface-view unfortunately is not known. He hasnbsp;named these forms Lycopodium punctat�m and L. Renaultii. The transverse section in both forms shows an axile bundle-strand containing scatterednbsp;groups of vessels and reminding us to some extent of that of Lycopodiumnbsp;Phlegmaria. Numerous weak horizontal strands are given off from it at thenbsp;same height, and pass through the cortex into the �leaves. From thenbsp;regularity with which these are seen all round the transverse sectionnbsp;Renault concludes that the leaves which are not preserved were arranged in

whorls. The longitudinal section teaches us that the leaf-circles must have been separated from one another by only shoi't internodes. It is peculiar,nbsp;that reticulately thickened tracheides are found in Lycopodium Renaultii,nbsp;and tracheides with several rows of bordered pits polygonally flattenednbsp;by mutual pressure in L. punctatum, while in recent species scalariformnbsp;tracheides are the prevailing form ; but Renault states that he has observednbsp;pitting of a similar kind in several living species. As I have been unable tonbsp;procure the only species, L. pachystachyum, cited in proof of this statement, I have been unable to verify it. We feel here very disagreeably ournbsp;want of knowledge of the inner structure of Lycopodiaceae. Fibre-strandsnbsp;are developed in the cortex of L. Renaultii, and are wanting in the othernbsp;species; in these the transverse sections of roots with normal pentarchnbsp;bundles are seen in the middle of the cortical parenchyma. This featurenbsp;reminds us strongly of living Lycopodiae, in which it was discovered bynbsp;Brongniart ^ at the base of the stem and illustrated by excellent figures.

� It may be probable that Unger�s^ Arctopodium from the Cypridinae-**slates of Saalfeld belongs to our present group, as its author supposes. Unfortunately the ill-preserved remains are known only in transversenbsp;sections, which show in the centre of the stem a group of vascular bandsnbsp;vividly recalling our Lycopodiae. These bands are radially disposed innbsp;Arctopodium radiatum variously twisted, curved and branched in A.nbsp;insigneThe cortex is destroyed in both cases and nothing can be seennbsp;of the leaf-bundles. On the other hand, the specimen described by Ungernbsp;at the same place under the name of Cladoxylon mirabile� is quite doubtful.nbsp;Here the vascular plates, if such they are, unite in the middle into annbsp;irregular mesh-work; but I have satisfied myself by examination of annbsp;original preparation in the Jermyn Street Museum in London of the hopelessly bad state of preservation of this fossil. Only the discovery of freshnbsp;specimens will give us the needful certainty respecting it. Such specimensnbsp;are said by Dawson� to be already in our possession from the Uppernbsp;Devonian beds of N. America (Styliola limestone), but we have at presentnbsp;only superficial descriptions of them. Unger would unite another form ofnbsp;this genus of his, Cladoxylon dubium^, with Sphenopteris refracta whichnbsp;was noticed above on p. 164, and it cannot be denied that there is a certainnbsp;resemblance between them. The genus Asteropteris, Daws, has beennbsp;already discussed on p. 173 in connection with Asterochlaena. Its centralnbsp;star-shaped vascular bundle, but especially the regular simple ring ofnbsp;emerging leaf-bundles, may in this case also lead us to suspect that thenbsp;genus would more rightly find its place here among plants resembling

gt; Brongniart (1), vol. ii, t. 8. nbsp;nbsp;nbsp;� Unger (5).nbsp;nbsp;nbsp;nbsp;* Unger (.5), t. 12, f. 4.nbsp;nbsp;nbsp;nbsp;* Unger (5), t. 12,

ff. I, 2. nbsp;nbsp;nbsp;* Unger (5), t. 12, ff. 6, 7.nbsp;nbsp;nbsp;nbsp;* Dawson (1), vol. ii, p. 126.nbsp;nbsp;nbsp;nbsp;� Unger (5), t. to, f. n.

Lycopods; but this cannot be determined without study of the original preparations.

A series of very dubious remains from the Devonian and Carboniferous deposits of North-Eastern America has recently been grouped together bynbsp;Dawson ^ under the name Ptilophyton, Daws. Hall has described the samenbsp;objects as hydroid polypes and given them the name Plumalina; innbsp;Lesquereux^ they are called Trochophyllum and are appended to Cala-mariae. The species first discovered, Ptilophyton Vanuxemi, Daws., whichnbsp;had been already figured by Vanuxem appears in Dawson�s earlier publications ^ as Lycopodites Vanuxemi, and with it a form from the Lower Coal-measures of Canada as L. Plumula�. This author also introduces into hisnbsp;genus L. pennaeformis � from the Millstone Grit of Altwasser in Silesia,nbsp;which is known in one piece only and is of a very questionable character.nbsp;The specimen unfortunately was not to be found for the moment, when Inbsp;was in Breslau. Little can be gathered from Dawson�s and Lesquereux�snbsp;somewhat rough figures; specimens of the American forms do not appearnbsp;to have reached Europe. These are thin branches with a striated surfacenbsp;and crowded verticillate scars: and on these branches and on both sides ofnbsp;them are linear leaves (?) which are still in situ and very nearly form a rightnbsp;angle with the branch, and which in the drawing of Ptilophyton lineare, Lesq.nbsp;look almost like the needles of Coniferae. Dawson it is true does not statenbsp;that the leaves are verticillate : he says � slender leaves in two or more ranks.�nbsp;The character of the surface in the stem figured by Lesquereux is strikinglynbsp;suggestive of the remarkable and little-known* Equisetum mirabile noticednbsp;above on p. 178, and it was this resemblance which led him to place thisnbsp;form with Calamariae. In conclusion, I must express my doubts as tonbsp;whether all these objects thus grouped together by Dawson do really belongnbsp;to one another; and I am confirmed in these doubts by the circumstancenbsp;that Lesquereux in the work in which he describes Trochophyllae reckonsnbsp;Lycopodites Vanuxemi ^ among Lycopodiaceae, with the remark it is truenbsp;� It may be an Encrinite,� without thinking of comparing them.

The statements respecting fossil remains of the family Psilotaceae are few and uncertam, nor is this surprising in such simple and slightly differentiated forms. If Psilotites lithanthracis� and Ps. unilateralism do reallynbsp;belong to this group, a point which I am unable to determine from thenbsp;figures, we should be able to follow the type as far down as the period ofnbsp;the Coal-measures.

It has become more and more a settled practice with palaeontologists and botanists to unite the genus Psilophyton with Psilotaceae Dawson

� Dawson (1), vol. ii, p. 119. nbsp;nbsp;nbsp;* Lesquereux (1), p. 63.nbsp;nbsp;nbsp;nbsp;� Vanuxem (1).nbsp;nbsp;nbsp;nbsp;* Dawson

(1), vol. 1, p. 35. nbsp;nbsp;nbsp;5 Dawson (7), p. 24; t. i, ff. 7-9.nbsp;nbsp;nbsp;nbsp;� G�ppert (19), p. 5��! t. 42.

� Lesquereux (1), p. 362. nbsp;nbsp;nbsp;* Goldenberg (1), t. 2, f. 7.nbsp;nbsp;nbsp;nbsp;� Kidston, 3. Dawson (1), (5), (0).

himself inclines to this comparison, though elsewhere� he conceives of these plants as �synthetic or generalised plants,� such as G�ppert meant by hisnbsp;prototypes, which unite the characters of Lycopodiaceae and Ferns. Nownbsp;this would be all very right and good, if we could have more clear and exactnbsp;information about these characters. Dawson�s description of the genusnbsp;rests chiefly on the impression made upon him in his repeated researches atnbsp;the localities where the fossils are found, especially Gasp�. Of the correctness of this impression in kind and degree we, who are dependent on thenbsp;few and as a rule ill-preserved specimens in European collections, are thenbsp;less able to judge, because Dawson unfortunately gives no exact descriptionnbsp;of individual specimens, though it is this which is so needful, but puts us offnbsp;with an account of the general idea which he has drawn from his study ofnbsp;them. The botanist cannot possibly feel inspired with any great confidence,nbsp;when side by side with better specimens of Psilophyton in the collectionsnbsp;at London, Stra.ssburg or Gottingen he sees others named by Dawson himself, which appear to him to be quite undeterminable remains of some kindnbsp;of leaf-stalk. Dawson ^ has determined as Psilophyton princeps and Ps.nbsp;robustius numerous remains in the collection at Edinburgh, which accordingnbsp;to Peach are common in the Middle Devonian beds of Scotland but havenbsp;been hitherto generally taken for � fucoids or roots.� Considering thenbsp;inclination at the time to determine fossil objects from these older formations, these remains must certainly have been regarded as very formlessnbsp;things. Nor is the comparison with Eophyton, Torell� (see on p. 46) verynbsp;reassuring. There is only one of Dawson�s species of Psilophyton whichnbsp;supplies real tangible characters, namely Ps. princeps, which is found innbsp;many localities in Canada and New Brunswick in the entire series of formations from the Upper Silurian to the Upper Devonian. I have seen severalnbsp;tolerably good specimens of this species, and they agree with Dawson�snbsp;figures The erect stems or branches have attached to them at a rightnbsp;angle somewhat numerous thorn-like processes, rudimentary leaves according to Dawson, and where these are wanting their point of attachment isnbsp;shown by a small ovoid scar. The upper end when preserved is bentnbsp;inwards in the shape of a hook or crosier, as in young fbrn-leaves. Thenbsp;branching is rather copious, sometimes plainly dichotomous with smallnbsp;divergence on the part of the daughter-members, elsewhere on the samenbsp;specimens apparently monopodial; we shall not be wrong in assuming thatnbsp;the development of the stem was sympodial. The delicate curved extremities, detached and looking like snail-shells, fill entire beds of slate at Gasp�.nbsp;The stems when fully grown show woody structure according to Dawson,nbsp;and their appendages are thorn-like and rigid. We have descriptions also

� Dawson (1), p. ^8. Dawson (1), vol. i, p. 77. Q), vol. i, t. y. * Dawson (5), p. 480.

of the horizontal creeping rhizomes, and figures of them from Dawson These when preserved in their natural position fill at Gasp� certain hardnbsp;beds of clay, as Stigmariae fill the underclays of coal-seams. They arenbsp;horizontal creeping stems with occasional bifurcations ; their smooth surfacenbsp;bears here and there small circular scars, from which roots proceed verticallynbsp;downwards and traverse the beds beneath. Unfortunately there is nonbsp;figure of a portion of rhizome attached to an evident stem of Psilophyton,nbsp;though the author states that he has seen entire plants two or three feetnbsp;long in connection. In his first publication^ Dawson figured an object ofnbsp;indefinite form having several lobes and attached laterally to a branch,nbsp;which he explained as the fructification of the plant. In the description henbsp;says of it, � Fructification probably in lateral masses, protected by leafynbsp;bracts.� Subsequently� the fructifications assume a totally different appearance. Small branches with repeated bifurcations, smooth and showing nonenbsp;of the distinctive features of the species, bear at their extremities groups ofnbsp;small stalked ovate-lanceolate bodies, sporangia according to Dawson,nbsp;which open, as he maintains, on one side by a longitudinal fissure. Notnbsp;only the character of this fructification, but its connection also with ournbsp;plant, is thus thoroughly obscure and doubtful. In one piece Dawson foundnbsp;anatomical structure preserved. The specimen in question is unfortunatelynbsp;not very fully described, and the figure ^ does not altogether agree with thenbsp;description of the rhizome to which the fructification was attached. Thenbsp;only transverse section of this specimen figured is oblique in its directionnbsp;and very imperfect It seems to contain a central vascular bundle-strand,nbsp;in which the presence of scalariform tracheides was ascertained, and whichnbsp;is said to be surrounded by a zone of � woody fibres.�

The other described species of the genus are in much worse case than Psilophyton princeps. The specimen figured by Dawson � as Ps. robustiusnbsp;looks like something very different, and indeed the author himself says thatnbsp;fragments of this species are scarcely to be distinguished from leaf-stalks ofnbsp;Ferns. Bodies of indefinite form set in bunches on the extremities of suchnbsp;stalks or of their lateral branches are supposed to be fructifications. Thisnbsp;form is said to be confined to the Upper Silurian formation. The figurenbsp;of Ps. glabrum in Dawson^ looks like a fragment of a branched leaf-stalknbsp;of some Fern ; that of Ps. elegaiis � shows only some irregular sinuousnbsp;lines. The same species appears in another and not much better figure �nbsp;made up of bundles of these hooked lines. And if the author himselfnbsp;admits so many quite undecipherable remains into his genus, it is not

^ Dawson (5), p. 479, and (1), vol. i, t. to. � Dawson (5). nbsp;nbsp;nbsp;� Dawson (1), vol. i. tt. 9, 10.

* Dawson (1), vol. i, t. 20, ff. 241, 242. nbsp;nbsp;nbsp;� Dawson (1), vol. i, t. ii, f. 134, and (10), p. 465 ;

t. 18, f. 22. nbsp;nbsp;nbsp;� Dawson (1), vol. i, t. 12.nbsp;nbsp;nbsp;nbsp;� Dawson (1), vol. i, t. 7gt; f- 79-nbsp;nbsp;nbsp;nbsp;* Dawson (1),

of the point of insertion of the leaves; it would be important to know whether this was surrounded or not by scale-leaves, as is the case in thenbsp;Conifers just mentioned. Though I have gone through the rich stores innbsp;the Museums of London, Oxford and Scarborough, I have unfortunatelynbsp;never succeeded in finding a single tuft of leaves with a distinct and well-preserved base. A second form also found near Scarborough and placednbsp;with Isoeteae is Solenites furcatus unfortunately known only fro'm somenbsp;scanty remains in not too good a state of preservation. In this spec'es thenbsp;linear leaves, which are only found singly, are repeatedly and dichotomouslynbsp;branched, and thus have a still greater resemblance to Czekanowskia. Thenbsp;suspicion of a nearer affinity between the two forms is strengthened by thenbsp;circumstance that both alike belong to the Lower Oolite formation.

surprising that he has found imitators. Thus two species, Ps. gracillimum, Lesq. and Ps. cornutum, Lesq., from the Silurian deposits of N. America,nbsp;have been described by Lesquereux and are fit associates of Dawson�snbsp;Ps. elegans. A fossil form from the Lower Devonian beds of Rhenishnbsp;Prussia was described by G�ppert^ in his time under the name of Hali-serites Dechenianus and placed among the Algae. Its delicate tufts ofnbsp;branches by their incurved hooked extremities recall Psilophyton princeps,nbsp;though they are quite smooth and have no lateral thorns. Dawson � firstnbsp;removed this form conjecturally to his Psilophyton, and Carruthers�� hasnbsp;since followed his example. The latter author has moreover added to thenbsp;same group certain fossils from the Devonian Sandstone of the north ofnbsp;Scotland, which were originally described as Lycopodites Milleri�, andnbsp;which if judged by the figures do in fact show some resemblance to Psilo-phytae. Carruthers names them Psilophyton Dechenianum, Carr., andnbsp;unites Haliserites with them. In like manner Sphenopteris Condrusorum,nbsp;Gilk., which has been already noticed, was first described by Cr�pin � as anbsp;species of Psilophyton. Lastly, as we are on the subject of these ancientnbsp;and obscure remains, we may mention here the very recently publishednbsp;Berwynia Carruthersii� from the Middle Silurian deposits of Corwen innbsp;Wales, which has been supposed to be the stem of a Lycopod of greatnbsp;dimensions. In spite of the good accompanying figure I would rather notnbsp;express any opinion respecting either this fossil, or Drepanophycus spini-formis * from the Upper Devonian Spiriferae-Sandstone of Hachenburg innbsp;Nassau, which to some extent resembles Berwynia.

Of the group of Isoeteae we know only two Miocene forms found at Oeningen and strongly recalling our Isoetes lacustris, for which it will benbsp;sufficient to refer the reader to Schimper �. Solenites Murrayana, Lindl. andnbsp;Hutt., from the Oolite of Scarborough, will be found noticed in the samenbsp;work as a doubtful form. This fossil has been excellently described innbsp;Lindley and Hutton It consists of long linear pointed leaves lyingnbsp;together in tufts and found in large numbers on certain slabs of stone.nbsp;According to the figure, the epidermis, which was brought out by treatmentnbsp;with nitric acid, is formed of irregularly angular cells, between which nonbsp;stomata were observed. This would certainly agree with the structure ofnbsp;the submerged Iso�tae; but fresh examination of the facts with the betternbsp;means now at our disposal is much to be desired, since the tufts of leaves innbsp;Solenites may quite as well be supposed to be short shoots of Conifers likenbsp;those of Phoenicopsis and Czekanowskia, and then stomata must certainly benbsp;found on the leaves. Something also might be gained from an examination

' Lesquereux (5). nbsp;nbsp;nbsp;^ Goppert (12), t. 2.nbsp;nbsp;nbsp;nbsp;^ Dawson (1).nbsp;nbsp;nbsp;nbsp;� Carruthers (9).

� Salter (1). nbsp;nbsp;nbsp;� Cr�pin (1).nbsp;nbsp;nbsp;nbsp;Hicks (2).nbsp;nbsp;nbsp;nbsp;� Goppert (12), t. 41, f. i. � Schimper (1).

The family of Lepidodendreae is one of the most conspicuous among those vegetable types which have become extinct in the course of geologicalnbsp;times. Like most of these types, it culminates in the Carboniferous period,nbsp;attaining its greatest development in the lower and middle divisions of thenbsp;Coal-measures \ Soon after that period it disappears, some scanty remainsnbsp;only being known from the Rothliegende. The furthest point to which thenbsp;group can be followed in the other direction is the lower portion of thenbsp;Devonian system, to which the schists of Wieda in the Harz are considerednbsp;to belong. These beds have produced two indubitable remains of Lepido-dendron, which were originally described by A. Romer ^ and have beennbsp;submitted by Weiss � to renewed and thorough examination. It is verynbsp;doubtful whether the two older Silurian remains, Protostigma sigillarioides'^nbsp;from the Cincinnati group of the Middle Silurian deposits and Glyptoden-dron eatonense � from the Clinton Limestone which forms the base of thenbsp;Upper Silurians, belong to Lepidodendreae. I must refer the reader to thenbsp;original publications for an account of these forms.

We are acquainted with a large number of stems, branches, leaves, and fructifications of Lepidodendreae, which are proved beyond doubt to havenbsp;belonged to one another by having been found attached to one another.nbsp;And if the group is here brought into immediate connection with Lycopo-diaceae, the reason for this arrangement is to be found not merely in thenbsp;habit of the organs of vegetation, but chiefly and emphatically in the structure of the cones of the fructification, which have been very carefullynbsp;studied and which positively exclude a closer alliance with any othernbsp;family. We shall return to this subject, as well as to the anatomy of thenbsp;organs of vegetation, in a subsequent page.

The surface of the stem when well preserved, as it very often is, presents a highly characteristic appearance, and hence Lepidodendrae came to be noticed by authors as early as the eighteenth century, by Volkmann'^

for example and Walch and can be recognised from their figures. It is entirely covered with elongate-rhomboidal flatly conical cushions whichnbsp;touch one another, and each cushion bears a detachment-scar at its mostnbsp;elevated point. This scar answers to the place of separation of a leaf,nbsp;the whole cushion to the decurrent leaf-base which has remained on thenbsp;stem. In the crowded position of the cushions which are everywhere innbsp;contact with one another the parastichies are very clearly shown, as in fircones, and careful study of them discloses very complicated conditions innbsp;the arrangement of the leaves. In the large stem of Lepidodendron Stern-bergii preserved in the Museum at Prague, Max Braun found that thenbsp;phyllotaxy wasnbsp;nbsp;nbsp;nbsp;Elaborate researches into the phyllotaxies which

occur in Lepidodendreae have been made by Naumann� and Stur'^. From these it appears that the complicated succession of many-membered cyclesnbsp;with definite divergences, which are exceptional in fir - cones but arenbsp;frequent in Lycopodiaceae, are the rule in Lepidodendreae, and that simplenbsp;spiral arrangement is seldom observed. The latter was found by Stur � innbsp;Lepidodendron Haidingeri with the divergence : two-leaved whorls occurnbsp;in L. Veltheimianum with the divergence and three-leaved whorls innbsp;the same species with the divergence = five-leaved whorls with thenbsp;divergence //g- and seven-leaved whorls with the same divergence werenbsp;ascertained in Ulodendron commutatum. From Stur�s original account wenbsp;may learn how he overcame the difficulty arising from the circumstance,nbsp;that the entire circumference of the stem is not usually open to examination.

Stur � has also given an elaborate description of the single cushion in all its details. The lateral angles of its rhombic outline are obtuse and thenbsp;Upper and lower angles are acute, and hence it is seen to be boundednbsp;by two lateral sinuous lines. It is separated from the eight adjoiningnbsp;cushions either by broad flat strips, or only by .sharp linear furrows. Innbsp;the latter case the bases of the leaves are in immediate -contact with onenbsp;another, in the former they are divided from one another by narrow portions of the smooth surface of the stem. How far this circumstance depends,nbsp;as Stur thinks, on differences in age, or to what extent it is due to specificnbsp;distinctions, I would prefer to leave undecided. The specimens with broadnbsp;intermediate strips are in his opinion younger plants; by further archingnbsp;over of the cushions the interstices between them were depressed andnbsp;became continually more like furrows, the narrow intermediate strips beingnbsp;more and more covered over and withdrawn from observation. The scar,nbsp;from which the leaf-blade separated, occupies the highest point in thenbsp;flatly pyramidal cushion. It varies in size and is transversely rhombic in

because he sees in them the secreting extremities of small branches of the vascular bundle which runs through the leaf-cushion. I should rathernbsp;compare them with the orifices^ which are found variously disposed on thenbsp;base of the leaf-stalks of tree-ferns. But I believe that it will be best tonbsp;refrain from all hypotheses with respect to this point, and to wait till wenbsp;have gained the needful light from the anatomical examination of a well-preserved stem-surface. There are still two other distinct marks to benbsp;mentioned, which are inserted in the course of the median upper ridgenbsp;separating the two upper facets of the cushion, and which Stur was thenbsp;first to notice with the proper attention. One of these marks is closenbsp;to the upper angle of the scar, and forms in all cases according to Stur anbsp;slight depression in the coal of the leaf-cushion; it is triangular in shape,nbsp;with the point directed upwards. It must therefore be always seen on thenbsp;mould as a small protuberance. Nevertheless I have before me a particularly well-preserved mould of a forked stem belonging probably to Lepido-dendron G�ppertianum which I found in the Dutweiler mine near Saar-briicken, in which this mark appears as a deep pit-like depression. I mustnbsp;presume therefore that a change has taken place in this object similar tonbsp;that which affects the trace-points in the lower faces. And when Stur appealsnbsp;to Selaginella and considers this pit to be the Hgular pit of Lepidodendron,nbsp;the comparison is perhaps a jpst one, for the position does in fact agreenbsp;with that of the ligule in Selaginella. But no proof can be adduced for ornbsp;against this view, and both the absence of a ligula in Lycopodium andnbsp;the resemblance between the small trace and other small scars in thenbsp;cushion suggest caution, and make so wide an interpretation of minute factsnbsp;appear too imaginative. The second spot which is situated on the mediannbsp;Upper corner occupies the very uppermost angle of the leaf-cu.shion ; it isnbsp;raised and prominent, and like the other js triangular in form. Stur sees innbsp;it a rudimentary indication of fhe point at the base of the leaf, on whichnbsp;the sporangium is seated in the fertile leaves of Iso�tes and Selaginella.nbsp;As this view is simply the logical consequence of the hypotheses justnbsp;described, it stands or falls with them. The object of the present worknbsp;does not require us to discuss the distribution into numerous species, whichnbsp;is chiefly founded on the form of the cushion and the position of the scar.nbsp;Figure 19, A and D, will illustrate the above remarks.

Hitherto we have been engaged exclusively with the character of the �Surface of the stem in a perfect state of preservation. But specimens ofnbsp;U�ipressions are very frequently met with which have a different appearance,nbsp;und these were consequently grouped together by the older authors undernbsp;quot;distinct genera ; but further research has had the result of showing withnbsp;greater or less certainty that these forms are nothing more than states ofnbsp;preservation of stems of Lepidodendron. In the case of most of them thisnbsp;view is generally accepted at the present day, and the old generic names

form, and in very many Cases through the opening out of the lower angle of the rhomb it approximates to an equilateral triangle with one angle atnbsp;the upper end. In normal circumstances its lower corner nearly coincidesnbsp;with the point of intersection of the diagonals of the rhombic cushion ornbsp;lies a little above them. On its flat surface near the lower margin threenbsp;marks are seen, which in casts are depressed, in moulds, where they arenbsp;usually very conspicuous, are strongly protuberant. They may be all ofnbsp;the same shape and dot-like, but in some cases the lateral ones are elongatenbsp;and linear, and the middle one only is either punctiform, or triangular withnbsp;one angle at the lower end and the sides prolonged and in the shape of anbsp;V. Nothing is 'more natural than to see in these three marks the points ofnbsp;severance of the leaf-trace bundles, and this is the view of most authors.nbsp;But since we know from Renault�s ^ observations on analogous conditionsnbsp;in Sigillariae that in these plants only the middle mark really answers tonbsp;the transverse fracture of a vascular bundle, while the lateral marks represent a different point of structure, it will be well to assume provisionallynbsp;that this is the case also in the group before us ; but the matter will havenbsp;to be considered again more fully in dealing with Sigillaria. At present wenbsp;have in fact nothing to go upon but such a conclusion from analogy,nbsp;because examination into the anatomy of Lepidodendrae has as yet thrownnbsp;no light on the question.

Both the area of the scar and the outline of the leaf-cushion represent transverse sections of a four-sided pyramid, and the angles of both arenbsp;therefore connected by projecting edges which divide the surface of thenbsp;cushion into four laterally disposed segments, the faces of the pyramid. Thenbsp;median ridges running in a straight line are more strongly marked than thenbsp;lateral ones ; the lower one is generally longer than the upper, because thenbsp;scar has been moved a little out of its position in the upward direction.nbsp;They bisect the upper and the lower acute angle of the rhomb. Each ofnbsp;the lateral edges on the other hand, running a little obliquely downwardsnbsp;from the lateral angles of the scar, divides the latei'al angles of the rhombicnbsp;cushion into an upper more acute and a lower less acute angle. In well-preserved specimens the facets may show a delicate velvety punctation ofnbsp;their entire surface, caused probably by the impression of the individualnbsp;epidermis-cells ; in some species they are marked with transverse folds andnbsp;wrinkles, which are sometimes Very prominent. Again, in the upper anglenbsp;of each of the two lower and larger facets, and near the median ridgesnbsp;which separate them, there is usually a conspicuous roundish or ovatenbsp;depression, which may however sometimes appear as a projection. Sturnbsp;proposes to call both of these marks the vascular glands of the leaf-cushion,

are given in Schimper ^ as mere synonyms of Lepidodendron. But as some states of preservation have a different appearance from the rest, doubts arenbsp;still expressed as to whether they are derived from one and the same genusnbsp;of plants. In answer to this I would call attention once more to the factnbsp;which was considered in the introductory chapter, that we must necessarilynbsp;see the remains of the same species under a quite different form, if it isnbsp;composed of portions of tissue of different power of resistance, since thesenbsp;must have been affected by external influences in a different manner innbsp;each case. A stem of this kind will have an entirely different appearancenbsp;in the fossil state if it rotted first of all on the damp ground in a forest, ornbsp;was covered by water while still fresh, or if it was exposed to the two kindsnbsp;of influence several times in succession. And that the first-mentioned condition, the presence of tissues of different power of resistance, was notnbsp;wanting in Lepidodendrae is shown by the anatomy of these plants, whichnbsp;will be considered presently. We may notice first the form described bynbsp;Sternberg ^ as Aspidiaria, Presl, which he had himself previously unitednbsp;with Lepidodendron (Fig. 19, A). G�ppert � has already given a completenbsp;explanation of the mode of formation of these Aspidiariae, and his descriptions have been fully confirmed by O. FeistmanteL, and again reviewed atnbsp;length by Stur �. When the cortical covering of the stem is removed, thenbsp;cushions seen from the inside form rhomboidal depressions ; whether thisnbsp;was in consequence of the perishing of their delicate central tissue, ornbsp;because, as Stur thinks, there was a central lysigenetic intercellular spacenbsp;traversed by a vascular bundle formed already during the life of the plant,nbsp;as in living heterophyllous Lycopodieae, is a matter of indifference andnbsp;cannot be determined. These hollows are filled up with the stony material, and in this way flat or slightly convex lozenge-shaped areolae arenbsp;formed, which without further structure show the trace of the emergingnbsp;foliar bundle as a dot-like protuberance or an irregular central longitudinalnbsp;elevation, while nothing can be seen of the lateral traces. If the trace innbsp;Aspidiaria is seen in the middle of the cushion, somewhat deeper thereforenbsp;than in the surface-picture of Lepidodendron, this is connected with thenbsp;ascending course of the bundle, for owing to this, the trace will appear in anbsp;lower position in proportion as the surface of the cylinder bearing the impression is further removed from the outer surface of the stem. By suitablenbsp;treatment of his specimen Stur has succeeded in extracting single rhombsnbsp;which filled the cavities, and by this means the surface of the leaf-cushionnbsp;was disclosed to view in its normal condition (Fig. ig, A). Schimper � givesnbsp;the figure of an Aspidiaria which is said to belong to Lepidodendron acule-

1 Schimper (1). nbsp;nbsp;nbsp;^ Sternberg, Graf von (1), Heft 1-4, t. 28, and Heft 5-8, t. 68.nbsp;nbsp;nbsp;nbsp;^ G�ppert

12), p. 48. nbsp;nbsp;nbsp;* O. Feistmantel (3), p. 207; t. 40, f. i.nbsp;nbsp;nbsp;nbsp;^nbsp;nbsp;nbsp;nbsp;p_nbsp;nbsp;nbsp;nbsp;f. 4,

atum, Stbg, in which the entire leaf-trace of the scar is depicted, but this is no doubt a mistake. Similar pictures are produced, when the rind ofnbsp;coal remains in the mould of the surface The cast, stripped of this rindnbsp;and coinciding with the boundary between two layers of parenchyma ofnbsp;different character, is in this case usually furnished only with small slightlynbsp;raised elongate-linear protuberances as indications of the leaf-bundles.nbsp;Casts of this kind are found in very extraordinary abundance. Casts arenbsp;described in Sternberg ^ as Bergeria, Presl (Fig. 19, B, C), the surface ofnbsp;which agrees exactly with that of a Lepidodendron when deprived of itsnbsp;epidermis ; some at least of these casts have belonged to a Lepidodendron,nbsp;as is seen from L. diplotegioides as reproduced by Schimper � afternbsp;LesquereuxThey show raised rhombic cushions separated from one

another by narrow intervals ; the bundle-trace is seen as a depression at the point of highest elevation. In the examples of this state of preservationnbsp;figured in Sternberg the emergence of the vascular bundle is extremelynbsp;close to the upper angle of the area of the cushion ; the difference in sizenbsp;between the upper and lower faces in these forms must have been verynbsp;pronounced (Fig, 19, B). At the same time the two diagonals of the cushionnbsp;are of nearly the same length, its outline approaching the form of anbsp;square. To this group undoubtedly belong several remains figured bynbsp;Schmalhausen * from the Ursa zone of Bear Island in Siberia, and also Lepidodendron tetragonum from the Coal-measures of Saxony�. O. Feist-mantel�s remarks on this point should be referred to ; this author considersnbsp;Bergeriae to be states of preservation both of Lepidodendron and of thenbsp;genus Lepidophloios which will be noticed presently, and he may be quite

^ G�ppert (19), t. 39, f. 2, nbsp;nbsp;nbsp;� Sternberg, Graf von (1), t. 6S, ff. 16-19.nbsp;nbsp;nbsp;nbsp;� Schimper (1),

t. 60, f. 7. nbsp;nbsp;nbsp;� Lesquerenx (1),nbsp;nbsp;nbsp;nbsp;� Feistmantel (1), HI.nbsp;nbsp;nbsp;nbsp;� Sternberg, Graf von (1).

Stur (5). nbsp;nbsp;nbsp;� Schmalhausen (iJ), t. 2, f- 5-nbsp;nbsp;nbsp;nbsp;^ Geinitz (8), t. 3, ff. i, 2, and Schimper (1),

right in this view, though the proof of it cannot at present be produced. Carruthers ^ also has expressed the same opinion. Lepidodendron nothum ^nbsp;again from the Cypridina-schists of Saalfeld appears to be similar in character, as are also certain bits of stem from the Upper Devonian and Lowernbsp;Carboniferous strata of South Australia and Queensland, which have beennbsp;described as L. australe, M^Coy � and as L. nothum, Ung. by Carruthers^nbsp;and O. Feistmantel� (Fig. 19, C). The figures themselves show that thenbsp;original surface is wanting in all these specimens, and I have besides assurednbsp;myself of the fact from numerous specimens from Queensland which arenbsp;preserved in the British Museum. If indeed the remains figured by Carruthers� in the work cited below and described by him as leafy branches,nbsp;which unfortunately I did not see, really belong to this group, then we may

be dealing here with a genus distinct from Lepidodendron and agreeing withnbsp;it only in certain states of preservation.nbsp;Carruthers unites with his Lepidodendronnbsp;nothum, Ung. a Devonian fossil fromnbsp;Canada and Maine which Dawson � hadnbsp;described as Leptophloeum rhombicum,nbsp;and to all appearance he is right innbsp;doing so ; it may differ, if at all, onlynbsp;in the somewhat deeper position of thenbsp;vascular bundle-trace, for the Artisia-pith which is appealed to by Dawson,nbsp;who protests loudly against Carruthers�snbsp;opinion, is more than uncertain and looksnbsp;in his figure merely as an indefinite crossnbsp;striation. Artisia-cylinders are it is truenbsp;claimed by Corda also as belonging tonbsp;Lomatophloios a genus of Lepidoden-dreae, but these cases also are quitenbsp;doubtful on other grounds; they havenbsp;hitherto been regarded with certainty as stems and branches of Cordaiteae.

With regard to the genus Knorria, Stbg (Fig. 20), which must .now be considered, authors are much divided in opinion ; we know however that itnbsp;represents an inner subepidermal state of preservation of lepidodendroidnbsp;plants. The frequent dichotomies, which will be further noticed below,nbsp;prove that it cannot belong to Coniferae, as Sternberg its first describer,nbsp;believed. It was then regarded as a proper and well-characterised genus of

� Carruthers (12). nbsp;nbsp;nbsp;^ Unger (5).nbsp;nbsp;nbsp;nbsp;� O. Feistmantel (1), ui, t. 13.nbsp;nbsp;nbsp;nbsp;* Carruthers (10),

t. 26. nbsp;nbsp;nbsp;� O. Feistmantel (1), in, tt. i, 14.nbsp;nbsp;nbsp;nbsp;� Carruthers (10), t. 26, ff. 1, 2.nbsp;nbsp;nbsp;nbsp;� Dawson

(1), vol. 1, p. 36, ff. 88, 89, and voh ii, p. 105. nbsp;nbsp;nbsp;* Sternberg, Graf von (1), Heft 1-5, t. 27.

the group which we are considering, till Goppert, who had at first taken up the same position came forward in support of the view that it belongs asnbsp;a cast-form to species of Lepidodendron He cites Lepidodendron Velt-heimianum and Knorria imbricata as forms which belong to one another,nbsp;and tries to prove this by figuring numerous specimens. His ideas havenbsp;met with much assent, but they have not been able to triumph over allnbsp;doubts. Schimper� both before and since has taken the opposite view,nbsp;and so has Heer^; and Weiss � has recently spoken doubtfully and cautiouslynbsp;on this point, resting chiefly on the fact that the Knorriae which are scattered through the Devonian system and are abundant in the Culm arenbsp;scarcely, if ever, found in the higher members of the Carboniferous formationnbsp;which are full of Lepidodendrae, but are replaced by Aspidiariae and Ber-geriae. He concludes from this�, � that at all events it is not every Lepidodendron that has a Knorria for a cast.� Many figures of Knorriae are to benbsp;found in the works quoted, in Schmalhausen ^ and in Schimper In thenbsp;typical state the entire surface of the stem is occupied by spirally disposednbsp;protuberances running a greater or less distance down the stem, and endingnbsp;above in a conical point pressed close to the stem but .separated from it bynbsp;a sharp furrow; at the extremity of this point when the preservation is verynbsp;good is a depression, deeper or shallower as the case may be, which is considered by all authors, and not without reason, to contain the scar-tracenbsp;of the foliar bundle. The length and shape of these leaf-cushions, theirnbsp;acute or more obtuse terminations, their looser or more crowded arrangement, their greater or less convexity were then used to distinguish a largenbsp;number of species in the genus, but these have been all finally united againnbsp;by Goppert � in one category as states of preservation of a few Lepidodendrae,�Lepidodendron Veltheimianum, and L. aculeatum. In this proceeding he relies especially on two fragments from the quarries of Landshutnbsp;in Silesia, the different faces of which he has figured from photographs iquot;.nbsp;One of these specimens certainly shows quite different leaf-scars on variousnbsp;parts of its circumference, some of which represent a typical Knorria, thenbsp;others a Bergeria, though in a rather rough state of preservation. As thenbsp;narrow fissure between the conical terminations of the leaf-cushions innbsp;Knorria and the surface of the stem is filled with a rind of coal, certainnbsp;portions of tissue have been preserved in this case on the upper side of thenbsp;cushion when the cast was made, which had disappeared by that time innbsp;the places where we see scars of Bergeria. Another specimen, that ofnbsp;Knorria princeps figured by Goppert which I have had opportunity of

an essentially different appearance in the remains which Ettingshausen ^ connects with this species, and are almost equal in length to those of L.nbsp;longifolium, Brongn., with which Schimper places them. Fine branchesnbsp;with broadly lanceolate leaves are described in the same publication ofnbsp;Ettingshausen as L. Haidingeri and others with short linear leaves as L.nbsp;brevifolium, Ett.� Lastly, the name L. selaginoides, Stbg is given bynbsp;authors to certain portions of branches with many ramifications, which arenbsp;furnished with short leaves incurved and hooked after the manner of Arau-cariae or Walchiae. I have found such leaves in great abundance nearnbsp;Saarbr�cken, and particularly fine specimens of them occur in the clay-ironstone nodules of Coalbrook Dale in England ; figures of them will benbsp;found in BrongniartO. FeistmantelLindley and Hutton�, and Schmal-hausen''. The forms known as Lepidophyllum and regarded by Stur asnbsp;foliage-leaves of Lepidodendron will be noticed again in a subsequent page.

But it is not only in the form of the leaves that the foliage-branches which have been described differ from one another; the leaf-bearing axesnbsp;themselves vary much in character. Some are stiff, little or not at allnbsp;branched, and of remarkable thickness, as for example in Ettinghausen�snbsp;Lepidodendron brevifolium, L. Sternbergii, and L. Haidingeri; others arenbsp;thin and slender like so many rods, and are then usually copiously branchednbsp;with repeated bifurcations, as is the case in general with the forms namednbsp;Lepidodendron selaginoides. It cannot be doubted that these differencesnbsp;indicate important variations in the construction of the entire head of thenbsp;trees, which in the latter case may have been copiously and denselynbsp;branched with the terminal ramifications occasionally pendulous, while innbsp;the other case its branches may have been stiff, open, and few in number.nbsp;And this leads to the consideration of the mqrphological building up of thenbsp;entire plants, of which we have hitherto been discussing the separate parts.nbsp;In numberless cases, as has been observed more than once before, both innbsp;evident Lepidodendrae and in Knorriae also, we can point to clearly ascertained dichotomies, which repeat themselves sometimes in larger fragmentsnbsp;in the successive branch-generations. For this we may appeal to thenbsp;figures already cited. As frequently, and usually on the same pieces withnbsp;the dichotomies, we find lateral branching also variously distributed. Casesnbsp;of this kind may in wonted measure and following the opinion of authorsnbsp;be explained by assuming sympodial development of the dichotomousnbsp;systems, though it seems scarcely necessary to have recourse to this method,nbsp;now that we know that the two forms of branching are present side by sidenbsp;in Psilotum, that in fact thei-e is no fundamental difference between them.

' von Ettingshausen (5), tt, 26-28. nbsp;nbsp;nbsp;* von Ettingshausen (5), t. 22.nbsp;nbsp;nbsp;nbsp;= von Ettingshausen (5),

t. 25. nbsp;nbsp;nbsp;�* Brongniart (1), vol. ii, t. 17.nbsp;nbsp;nbsp;nbsp;� O. Eeistmantel (3), tt. 30, 31.nbsp;nbsp;nbsp;nbsp;� l.indley

and Hutton (1), vol. i, t. 12. nbsp;nbsp;nbsp;� Schmalhausen (2), t. 2, ff. 5, 6.nbsp;nbsp;nbsp;nbsp;*

In the Knorriae, in which this lateral branching is particularly common, the thinner lateral branch will often impede the further growth in thickness ofnbsp;the main stem, and then the base of the side-branch is seen to be imbeddednbsp;in a lateral groove which forms on the stem. The branch is then usuallynbsp;found to be broken short off, and the appearance is sometimes as thoughnbsp;this fracture took place before the specimen was imbedded in the stone;nbsp;this is the case when the lateral furrow terminates suddenly with a curvednbsp;outline just above the place of fracture, and the stem at once recovers thenbsp;original form of the transverse section.

Though such large portions of the head of Lepidodendrae have come under observation, yet, as might be expected, it is only in a few cases thatnbsp;the main ramifications have been seen attached to the stem which borenbsp;them. From these few discoveries it cannot be distinctly gathered, whethernbsp;the considerable differences have specific or only individual significance;nbsp;still they are so strong that we necessarily incline towards the former view.nbsp;Among the first stems which have a claim to precedence of notice is thenbsp;one described by Lindley and Hutton^ as Lepidodendron Sternbergii.nbsp;It was discovered in the roof of a seam in Jarrow mine in England, andnbsp;was laid bare from the base to the branches of the crown, a length ofnbsp;thirty-nine feet. The stem, which is three feet thick in its lower portion, isnbsp;flattened, and, if I understand the accounts propei'ly, shows the Bergeria-character on the surface. It branches dichotomously in the most regularnbsp;manner, and its crown is preserved through three generations of bifurcatingnbsp;shoots, but is then broken off by a small fault. In Sternberg�s ^ famous stem,nbsp;on the other hand, which was discovered in the roof of the lower Radnitznbsp;seam at Svinna in Bohemia and with its branches is four metres in length,nbsp;the crown begins with two branches placed exactly laterally right and leftnbsp;and at a distance of forty-six centimetres from one another; we knownbsp;nothing of their subsequent ramifications, as they are broken off near thenbsp;base. The first regular bifurcation is forty-six centimetres further downnbsp;the stem, and this is repeated twice in the branches and then passes intonbsp;lateral branching. We are indebted to Stur � for the description of a thirdnbsp;case. The colossal stem, five hundred and twenty-two centimetres innbsp;length and sixty-three centimetres in diameter at the bottom, had had itsnbsp;head broken off down to the lowest and exactly lateral branch; it wasnbsp;found in the Alberti mine at Hruschau in Bohemia, and was carefullynbsp;drawn as it lay. The one branch, which is thirty-one centimetres innbsp;diameter at the point of attachment and narrows rapidly, forms a rightnbsp;angle with the stem and shows sympodial branching.

named Ulodendron since Sternberg�s time. Their distinguishing feature is the presence on their outer surface, which is covered with Lepidodendron-cushions, of two opposite vertical rows of enormous usually depressednbsp;platter-shaped or cup-shaped scars, which may be either crowded togethernbsp;till they touch one another, or be separated by wider intervals within eachnbsp;row. The Ulodendron-character is usually seen in strong thick stems, innbsp;which branching is an extremely rare occurrence ; but Williamson ^ hasnbsp;described one case of the kind, in which one of the large cup-shaped scarsnbsp;lies exactly in the angle between the members of the dichotomy. It is notnbsp;often that these stems are found with the surface-characters clearly shown ;nbsp;they are usually observed in the form of interior casts, on which thenbsp;position of the leaves is shown by the small linear protuberances due tonbsp;the trace-bundles. The Ulodendrae have recently been submitted tonbsp;careful examination by Stur Kidston and Zeiller �*. In Kidston will benbsp;also found a very complete collection of the older literature. The authorsnbsp;just cited, though differing in their views on other points, all agree innbsp;thinking that the stems in question show variations in the character of theirnbsp;surface, and may accordingly be divided into three groups. We willnbsp;confine our attention for the present to the first of these groups, whichnbsp;shows an almost absolute agreement with the normal and well-knownnbsp;Lepidodendron Veltheimianum, while the remains contained in it arenbsp;usually named Ulodendron commutatum, Schpr., and are directly unitednbsp;with that species by the authors just mentioned The leaf-cushions innbsp;specimens of Ulodendron are however as a rule considerably smaller thannbsp;those of ordinary Lepidodendron-stems of equal thickness, though theynbsp;agree wuth them in other respects. If we examine the peculiar plattershaped or cup-shaped scars, we find that they are roundish, elliptic ornbsp;ovate, and more or less deeply depressed, and that they appear thereforenbsp;on the mould as a convex projection ; a somewhat sharp edge forms theirnbsp;boundary line. At the deepest point is a nearly circular scar of separation,nbsp;in the middle of which a dot-like trace may still be seen when the state ofnbsp;preservation is sufficiently good. This point of separation is not howevernbsp;central; it can always be seen, more or less distinctly, to be pushednbsp;towards the lower side of the cup, so that the slope on that side is steepernbsp;and the radii shorter than on the upper side. The whole surface of thenbsp;slope surrounding the scar bears small keel-like protuberances arrangednbsp;pretty nearly in radiating rows, which look like the leaf-trace-marks ofnbsp;poor interior casts of Lepidodendrae, and are apt to run together intonbsp;irregular and indistinct radial ribs, especially on the upper flatter slope ofnbsp;the platter. These stripes may be the only markings visible on the entire

' Williamson (1), x, p. 499. nbsp;nbsp;nbsp;^ Stur (5).nbsp;nbsp;nbsp;nbsp;^ Kidston (2).nbsp;nbsp;nbsp;nbsp;�gt; Zeiller (3) and (11).

Schimper (1), t. 63 ; Kidston (2), t. 3 ; Brongniart (1), vol. ii, t. 18; Star (5), tt. 21, 22, f. 3.

surface of the scar when the preservation is imperfect. Ulodendron-stems have occasionally been mistaken for stems of Megaphytum which have alsonbsp;two lines of scars (see above on p. 167), as the literature testifies, but suchnbsp;confusion is only possible where both the surface of the stem and the cupsnbsp;are very badly preserved, and may be avoided in most cases by carefulnbsp;examination of the specimens.

Now comes the question, what were the organs which were inserted on these scars. On this point a great variety of opinions finds expression in thenbsp;literature. Carruthers*, differing from all other authors, who look upon thenbsp;central circle only as the scar of separation of the lateral member andnbsp;explain the formation of the cup as the effect of the pressure of that member,nbsp;has tried to prove that the entire cup answers to the place of separation. Henbsp;considers the dot-like protuberances on its slope and the central scar also tonbsp;be vascular bundle-traces, and assumes the existence of strong adventitiousnbsp;roots springing from these places. Apart from the fact that no trace ofnbsp;such adventitious I'oots has ever been found, the anatomy of the organs isnbsp;most decidedly opposed to this view, as will be shown below. The idea ofnbsp;a root with a mass of cortical bundles as well as the central strand mustnbsp;seem to the botanist to be a priori open to objection ; and Kidston^ hasnbsp;supplied an excess of proof by describing and figuring a specimen in whichnbsp;the slope of the cups is covered with quite normal cushions of the leaves ofnbsp;Lepidodendron, and which is thus shown to be most certainly a segment ofnbsp;the surface of the stem. There remains therefore only the possibility thatnbsp;the scars in question bore vegetative branches or organs of fructification.nbsp;It is improbable that they bore vegetative branches, as Stur � has shownnbsp;against Geinitz^; the great objection to this view is the regularity of thenbsp;planes of separation, for which no analogue can be found except in thenbsp;cladoptosis of our forest trees, the oak for example. That such separationsnbsp;are at least not invariable is shown by the branching of Knorriae whichnbsp;was described above, in which the pressure of the stumps that are leftnbsp;causes the formation of lateral furrow's on the main stem. Thus we comenbsp;back to the most natural and oldest idea, that these scars are the places ofnbsp;separation of the fructifications. And here Stur has been led by a speculation, which in my judgment is quite unfounded, to a very remarkable result.nbsp;He sets out from the view that the surface of the stem is of exactly thenbsp;same character in Lepidodendron Veltheimianum and in Ulodendronnbsp;commutatum, and that the two must therefore be considered to benbsp;identical forms. As he knows that there were cones of fructificationnbsp;attached to the extremities of thin leafy terminal branches in Lepidodendron Veltheimianum, the scars on the thick stems could not possiblynbsp;have also borne cones. Vegetative branches are excluded for the reasons

already given. But since something must have had its place there, he proceeds to study living Lycopodiaceae in order to find an analogue for this something that is required. And so the bulbils of Lycopodium Selago andnbsp;L. lucidulum must be pressed into the service. The marks in Ulodendronnbsp;are thereupon declared to be the scars of bnlbils, of the nature of whichnbsp;the author ^ distinctly says that he knows nothing. And when he nevertheless endeavours to show that these hypothetical bulbils were developednbsp;in the axils of leaves by explaining a small irregularity in the arrangementnbsp;of the leaves, which was observed on a bit of stem as a young state of thenbsp;same, the arbitrary character of the assumption is so obvious that it neednbsp;not be submitted to closer examination. A specimen described bynbsp;Goldenberg, in which Stur thinks that he has seen the basal portions atnbsp;least of his bulbils, will be noticed again below, when the genus Lepido-phloios is under consideration. If we try in this way to pick out thenbsp;course of thought from among the many details of the account, the fallacynbsp;which is at the bottom of the whole theory comes out to the light of day.nbsp;I myself draw only this conclusion from the facts, that there were severalnbsp;forms of Lepidodendron with similar or the same sculpture on branchesnbsp;and stems, which differed however essentially in the position and mode ofnbsp;development of their cones. We have only to compare in reference to thisnbsp;point the living species Lycopodium annotinum and L. laterale fromnbsp;Australia. And since cones of fructification of the most various forms arenbsp;known in abundance and there are no examples of brood-buds, I take mynbsp;stand in this matter entirely on the ground of facts. It may be observednbsp;here that cases have recently become known, in which cones are stillnbsp;attached to the scars in Ulodendron. Such a case has been described bynbsp;Thompson though it would appear from the figure not to be entirelynbsp;beyond the reach of controversy. There is another specimen about whichnbsp;there can be no doubt, also found by Thompson near Edinburgh but not asnbsp;it seems yet published, which I saw some years ago when I was withnbsp;Williamson in Manchester, and which he has noticed incidentally*. Herenbsp;the cones are sessile and form cylinders of considerable thickness. Itnbsp;might therefore be expected that a pressure-surface would be formednbsp;between the cones and the stem which probably increased in thicknessnbsp;during their development, and it must have been cup-shaped to fit thenbsp;base of the cone. The place of separation will then be deeper and morenbsp;excentric in proportion to the acuteness of the angle which the cone formsnbsp;with the stem which bears it; nor can the displacement of the leaf-tracesnbsp;from their normal position in the cup-shaped scars cause any surprise innbsp;view of this mutual pressure.

The second group of branches with Ulodendron character comes nearest in surface-features to the Bergeria-forms with a deep-lying bundle-trace,nbsp;which were discussed above on p. 199, and which we have compared withnbsp;Dawson�s Leptophloeum. To this group belong for example Ulodendronnbsp;majus and U. minusStur�s figures^ which were classed by him with Lepi-dodendron Veltheimianum but can scarcely belong to it, and a few drawingsnbsp;of Carruthers � and Kidston The latter author refers all these forms without hesitation to the genus Sigillaria, uniting them with the two speciesnbsp;Sigillaria Taylori, Carr, and S. discophora, Koenig. But the only reasonnbsp;for this, as Zeiller� has well shown, is a certain resemblance in habit, anbsp;resemblance which has misled Goldenberg � also into figuring a fragmentnbsp;of Lepidophloios as Sigillaria Menardi. I do not know what it was thatnbsp;decided Stur to place, the two specimens mentioned above as -resemblingnbsp;Leptophloeum with Lepidodendron Veltheimianum. He found the shortlynbsp;lanceolate leaves still attached to one of them, and concluded from this^nbsp;that it was a young stem and that the leaf-scars were not yet developed.nbsp;Even this conclusion appears to me to be thoroughly rash, considering thenbsp;little knowledge which we possess respecting the development of the leafnbsp;and leaf-cushion. If Zeiller�s view is right, and it still requires confirmation,nbsp;the Leptophloeum-forms which we are considering would have retained theirnbsp;leaves a long time, and would have lost them at last by irregular fracture,nbsp;not by dismemberment. He mentions a piece of stem with excessively longnbsp;leaves from the mines of Lievin, in which the areolae of the broad bases ofnbsp;the leaves were quite like those of Ulodendron majus. I have some piecesnbsp;in my possession which make me think it probable that Leptophloeum maynbsp;represent a distinct genus, though one nearly allied to Lepidodendron. Butnbsp;much further research is needed for the clearing up of these questions.

The last type of ulodendroid stems is represented by Lindley and Hutton�s * genus Bothrodendron, which though impugned by Kidston hasnbsp;been successfully defended by Zeiller The most clearly ascertained speciesnbsp;of the genus is Bothrodendron punctatum (Ulodendron Lindleyanumnbsp;with large cups widely separated from one another, in which the scar is verynbsp;deep and very excentric. The surface of the stem is preserved in placesnbsp;on the layer of coal which covers the casts, and is extremely characteristic.nbsp;It is marked by the very feeble development of the base of the leaf, andnbsp;as consequently there was no formation of cushions it is quite flat andnbsp;even, being furnished only with small sinuous longitudinal wrinkles. Thenbsp;scars from which the leaves parted appear on it as small dots, separated

^ * Lindley and Hutton (1), vol. i, tt. 5, 6. nbsp;nbsp;nbsp;� Stur (5), t. 22, fif. 1, 2.nbsp;nbsp;nbsp;nbsp;^ Carruthers (11).

^ Kidston (2), t. 4, f. 5 ; t. ff. 8, 9; t. 7, f. 12. nbsp;nbsp;nbsp;� Zeiller (11).nbsp;nbsp;nbsp;nbsp;� Goldenberg (1), t. 7, f. i.

Stur (5), p. 288. nbsp;nbsp;nbsp;� Liiidley and Hutton (1), tt. 80, 81.nbsp;nbsp;nbsp;nbsp;� Kidston (2).

examining in the Museum at Breslau, has appeared to me to be of verj'-special importance in connection with this question. Here scars of a Lepido-dendron are plainly to be seen on the rind of coal preserved at one spot in the stem, so that this fragment virtually decides the matter as far as I amnbsp;concerned. Goldenberg^ also states that he has found Knorria Sellonii,nbsp;Stbg (the word should be written Selloi, as the species is named fromnbsp;Bergdirector Sello of Saarbr�cken) in the roof of the Auerswald seam atnbsp;Saarbrticken attached to indubitable rind of Lepidodendron. Unfortunatelynbsp;the figure which he has given of his specimen is not an exact and workingnbsp;one. Grand� Eury ^ is of the same opinion, though he has not given hisnbsp;reasons in full. He says only ^ : � From the observations of MM. Goldenbergnbsp;and G�ppert and from my own, the Knorriae are nothing more than the subcortical mould of Lepidodendreae, though this is not M.Schimper�s opinion;�nbsp;and further on, � A Knorria from St. Etienne with the tubercles prolongednbsp;into horizontal threads reflects the form of a deeper layer situated at a considerable distance from the rind.� It appears also from this passage thatnbsp;the form of preservation which we are considering is found also in the highernbsp;beds of the Carboniferous system, and is not confined to its lower portion.nbsp;But according to Heer'* the infra-Carboniferous Knorriae of Bear Island (thenbsp;Ursa zone), which have no doubt been correctly determined, are essentiallynbsp;different. He founds his view on a specimen figured in the work just cited�.nbsp;This is a portion of a cast covered with Knorria-scars with pointed extremities, and has its covering of coal still preserved here and there; and onnbsp;the outer finely-striated surface of the coal are comparatively diminutive circular scars at considerable distances from one another and with punctiformnbsp;remains of a central leaf-trace. It appears from the text that these smallnbsp;scars are placed in regular oblique rows, each appearing to answer to thenbsp;pointed extremity of the underlying tubercle. If this is so, then the figurenbsp;is incorrect, for there the regular rows can scarcely be perceived and thenbsp;scars in some places do not coincide with the extremities of the Knorria-cushions. The matter cannot be cleared up without fresh examination ofnbsp;the original specimen. If Heer�s statements are shown to be correct, wenbsp;shall then be forced to conclude that the surface of the stems which gavenbsp;rise to certain forms of Knorria was similar in character to that which wenbsp;find in the genus Bothrodendron, which will have to be considered presently.

Two other genera which take their place with Knorria have been described by G�ppert as Ancistrophyllum stigmariaeforme and Didymo-phyllum Schottini. A few specimens of them have been found in the Culmnbsp;of Landshut in Silesia, and subsequently in the same formation at Thannnbsp;in Alsace. In the latter species the Knorria-like cushions of the cast are

� Goldenberg (1). nbsp;nbsp;nbsp;^ Grand� Eury (1).nbsp;nbsp;nbsp;nbsp;= Grand� Eury (1), p. 144.nbsp;nbsp;nbsp;nbsp;* lieer (5),

vol. 21. nbsp;nbsp;nbsp;� Heer (5), vol. 2 i, t. 10, f. 4. 's G�ppert (1), Ljef. i and 2, tt. 17, iS.

shortly decurrent and loosely arranged, and have their extremities slightly emarginate ; the former appears in rather shapeless casts studded withnbsp;irregularly shaped pad-like protuberances which are broader in the transversenbsp;direction. Knorria Richterih also, from the hard coal of Oberhohndorf innbsp;Saxony, belongs to our present group, as its author expressly states.nbsp;Schimper, who has also given a figure of Ancistrophyllum showed subsequently � that the two genera are portions of the base of the stem of Knorrianbsp;longifolia ; he states that he found the characters of the three genera unitednbsp;in a stem discovered at Burbach near Thann. He refers the difference innbsp;shape of the remains of the leaf-cushions to changes connected with thenbsp;growth of the stem, which may have affected the outer form as well as thenbsp;inner structure. One more genus remains to be mentioned, Dechenia, G�pp.,nbsp;about which I refrain from expressing any decided opinion. Dechenianbsp;R�meriana, G�pp.^, from the Lower Devonian deposits, reminds us ofnbsp;Knorria; D. Euphorbioides� from the Culm of Landshut in Silesia is anbsp;rather shapeless approximately cylindrical piece of stone covered withnbsp;spirally disposed cushion-like projections.

Leafy branches of Lepidodendron are excessively abundant in the Coal-measures, and have essentially the habit of Lycopodiae. By thenbsp;disappearance of the leaves which drop off regularly, as they do not innbsp;Lycopodium, the characteristic leaf-cusliions are disclosed to view, and arenbsp;at first small, but subsequently follow the further growth of the stems andnbsp;branches, and increase in size. Little attention therefore is to be paid tonbsp;these cushions in determining the limits of the species ; and other changesnbsp;of form may possibly be connected with them of which we know little owingnbsp;to the fragmentary character of the material, and which may therefore benbsp;the source of fresh causes of error in defining species. For this reason thenbsp;statements of authors, that certain leafy branches must belong to certainnbsp;species which are known by the structure of the stem, must be acceptednbsp;with the greatest caution, since they scarcely ever rest on observation ofnbsp;the actual attachment of the branches to the pieces of stem to be determined. The leaves themselves are of very different size and shape; they arenbsp;flat, linear, and pointed, and of very considerable length in the branch figurednbsp;by Schimper � after R�hl and identified as Brongniart�s Lepidodendronnbsp;longifolium. Similar leaves, but much shorter and more strongly squarrosenbsp;and not collected into a parallel tuft, are drawn by Brongniart ^ in his Lepidodendron elegans and L. gracile, which are both referred by Schimper tonbsp;the collective species L, Sternbergii, Brongn. It is true that they have

� Geinitz (5), p. 39; t. 4, f. 2, nbsp;nbsp;nbsp;* Schimper (4), tt. Ii, 12.nbsp;nbsp;nbsp;nbsp;^ Schimper (1), vol. ii, pp. 58

and ji8. 4 4. Rijmer (1), n, t. 14, f. i. = G�ppeit (1), Lief. 3-4, t. 3. nbsp;nbsp;nbsp;� Schimper

T), t. 59, f. I. nbsp;nbsp;nbsp;7 Brongniart (1), vol. ii, t. 14 and t. 15, and Lindley and Hutton (1), vol. ii,

from one another by wide intervals ; according to Zeiller�s account they are polygonal with the lateral corners truncated, and show the characteristicnbsp;three trace-points. Close above them in all cases is the so-called ligular pit,nbsp;which is depicted by Zeiller as a diminutive circular scar. The genus appearsnbsp;unfortunately to be a scarce one; the only perfectly satisfactory well-preservednbsp;specimens that I have seen are in the collection of the �cole des Mines atnbsp;Paris. If indeed the flakes of cuticle pierced with small holes which formnbsp;the paper-coal of Tovarkova near Tula belong to Bothrodendron, as Zeillernbsp;endeavours to .show and as is indeed probable, the genus must have beennbsp;enormously developed in that locality very low down in the Carboniferousnbsp;formation on the horizon of the Carboniferous Limestone. In fact all ournbsp;specimens hitherto have come from the Lower Carboniferous deposits, ornbsp;at least from the bottom of the Middle series. And when we considernbsp;Heer�s statements noticed above on p. 2o% respecting the rind of certainnbsp;infra-Carboniferous Knorriae, we can scarcely avoid the conclusion thatnbsp;these are states of preservation of Bothrodendron. At Carvin, in thenbsp;Department of the Pas de Calais, Zeiller has also found leafy branches withnbsp;repeated bifurcations, which are proved by the leaf-scars on the older partsnbsp;to belong certainly to Bothrodendron. These branches bear very shortnbsp;almost scale-like acutely lanceolate leaves, which are in loose array andnbsp;show the smooth surface of the stem between them. Exactly similar stems,nbsp;which also have similar leafy branches but without the large Ulodendroidnbsp;cup-shaped scars, have been described by Boulay^ as Rhytidodendronnbsp;minutifolium ; a figure of the surface of the plant will be found in Zeillernbsp;According to Kidston these stems occur not only in the North of France,nbsp;but also in several parts of Scotland. It is natural to assume with Zeillernbsp;that there is a similar relation between Bothrodendron and Rhytidodendronnbsp;to that which has been shown to be probable between Ulodendron andnbsp;Lepidodendron. In both cases we should have the cones in different speciesnbsp;of the same type at one time on the stem and on the thicker branches, atnbsp;another terminal on the extremities of smaller branches.

Closely connected with the Ulodendron-forms, in the opinion of all authors, is the genus Lepidophloios to which Lomatophloios, Corda maynbsp;also be joined. Though this genus has been known for a long time, yet itnbsp;is greatly in need of fresh examination, for there are various points connected with it which are still obscure. The most thorough treatment of itnbsp;up to the present time will be found in Corda Goldenberg Weiss and O-Feistmantel *; Stur � also has occupied himself with it. The platter-shapednbsp;scars are quite similar in character to those of the remains which we havenbsp;been considering, but they are arranged on the stem in four lines instead of

' Zeiller (2). Boulay (1). nbsp;nbsp;nbsp;^ Zeiller (2), t. 9, f. 2.nbsp;nbsp;nbsp;nbsp;�* Sternberg, Graf von (1), Heft 1-4, p- I31

t. ii,ff. 2-4. nbsp;nbsp;nbsp;5 Corda (1).nbsp;nbsp;nbsp;nbsp;' Goldenberg (1).nbsp;nbsp;nbsp;nbsp;� Weiss (1).nbsp;nbsp;nbsp;nbsp;� O. Feistmantel (3). quot;StnrCS).

two, and the genus is further distinguished by the quite peculiar configuration of the leaf-cushions. These are not flat as in Lepidodendron, but are developed in the form of tall steep-sided cones which are crowded closenbsp;together and gird the stem with an armour of leaf-bases, just as in ournbsp;modern Cycadeae. In addition to this the base of the cushion is transversely rhombic in form, the angles at the lateral edges being acute andnbsp;those at the median very obtuse, and thus the cushions differ altogether innbsp;habit from the elongated cushions of Lepidodendron, and have the appearance of scale-like leaves. From their crowded position they necessarilynbsp;cover one another like the tiles in a roof; in looking at them from the outside we get sight of the anterior portion only of one pair of facets of eachnbsp;cushion, and the areola of separation of the leaf-blade lies on the mostnbsp;anterior point of its margin. This areola has a similar outline to that ofnbsp;the whole cushion, its lateral edges are very sharp, and as compared withnbsp;that of Lepidodendron it is strongly compressed in the median direction.nbsp;Upon it are found the usual three trace-points, the middle one of whichnbsp;corresponds, as we saw, to the transverse fracture of the vascular bundle.nbsp;We said just now, that in the outside view we can see only one of the twonbsp;pairs of facets, and now comes the somewhat difficult question whether thisnbsp;is the upper or the lower one. On this depends the determination of thenbsp;upper and lower side of the fragments of stem. If it is the lower pair, thennbsp;the scales of the armour were directed obliquely upwards and bore the scarnbsp;above on the apex, in the opposite case they were reversed and the scar isnbsp;placed on the lowest point of their margin. In the former case the development of the lower pair is the greater, in the second that of the upper,nbsp;a point which Stur has discussed at length. Now the views of authors arenbsp;much divided on this question, the scar being placed below in Sternbergnbsp;and Schimper^, above in Corda^, O. Feistmantel �'� and Geinitz'* andnbsp;recently in Renault�, while Goldenberg disposes his pieces in more thannbsp;one way and divides them accordingly into the genera Lepidophloios andnbsp;Lomatophloios, giving to the latter the species which he thinks had erectnbsp;scales and to the former those with the scales reversed. Weiss � however hasnbsp;reunited the two groups ; he insists very justly on the subjective characternbsp;of Goldenberg�s division, in which everything depends on the disposition ofnbsp;the specimens. He seeks also to lessen the value of the other marks whichnbsp;Goldenberg adduces in support of his genera. Among these may be mentioned the form of the three trace-dots on the scar, which obviously dependnbsp;too much on the preservation to be capable of being used in this manner;nbsp;and next the medullary cylinders of the Artisia kind on which Goldenbergnbsp;relies, which are said to be smooth in Lepidophloios, transversely furrowed

in Lomatophloios. Corda had previously drawn an Artisia-pith for his form; but this stem does not show the characteristic outer surface, andnbsp;might very well have belonged to a Cordaites which had been referred herenbsp;by mistake. And the remark applies also to Goldenberg, who seems tonbsp;rest in this case on Corda�s authority, and is so convinced of the correctnessnbsp;of his views, that on the strength merely of the discovery of Artisiae nearnbsp;Schwalbach (the Ottweiler beds) he thinks himself justified in assertingnbsp;that Lomatophloios occurs there h After what has now been said, andnbsp;notwithstanding all Dawson�s^ assertions, I believe that the connection ofnbsp;these medullary cylinders with the genera which we are considering isnbsp;highly questionable. In any case it is clear that we cannot turn them tonbsp;account for diagnostic purposes. Goldenberg says that the leaves in Lepi-dophloios are three-nerved, in Lomatophloios one-nerved. These leaves,nbsp;which were on several occasions found attached to their bases are linear-lanceolate ; their transverse sections, which have been figured by Corda,nbsp;show a thick keel which has been squeezed in a greatnbsp;variety of ways, and a narrow lateral wing. Thenbsp;varying effect of pressure may very easily cause thenbsp;appearance of a nervation which is different in differentnbsp;cases, so that no great importance is to be attachednbsp;to statements on this point. If it thus appears thatnbsp;there is no reason for separating the two genera, stillnbsp;there remains the question of the position of thenbsp;leaf-cushions. Weiss comes to the conclusion thatnbsp;the bases of the leaves pointed backwards, andnbsp;refers in proof of this to the branched stems whichnbsp;have been found, and which though few in numbernbsp;necessarily supply in their branches the means ofnbsp;settling the question. He has himself had the opportunity of examiningnbsp;a forked stem, but he appeals chiefly to the specimen figured bynbsp;Goldenberg�, which indeed leaves little room for further doubt. Here threenbsp;of the four rows of scars can be seen, and the two lateral rows which lie innbsp;the plane of the stratification still have the members attached to them innbsp;the form of lateral branches; the scars of the middle row have lost theirnbsp;members. The branches stand out squarrosely from the stem, but some atnbsp;least are so strongly inclined that there can be no question I'especting thenbsp;direction of the piece, and it appears that all the cushions point backwardsnbsp;towards the main stem. This figure reappears in Renault� in a distortednbsp;form, all the leaf-cushions being drawn in reversed, the stem in the uprightnbsp;position. The author is scarcely justified in saying in the explanation of

the figure: �after a figure of M. Goldenberg but put upright/ Stur too has discussed this specimen and has sought support in it for his bulbil-theory; he sees in the branches, which are all broken short off at thenbsp;margin of the plate, the bases of his brood-buds. I can myself see nothingnbsp;more in them than ordinary branches, which may perhaps have borne conesnbsp;on their extremities. The scars left by them on the stem appear from thenbsp;drawing to have been simple circles; there is no sign of the cup-formationnbsp;which is produced by the base of the sessile cone in Ulodendron. If nevertheless I incline to regard them as stalks of fructifications and not as ordinarynbsp;lateral branches, it is solely because the separation from the stem seemsnbsp;always to hav'e been basal. Supposing them however to have been vegetative branches, we should then have in this specimen a case of exceptionallynbsp;copious lateral branching. It is also in favour of the view which we havenbsp;been advocating with respect to the direction of the pieces of stem ofnbsp;Lepidophloios, that the so-called ligular pit can in almost all cases be seen innbsp;well-preserved specimens on the two facets which are visible on the mediannbsp;line; this is a point on which Stpr^ has specially insisted. This pit is distinctly shown in the figures in O. Feistmantel though he is not quite clearnbsp;in his own mind as to its meaning. Weiss ^ too has observed it and hasnbsp;figured it with his usual accuracy. The specimens of Lepidophloiae whichnbsp;have been preserved without the rind have been so little studied up to thenbsp;present time, that there is nothing definite to be said about them. Some ofnbsp;them perhaps belong to the Bergeria-forms noticed above, and which arenbsp;still imperfectly understood. A specimen given by Lesquereux ^ as Lepidophloios obcordatus, Lesq. reminds us of Knorria ; it is partly covered withnbsp;the rind of coal, but in other places shows two-lobed protuberances, whilenbsp;a small cone rises in the anterior sinus of the lobes. It may be observed innbsp;conclusion that if the question of the distinction of species is a difficult onenbsp;in Lepidodendrae, it is much more difficult in Lepidophloiae. The size ofnbsp;the leaf-cushions and the convexity of the anterior margin which bears thenbsp;scars vary greatly. In large stems the cushions may attain considerablenbsp;dimensions; in a piece before me which answers to one of Corda�s ^ figuresnbsp;I find the breadth to be sixteen millimetres. How far such differences maynbsp;be due to later growth may be left undetermined ; they are referred tonbsp;this cause by Weiss, who virtually distinguishes the species by the formnbsp;of the scar. That growth of this kind helps to produce the variations innbsp;question cannot be doubted, if we consider the colossal size of the stemsnbsp;which have these broad leaf-bases.

The genus Halonia, Ldl. and Hutt. is closely allied to Lepidophloios, and Cyclocladia, Goldenberg not Ldl. and Hutt. is not distinct from

� Stur (5), t. 19. nbsp;nbsp;nbsp;� O. Feistmantel (3), t. 33, f. i, and t. 34, f. 3.

Halonia. As Halonia is on the whole of rare occurrence, only a few authors have described it with any fulness. Carruthers�s ^ account of it isnbsp;good and perspicuous, and is accompanied with abundant examination ofnbsp;the literature. Halonia is very closely allied to Lepidophloios, so closelynbsp;that O. FeistmanteH desired to unite it at once with L. laricinus. Wherenbsp;the covering of scale-like leaf-bases on the stem is preserved, which is notnbsp;often the case, it is said by authors to be of exactly the same character asnbsp;in Lepidophloios. Figures of stems in this condition will be found in O.nbsp;Feistmantel but the execution of them leaves much to be desired ; therenbsp;are similar figures also in Schimper'^ and Lesquereux Instead of fournbsp;rows of sunken scars we have here six to eight vertical lines of prominentnbsp;bluntly rounded protuberances, which are surrounded by leaf-bases andnbsp;show a rounded often depressed scar of separation on the apex only.nbsp;Mould-specimens, in which these scars are especially distinct, are thenbsp;foundation of Goldenbei'g�s � account of Cyclocladia. Cyclocladia is sometimes found in the neighbourhood of Saarbriicken, and I have satisfiednbsp;myself of its identity with genuine Haloniae through the medium of a stemnbsp;found by myself in that locality and agreeing in every respect with thenbsp;figure. Casts without the outer rind are much more abundant. In thisnbsp;form Cyclocladia occurs not unfrequently in the Millstone Grit of thenbsp;English Coal-measures. A fine specimen has been figured by Binney'^,nbsp;and similar ones will be found in Brongniart * and in Bindley and Hutton �.nbsp;On these casts the traces of the foliar vascular bundles are seen onlynbsp;in the form of the well-known small linear protuberances; the scars ofnbsp;separation on the apex of the protuberances may have a distinctly circularnbsp;outline and be depressed, but with a central raised bundle-trace-point;nbsp;and when, as often happens, there is nothing more to be seen of the pointsnbsp;of emergence of the foliar bundles, the Haloniae have sometimes a wonderful resemblance to the Stigmariae which will have to be considered laternbsp;on. Binney^� has described pieces of stem of this kind, the connectionnbsp;of which with Haloniae might appear doubtful where their anatomicalnbsp;structure is not known. Such specimens gave rise to the view thatnbsp;Haloniae must be the roots of Lepidodendreae, a view which we find innbsp;older authors, Dawes for example, and which was subsequently maintainednbsp;by Binney in spite of the discovery of more than one specimen showingnbsp;the leaves, and by Renault also with certain limitations. The remainingnbsp;authors, Schimper^^ among them, consider that we are dealing in this casenbsp;with branches of lepidendroid growths, and that the protuberances repre-

1 Carruthers (12). nbsp;nbsp;nbsp;O. Feistmantel (3).nbsp;nbsp;nbsp;nbsp;^ O. Feistmantel (3), tt. 36, 37.nbsp;nbsp;nbsp;nbsp;* .Schimper

(1), t. 66. nbsp;nbsp;nbsp;* Lesquereux (1), vols. i, 11, t. 87, f. i. ' Goldenberg (1), t. 3, f. ii. � Binney

(1), in, t. 18. nbsp;nbsp;nbsp;* Brongniart (1), vol. ii, t. 28.nbsp;nbsp;nbsp;nbsp;� Lindley and Hntton (1), vol. iii, t. 228.

� Binney (1), III, t. 16, f. i, and t. 17, f. i. � Dawes (1). Renault, vol. ii. Schimper (1).

sent small abbreviated lateral branches, the extremities of which were probably occupied by cones of fructification and have dropped off. Whennbsp;Renault takes some of these forms for rhizomes and others for fertilenbsp;branches, the construction is artificial, and in my judgment rests on verynbsp;weak foundations and must be rejected. The anatomical reasons which henbsp;advances in support of it will have to be discussed further on when we arenbsp;giving an account of the anatomy of these plants. He imagines too thatnbsp;he has seen the root still attached to a protuberance in one of Binney�snbsp;specimens^; but this is shown to be a mistake by Williamsonwho examined the original in Owens College in Manchester and ascertained thatnbsp;the supposed root was a casual corner of the enveloping sandstone. Thenbsp;latter author moreover long before produced weighty reasons for thinkingnbsp;that Haloniae must have been the fruit-bearing branches of the crown ofnbsp;lepidendroid plants; in a lengthy note on these forms ^ he describes annbsp;ordinary and evident branch of Lepidodendron, which after bifurcationnbsp;retains its character on one branch and assumes that of Halonia on thenbsp;other. In this case therefore we can no longer speak of our fossil beingnbsp;of the nature of a root, and the idea of a rhizome is excluded, or else thenbsp;normally constituted sister-branch must also be supposed to belong to thenbsp;subterranean parts; we also obtain a point of vantage for determiningnbsp;other more imperfect specimens. This unhappily is all that can be saidnbsp;about Haloniae; we know neither their leaves nor their fructifications;nbsp;neither leaf nor fructification has yet been found in immediate connectionnbsp;with them.

The structure of the stems and branches of Lepidodendreae is well known to us from the abundant material supplied by the calcareousnbsp;nodules of the English Coal-measures. Renault has also made us acquainted with some small and important stems from Autun, but they arenbsp;extremely rare in that locality; nor is this surprising, since the entirenbsp;group sinks into comparative insignificance as early as the upper portionnbsp;of the Carboniferous formation, to which the beds at Autun belong. Onnbsp;the other hand, we should scarcely know anything of the structure of thenbsp;leaves, if we did not find them preserved in the cones of the fructification, of which we shall speak again presently. We thus are able withnbsp;some degree of confidence to infer the structure of the foliage-leavesnbsp;from the character of the fruit-bearing leaves. The structure of thenbsp;stem, with all the variety of its details, follows everywhere essentially thenbsp;same fundamental plan. We find a central bundle-strand, from the periphery of which the leaf-traces are given off and ascend in a curved line,nbsp;and a parenchymatous cortical tissue separating into layers of dissimilarnbsp;character, the outer surface of which, even in thick stems, is bounded by

' Renault (�2), vol. ii, t. 8, f. i. Williamson (5).nbsp;Williamson (1), li, p- 225.

the epidermis-covered tissue-layer which forms the leaf-cushions. Sometimes the growth in thickness of the stem falls either wholly or principally to certain portions of the cortex only, and in that case the development ofnbsp;the axile bundle is relatively small. But various forms of the group are sonbsp;far differently constituted, that they have in addition a secondary woodynbsp;body, the product of cambium, which forms a ring round the central bundlenbsp;and may in certain circumstances be of very considerable size.

These various stems thus differing in structure cannot of course be referred with perfect certainty to the species founded on the charapter ofnbsp;the surface. The preservation of the leaf-cushions in our material nevernbsp;suffices for this, and in the majority of cases even the genera cannot benbsp;distinguished. When identifications of the kind are nevertheless attempted,nbsp;they are apt to appear somewhat arbitrary in character. This is the casenbsp;for example with a type of Lepidodendron extremely abundant in thenbsp;calcareous nodules of the Lancashire coal-field, which has been referred bynbsp;Carruthers ^ to Lepidodendron selaginoides, Stbg, itself a decidedly obscurenbsp;form. Williamson^ has followed Carruthers in this, though there wasnbsp;already another name for the species, L. vasculare, Binney, whereas he hasnbsp;elsewhere cautiously applied to the types which differ in their anatomicalnbsp;structure a peculiar nomenclature which runs parallel with the other. Thenbsp;latter is in my opinion the more convenient plan, because the same structure-type may contain distinct species which we cannot distinguish from onenbsp;another.

The simplest case is presented to us in Lepidodendron rhodumnense, Ren., which was found by Grand� Eury near Combres in the Department ofnbsp;the Loire and has been described by Renault�. Young branches have thenbsp;leaves still attached to them; these leaves spread almost at a right anglenbsp;with the branch and are then curved upwards and become hooked; thenbsp;transverse section of their basal portion is transversely rhombic, that of thenbsp;upper part is flatly crescent-shaped, and they contain a single mediannbsp;vascular bundle. The central bundle-strand of the stem is homogeneousnbsp;in character and consists entirely of scalariform tracheides; its circumference shows a number of small tooth-like projections, which answer to thenbsp;transverse sections of the points of attachment of the leaf-traces. Thenbsp;section passes through the weak trace-bundles in the cortex at differentnbsp;points in their course. The entire woody bundle is surrounded by a verynbsp;thin layer of delicate elongated parenchymatous cells, which should belongnbsp;to the bast, not, as Renault thinks, to the bundle-sheath. In the xylemnbsp;the tracheides of smallest size on the transverse section lie in groups on thenbsp;periphery, and these groups correspond to the attachment of the leaf-tracesnbsp;and are explained by Renault to be protoxylem-elements. The rind

separates into three layers. The innermost, which consisted probably of spongy parenchyma, has entirely disappeared. The outer layer is a stoutnbsp;parenchyma, and contains the leaf-cushions which are cut through atnbsp;different elevations. The third layer, which is the boundary on the outernbsp;side of the cavity formed by the disappearance of the innermost layer,nbsp;consists of a few layers of right-angled cells forming regular radial rows.nbsp;Renault was also able to investigate an older bit of stem some five centimetres in thickness. Here m the middle of the solid central xylem-strand

Fig. 22. Dictyoxylon-structure of the rind, as it occurs In some Lepidodendrae and SIgillariae, and in Lyginoden-dron etc. A transverse section of the outer rind of Lepidodendron rhodumnense, B. Ren., showing the anastomosing plates of sclerenchyma which bound the me.shes filled with parenchyma ; the longitudinal .section is quite similar, onlynbsp;the sclerenchymatous elements are seen in elongated form. B impression of the inner side of such a Dictyoxylon-rindnbsp;separated from the stem. The ribs are more prominent owin^ to the disappearance of the parenchyma and answer tonbsp;the furrows. The rhombic cu-shions fill the depressions caused by this disappearance of tissue in the meshes. A afternbsp;Renault \ B after Williamson

is an irregular fissure-like gap. The character of the rind, which had lost its original outer surface, is peculiar. The parenchymatous fundamental tissuenbsp;is traversed by plates of sclerenchyma, which run on the whole in a radialnbsp;direction, but are so curved and undulated that they cut one another atnbsp;regular distances at an acute angle, and thus the parenchyma is seen on thenbsp;transverse and tangential sections to be divided into fusiform segmentsnbsp;(Fig. 22, A). Since these segments are of nearly the same length, zonesnbsp;are formed at the places where the plates cross one another, and as thenbsp;sclerenchymatous tissue predominates in the zones, the unaided eye sees onnbsp;the transverse section a system of circular band.s. This peculiar arrange-

ment of the tissue, evidently a special provision for giving firmness to the plant, will be met with again more or less strongly developed in differentnbsp;species, and especially in many Sigillariae. Cortical tissues of this kind,nbsp;separated from the woody bodies to which they belonged, are met withnbsp;not unfrequently at Autun, and received from Brongniart the provisionalnbsp;name of Dictyoxylon, which being no longer required as a generic namenbsp;may now very well be used as a short expression for this peculiar structure.nbsp;It has been already stated in the Introductory chapter on p. 7 that we alsonbsp;have the traces of Dictyoxylon-rinds in the form of impressions. It isnbsp;obvious that after the parenchyma had rotted away, impressions of the network might in certain circumstances be formed, and in that case thenbsp;mineral matter making its way into the meshes of the net would formnbsp;irregular fusiform humps separated from one another by sharp deep furrowsnbsp;corresponding to the ridges of sclerenchyma. It is to a state of preservation of this kind that Williamson^ has referred the form belonging tonbsp;Sagenaria fusiformis which has been figured by Corda^, and also an impression which was described by Gourlie as Lyginodendron Landsburghii,nbsp;and this name he has applied to a distinct collective form with a verynbsp;remarkable structure which he had previously named Dictyoxylon, andnbsp;which must be discussed further on. I have not myself seen Gourlie�snbsp;work; a specimen of the state of preservation in question, which I possessnbsp;from the Bacmeister seam in the Hannibal mine near Essen, makes menbsp;think Williamson�s interpretation very plausible.

A second very different type is presented to us in Renault�s � Lepido-dendron Jutieri. We are not in a position unfortunately to arrive at any certain decision with respect to this form, since it has not up to the presentnbsp;time been either figured or fully described. It is known only in a branchnbsp;one hundred and five millimetres in length and fifty-eight millimetres innbsp;thickness and split longitudinally, which was found near Autun. Itnbsp;appears from Renault�s brief remarks that its thick rind consists of homogeneous parenchyma ; of its axile portion this author says : � This specimennbsp;appears to me to be without the continuous wood-cylinder which is metnbsp;with in our former Lepidodendrons, and which would be represented onlynbsp;by a circle of vascular bundles giving rise to the strands which pass to thenbsp;leaves.� It is not even certain therefore whether we have before us a circlenbsp;of bundles surrounding a central pith, or a single strand with its centralnbsp;portion formed of parenchymatous tissue and giving off a number ofnbsp;vascular groups from its periphery. We will hope that this fossil will soonnbsp;be more thoroughly investigated j its importance will appear still furthernbsp;when we are considering the group of Sigillarieae.

Carr. Williamson) is very exactly known; the fullest account of it will be found in Williamson^. Binney�s^ fine figures of this form should alsonbsp;be consulted ; the text which they accompany is not it is true of equalnbsp;value, and should be read with great circumspection. If we look first atnbsp;the primary structure, we find in the centre of the stem a woody cylindernbsp;slightly developed in proportion to the thickness of the rind, circular onnbsp;the transverse section, and composed of scalariform and reticulately-thick-ened tracheides, between which parenchymatous cells in tolerably largenbsp;quantity and increasing in number towards the centre are interspersednbsp;singly or in groups. The longitudinal section shows that the tracheides arenbsp;of two kinds, that sometimes they are elongated and tubular, and again shortnbsp;and isodiametric, and with their cross walls usually showing particularlynbsp;beautiful reticulate markings. The latter kind is found chiefly in the middlenbsp;of the bundle, the former is present everywhere and is the sole constituentnbsp;of the periphery. The narrowest elements of the bundle are found on itsnbsp;outermost margin. The rather broad ring of bast which surrounds thenbsp;wood-cylinder has generally disappeared up to its innermost layer; it is butnbsp;rarely that its delicate tissue is perfectly preserved. It is traversed by thenbsp;xylem-strands of the leaf-traces, the transverse sections of which are found innbsp;great numbers in the immediate neighbourhood of the edges of the xylemnbsp;of the central strand, and are surrounded by the remains of bast-tissue.nbsp;In the well-preserved preparations before me I see only one homogeneousnbsp;bundle of tracheal elements on the transverse section of the leaf-trace.nbsp;The protoxylem-groups I am unable to distinguish with the needful certainty; there ought to be two of them present as in Ferns, according tonbsp;Renaultwho however relies for this point on Corda�s* extremely doubtfulnbsp;figures. How much uncertainty still remains with respect to these points isnbsp;further shown by van Tieghem�s� account, who ascribes a collateral structurenbsp;to the leaf-traces of Lepidodendron and finds their initial strand on thenbsp;outer borders of the xylem. He then makes the homogeneous centralnbsp;cylinder of the stem be formed by the union of several such bundles withnbsp;their xylem-portions. The state of preservation of the associated bast-portion being so unfavourable, I do not venture to decide whether we havenbsp;a concentric bundle before us or a collateral, although for various reasons,nbsp;to which I shall presently have to return, I incline to the view that the plannbsp;of structure is of the latter kind. Moreover this collateral structure occursnbsp;at the present day, according to Russowand Janczewski, in Isoetes. Andnbsp;here we may draw attention to a point which will have to be noticed oftennbsp;again, namely how little we can rely on distinguishing the protoxylem-

' Williamson (1), n, in, xi. nbsp;nbsp;nbsp;^ Binney (1), ni, 2 and 3.nbsp;nbsp;nbsp;nbsp;* Renault (2), vol. iii, Introd.

p. H ; t. 10. nbsp;nbsp;nbsp;� Corda (1), (Lomatophloios crassicaulis, t. 3, f. 8).nbsp;nbsp;nbsp;nbsp;� van Tieghem (2),

strands when we only know the mature state of the bundles, and how dangerous it therefore appears to draw conclusions in this direction fromnbsp;the relative size of the elements, as has often been done by Renault, thoughnbsp;at other times he lays great stress and rightly on this point. On the outernbsp;limit of the bast-portion is a sheath of stout parenchyma, which, consistingnbsp;only of a few cell-layers, is often preserved in cases where both the bastnbsp;and the inner layer of the cortical tissue lying outside the bast are entirelynbsp;destroyed.

The rind is in general very thick, and separates into three cylinders one within the other, which may conveniently be distinguished in thenbsp;following remarks as the outer, middle, and inner cylinders. The innernbsp;cylinder, which is evidently composed of loo.se spongy tissue, is almo-stnbsp;always entirely destroyed ; a broad circular space filled with crystallinenbsp;carbonates and detritus which has floated into it takes its place (Fig. 23).nbsp;Remains of this tissue have been preserved in a few specimens, for examplenbsp;in a transverse section figured by WilliamsonThe outer cylinder readilynbsp;comes away from the middle one with a sharp circular line of separationnbsp;and is therefore often wanting, and may occur detached and variouslynbsp;curved and rolled up. Its outer margin formed by the epidermis is renderednbsp;uneven by crowded protuberances, the transverse sections of the leaf-cushions, and these sections necessarily vary much in size and form sincenbsp;they cut the cushions at different elevations. This outer cylinder is composed of stout-celled parenchyma, the cells of which beneath the epidermisnbsp;add continually to the thickness of their walls, and assume the character ofnbsp;sclerenchyma. The epidermis itself is often removed, and then the surfacenbsp;bears some resemblance to a Bergeria-cast. Lastly, if the whole of thenbsp;outer cylinder is wanting, we then have the stems in the well-known state innbsp;which they so frequently occur, covered with small flat protuberances, in thenbsp;usual phrase, stripped of their rind. The middle cylinder, at least as thicknbsp;as the outer and inner cylinder put together and usually much thicker,nbsp;is traversed on the transverse section by radiate stripe-like lacunae (Fig. 23).nbsp;In each of the lacunae runs, longitudinally or a little obliquely, the uppernbsp;horizontal portion of the emerging foliar bundle, of which the xylem-portionnbsp;only is usually preserved. The entire tissue-mass of this cylinder is parenchymatous, but two essentially different layers may always be distinguishednbsp;in it, the relative thickness of which changes with time; in young stemsnbsp;with a small transverse section the inner layer is the thicker and the outernbsp;is often only a very narrow zone, while in older pieces of stem it is the outernbsp;zone which attains to very considerable thickness. In this zone the somewhat thin-walled parenchyma-cells are rectangular on the transversenbsp;section and arranged in radial rows, on the other they have a much broader

lumen, are thick-walled, roundish in shape, and irregular in their disposition. From the arrangement of the cells in the outer layer, and still more from the circumstance that having been at first feebly developed theynbsp;increase so much in size in old specimens and surpass the inner unalterednbsp;cells, we may conclude that the outer layer is formed by the constantnbsp;activity of a meristem. We may in fact satisfy ourselves from specimens

in a particularly good state of preservation, that near the outer edge of the layer there is such a hollow cylinder of meristematic compressed cells,nbsp;which may be compared to some extent with the phellogen of the rind innbsp;recent plants; this zone gives rise to a considerable amount of phellodermnbsp;on its inside, while the phellem is produced in small quantities only, andnbsp;Usually comes away with the outer cylinder in the form of a thin layer

of radially disposed cells. As this phelloderm consists of prismatically elongated cells, it is ternied by Williamson the � outer or prosenchymatousnbsp;layer of the bark,� the primary tissue being with him � the middle parenchymatous part of the bark.� When Renault regularly calls this phelloderm-portion of the middle cylinder the �assise sub�reuse,� he means to callnbsp;attention to its connection with the peridermal system. For we cannotnbsp;imagine any formation of real cork either in the phelloderm or in thenbsp;phellem ; the main growth in thickness of the tree devolves on the phellogen,nbsp;and if this were to produce anything but normal parenchyma-cells on thenbsp;phellem-side, the tissue-cushions of the leaf-bases would at once die awaynbsp;and disappear, but this is by no means the case. On the contrary, we findnbsp;them still preserved on stems in which the periderm has already reachednbsp;a considerable development'.

It was said above that the type of Lepidodendron vasculare, Binn. is further distinguished by the appearance of a secondary woody body.nbsp;Lepidodendron-stems of this kind have often been described under othernbsp;names ; such are Anabathra pulcherrima^ and Diploxylon cycadoideum�,nbsp;which are one and the same form, as Brongniart'' was the first to perceive.nbsp;He and Renault do not admit that they belong to Lepidodendron, andnbsp;usually speak of them by Corda�s names. Stems of this kind are termednbsp;in Binney Sigillaria vascularis, and are figured in great numbers in thenbsp;publications just cited. The secondary growth of wood begins to developenbsp;on the boundary between wood-strand and bast-portion; its inner sidenbsp;is in contact with the former and the emerging leaf-trace-bundles arenbsp;inclosed in it; the bast and the formative cambium are more and morenbsp;thrust towards the outside. In many cases the new growth does not appearnbsp;simultaneously on the whole of the circumference (Fig. 23), but is developednbsp;in a one-sided manner, and may be of great size on one side, while it hasnbsp;not even begun to be formed in the opposite quarter. It consists ofnbsp;elongated scalariform tracheides, which normally are disposed in radialnbsp;rows and increase in breadth towards the outside. It is traversed bynbsp;numerous parenchymatous medullary rays, which are seen on the tangentialnbsp;section to be of two kinds; one narrow and formed of one cell-layer,nbsp;shallow and one to a few cells in depth, and this kind is very abundant;nbsp;the other formed of several layers, but like the first of small depth, fusiformnbsp;and inclosing the emerging foliar bundles at the broadest part. As againstnbsp;Carruthers�s � views it may be observed that all these medullary rays agreenbsp;perfectly w'ith those of the roots of recent trees. The size attained by thenbsp;secondary wood here described varies much. This variation may be partlynbsp;due to specific differences, and is usually confined within moderate limits.

though Binney^ has figured a transverse section of a stem of the vasculare-type, in which the central strand, seven millimetres in thickness, is quite insignificant as compared with the secondary wood, which is sixty-twonbsp;millimetres thick. The disposition also of the tissue of the primary woodnbsp;in this specimen is somewhat abnormal.

These stems with secondary wood have hitherto been unhesitatingly regarded as more advanced states of development of Lepidodendron. Itnbsp;is necessary however to show some reasons for this view, since we knownbsp;that no such secondary formations occur in recent Archegoniatae, or only innbsp;a quite rudimentary form in Isoetes. Secondary wood is said by recentnbsp;authors to be found in older stems of Botrychium, but the point requires tonbsp;be cleared up by further investigation. The view which Renault hasnbsp;developed in conjunction with Brongniart, that the presence of secondarynbsp;xylem must exclude any form from the class of Archegoniatae, is at oncenbsp;refuted by the case of Isoetes. For if it can be shown that the character isnbsp;present in the class in one instance only and in ever so rudimentarynbsp;a form, it is difficult to see why it should not have occurred fully developednbsp;in other extinct representatives of the class. And when we see this additional character present in so many specimens, which perfectly agree withnbsp;Lepidodendron in all points of structure and surface-features, it seems to menbsp;that we shall be doing violence to nature if we ai'e determined to keep themnbsp;separate from that genus, and place them in another group of the vegetable kingdom for the sake of some view once adopted which has becomenbsp;a favourite with us. Now this is Renault�s position, when he refers thenbsp;remains in question to Sigillarieae and with them to Gymnosperms, andnbsp;Williamson ^ is quite right in maintaining that his classification rests entirelynbsp;on a petitio principii; nor can I help acknowledging that I am of his opinionnbsp;after repeated careful study of the numerous specimens in his own possessionnbsp;and in that of Carruthers, Cash, and myself. Renault has naturally endeavoured to support the view which he received from Brongniart by asnbsp;many further arguments as he could command, and their unsatisfactorynbsp;character has been also exposed at length by Williamson and Hartog�.nbsp;Renault�s prime contention is, that the surface of the specimens examinednbsp;by the English authors is not well enough preserved to allow of their beingnbsp;certainly determined to be Lepidodendron, and separated from Sigillarianbsp;on grounds which carry conviction. The characters of the latter typenbsp;will be described in the chapter devoted to it, but it has already beennbsp;remarked that great caution is necessary in distinguishing between thenbsp;impressions of certain Lepidodendrae and Sigillariae, because they affordnbsp;no absolute marks of distinction, with the exception perhaps of the dimensions of the scar of separation of the leaf. This cannot be better seen than

from the comparison of the two types by Renault^ liimself. It might indeed be supposed from this comparison that there were importantnbsp;differences in connection with the vascular bundle-trace; but it has beennbsp;already pointed out, that in Lepidodendron also, exactly as in Sigillaria,nbsp;the lateral points are most probably not to be taken as belonging tonbsp;the bundle-trace. From Renault�s objections on this point we shouldnbsp;expect that the surface of the specimens, the structure of which correspondsnbsp;to that of the vasculare-type, would bear on it the characteristic marksnbsp;of Lepidophloiae, since these are the forms in the series of Lepidodendreaenbsp;which are more like Sigillaria. But exactly the contrary is the case. Wenbsp;find elongated rhombic cushions with the bundle-trace in the normalnbsp;position, though they do not show the scar of separation, because thenbsp;epidermis has disappeared in every case which has been observed. I myselfnbsp;possess several specimens of the kind ; others have been figured by Binney^nbsp;and these are all the more instructive because, having exactly the samenbsp;surface, they are distinguished anatomically only by the presence or absencenbsp;of the secondary growth, and were accordingly named Lepidodendronnbsp;vasculare and Sigillaria vascularis. In this case the surface shows not thenbsp;least trace of any resemblance to Sigillaria. There is yet another distinctionnbsp;which Renault establishes between the two families, and which rests on thenbsp;structure of the leaf-trace-bundle; but this too will have to be noticednbsp;again in discussing Sigillariae, and we shall therefore only say what isnbsp;absolutely necessary about it in this place. Renault states that in Sigillariae the bundle is diploxylous, that is, is constructed after the manner ofnbsp;the leaf-traces of Cycadene, while in the type before us it is monoxylous.nbsp;Upon this it is to be observed that in this respect there is not the slightestnbsp;difference between the stems of Lepidodendron vasculare with and withoutnbsp;growth in thickness, and of this I have fully satisfied myself from numerousnbsp;preparations, both transverse and tangential sections. Whether they arenbsp;diploxylous or not cannot be certainly ascertained until we know whethernbsp;they belong to the collateral or the concentric type. Nothing at all can benbsp;gathered on this point from Renault�s � figure of his Diploxylon (Anabathranbsp;pulcherrima, Withain). It appears then that Williamson^ is again right innbsp;maintaining that Binney�s and Renault�s Sigillaria vascularis in the youngnbsp;state, before the formation of secondary xylem, would not be distinguishablenbsp;from a Lepidodendron vasculare. And since we found that the surface ofnbsp;the two forms was the same, and there is therefore an absence of allnbsp;differential characters, they form together one and the same species. Itnbsp;may be remarked in conclusion that Renault�s objections in this matternbsp;are the less cogent, because he can have examined little more of the

English material than two preparations of Witham�s Anabathra in a very bad state of preparation, since he writes as follows ^: � The fact observednbsp;by Williamson of young branches of Sigillaria vascularis, without exteriornbsp;centrifugal wood, forming a continuous zone round the centripetal cylindernbsp;is certainly correct, but we do not doubt that the foliar bundles given offnbsp;from it are formed, like those of Diploxylon and of the Sigillariae, of twonbsp;distinct portions with their growth inverse in relation to one another.�

The above arguments have only gained in strength from Zeiller�s� discovery, which has proved that an archegoniate fructification resemblingnbsp;Lepidostrobus is beyond doubt a Sigillaria, on which subject some furthernbsp;remarks will appear below. For now that we know that the Sigillariaenbsp;also belong to this class, the argumentation of Renault and his predecessorsnbsp;has entirely lost its point of departure. I cannot be wrong in this persuasion, when he himself has recentlynbsp;attempted to save his case by thenbsp;following assumption. Hesays�; �Thenbsp;Sigillariae, an essentially transitionalnbsp;group, would thus be divided intonbsp;Leiodermarieae or phanerogamousnbsp;Sigillariae with smooth rind allied tonbsp;Cycadeae and Rhytidolepis or crypto-gamous Sigillariae with fluted rindnbsp;near to Iso�tes.�

The behaviour of the central strand in the bifurcation of the stemnbsp;as represented by Williamson* andnbsp;Binney� is peculiar (Fig. 24). It apparently divides at that point into twonbsp;halves. The peripheral exclusivelynbsp;tracheal portion separates into two semicircular segments, and each segmentnbsp;incloses a half of the middle mixed tissue which is in immediate connectionnbsp;with the surrounding parenchyma on the side towards the centre of thenbsp;stem. Then each of the semicircular tracheal outer portions, graduallynbsp;closing in each branch round the central tissue, unites into a circle andnbsp;the normal structure is restored. Corda�s � Leptoxylon geminum mustnbsp;quite certainly be considered to be such a Lepidodendron-stem in the actnbsp;of bifurcation, though owing to its unfavourable state of preservation itnbsp;is not clear whether it belongs to this type or to that of Lepidodendronnbsp;Harcourtii, With, which we are about to consider.

' Renault (2), vol. i, p. 150. nbsp;nbsp;nbsp;�� Zeiller (12).nbsp;nbsp;nbsp;nbsp;� Renault (9).

t- 49, f. 8. nbsp;nbsp;nbsp;� Binney (1), ni, t. 14, ff, 4, 5.nbsp;nbsp;nbsp;nbsp;� Corda (1), t. 15.

distinguish species with any certainty, that of Lepidodendron Harcourtii, With, is represented by two well-defined species. One of these appears tonbsp;be very rare, and to it belongs the stem first discovered by Witham. It isnbsp;only quite recently that we have succeeded in obtaining further specimensnbsp;of it, and I am indebted to Mr. Cash�s kindness for a transverse section ofnbsp;one of these. The other species, which is tolerably plentiful in Lancashire,nbsp;was in the meantime examined repeatedly by Williamson and Binney, but itnbsp;was not distinguished from the first species and went by the same name.nbsp;We will call it here Lepidodendron Williamsoni (L. Harcourtii, Will,nbsp;ex pte, not With.). The preponderating development of the parenchymatous cortex is much more striking in the Harcourtii-type than in that ofnbsp;L. vasculare; as compared with it the central strand is still more insignificant. There is usually no secondary growth in thickness, or else it appearsnbsp;in a feebly developed and rudimentary form, and on one side only of thenbsp;periphery of the central xylem-strand. The latter separates into a centralnbsp;pith-like purely parenchymatous cylinder entirely without tracheides, and thisnbsp;is surrounded by a closed ring of tracheal elements which is sharply definednbsp;on its inner side, while its outer boundary is rendered sinuous in a peculiarnbsp;manner by the presence of numerous small sharp teeth, which correspondnbsp;to the sections of the points of attachment of the strongly decurrent leaf-traces. The transverse sections of these bundles, which have already setnbsp;out from the central cylinder, and which agree in all important points ofnbsp;structure with the trace-bundles of the vasculare-type, lie in the sinusesnbsp;and are inclosed in delicate tissue. There is this difference between the twonbsp;species, that the small teeth in the boundary-line of the central strand projectnbsp;much more sharply and are also longer in Lepidodendron Harcourtii than innbsp;L. Williamsoni. A further difference is that the trace-bundles of the formernbsp;species contain a group of bast-fibres which is wanting in those of thenbsp;latter. Hence in the one case the bundles in their course through thenbsp;rind appear under the lens to be made up of two brown points, in thenbsp;other to be single. The inner one of these two points consists of well-preserved tracheides, the outer is less distinct, and it is only in rare casesnbsp;that its cells can be certainly distinguished Between the two there isnbsp;always a gap, which was formerly filled with soft bast. Whether this ba.stnbsp;surrounded the wood-portion, in other words whether the bundle was concentric or collateral, must again be left undecided; from the figure givennbsp;by Binney^ we might almost suspect that it was collateral. But I havenbsp;not met with so well-preserved a bundle in the preparations which I havenbsp;examined.

Of the rind, it is to be observed that its outer cylinder with the leaf-cushions has never been found with the structure preserved ; for even

Witham�s original specimen figured in Lindley and Hutton and in Brong-niart ^ is merely the ordinary cast without the rind. The specimen with a Bergeria-surface figured in Binney� as Lepidodendron Harcourtii is structureless up to the central strand, which is in the act of dividing, and is fillednbsp;with clay-irOnstone; it cannot therefore be taken into consideration here,nbsp;though from the structure of the xylem-strands it is probable, if not quitenbsp;certain, that it has been correctly determined. We know therefore onlynbsp;the middle and inner cylinders, which are both of great thickness andnbsp;consist entirely of parenchyma. The growth in thickness appears in thisnbsp;case to be much less localised ; notwithstanding the great thickness of thenbsp;rind, the periderm is much less developed and not nearly so conspicuousnbsp;as in the previous type. But while in Lepidodendron Williamsoni thesenbsp;two cylinders, which differ little in the character of their tissue, are bothnbsp;as a rule in a like state of preservation and are not distinctly separate fromnbsp;one another, in the other species on the contrary the inner cylinder is morenbsp;or less destroyed�in my specimen entirely destroyed up to the leaf-trace-bundles by which it is traversed, while the outer, consisting of thick-wallednbsp;parenchyma, is remarkably well preserved. The consequence is that thenbsp;two species can be distinguished at first sight in a preparation. Thenbsp;behaviour also of the central bundle in the formation of lateral branches isnbsp;known in the case of the type of Lepidodendron Harcourtii, and has beennbsp;figured by Williamson The strand divides exactly as in the formationnbsp;of a dichotomy, only the two parts are not of equal size, as they are in thenbsp;latter case, which has been observed in Lepidodendron vasculare. A smallnbsp;segment in the form of a portion of a flat arch separates from the circularnbsp;tracheid-zone of the bundle, so that the remaining portion is seen to havenbsp;an aperture on one side and to be in the form of a horse-shoe. The smallnbsp;opening thus formed soon closes again above, and thus forms a longishnbsp;lateral slit in the tracheal tube, through which the central parenchyma ofnbsp;the strand enters into communication with the rind. The process wasnbsp;observed to be exactly the same in the normal bifurcation of the vasculare-type, only there the opening was at the top of the basal piece in the anglenbsp;of the dichotomy. The two cases are accordingly distinguished only bynbsp;the lateral displacement connected with the formation of a sympodium.

Various previously described remains with imperfectly preserved inner structure appear from the statements of authors to belong to the type ofnbsp;Lepidodendron Harcourtii. Lepidodendron nothum and L. Richteri �nbsp;from the Cypridinae-schists (Upper Devonian beds) of Saalfeld may benbsp;first mentioned, and after them L. squamosum � from the Carboniferousnbsp;Limestone of Glatzisch-Falkenberg, in which the form of the central

^ Lindley and Hutton (1), vol. ii, t. 98. nbsp;nbsp;nbsp;� Brongniart (7), t. 30,nbsp;nbsp;nbsp;nbsp;� Binney (1), m, t. 14, f. i.

* Williamson (1), XI, t. 52. nbsp;nbsp;nbsp;^ Unger (5), tt. 10, 11.nbsp;nbsp;nbsp;nbsp;^ Goppert (12), tt. 21, 22.

strand is well preserved, and the tracheides with their structure can be distinguished. The plant too described by Corda^ as Lomatophloiosnbsp;crassicaulis certainly belongs to this place ; all the characters which marknbsp;the xylem-strand in this type are given in one of his figures^ withnbsp;unmistakable distinctness. I have made assurance doubly sure bynbsp;examination of an original preparation of Corda in the botanical department of the British Museum which was sent by him to R. Brown. Itnbsp;shows only the very small central cylinder preserved in transparent stone,nbsp;the cell-walls of which have one and all been changed into opaque blacknbsp;coal. The well-preserved teeth of the periphery projecting sharp and longnbsp;show distinctly that it belongs to the true Lepidodendron Harcourtii, andnbsp;not to L. Williarnsoni. Since Corda found the outer surface in thesenbsp;remains well preserved, there can be no doubt that Lepidophloios had thenbsp;structure of Lepidodendron Harcourtii. Whether this was the case withnbsp;all the species, and whether it was not also the case with true Lepidoden-drae, remains an open question and is not prejudiced by Corda�s discovery.

Young terminal ramifications of Lepidodendrae have been found here and there, though not frequently, in the Lancashire and Yorkshire coal-field.nbsp;On the other hand they are found in great quantities in the plant-petrifactionsnbsp;of Burntisland � and Laggan Bay in ArranScotland, which were noticed innbsp;the introductory chapter ; they are accompanied in both localities by largernbsp;stems and branches, in which a strong secondary growth of wood has beennbsp;developed. Many fructifications also occur with these remains in Burntisland showing the same characteristic features, and it is natui-al to assumenbsp;with Williamson that the remains of the different parts of the same speciesnbsp;lie side by .side in these deposits, though absolute proof of this cannot atnbsp;present be produced. To the fragments from Burntisland thus united tonbsp;one another Williamson has given the name Lepidophloios brevifolius, butnbsp;he has abstained from naming the Arran plants. If the stronger stems arenbsp;compared with the two preceding types, it appears that the Arran Lepidodendron is nearer the type of Lepidodendron Harcourtii, and that thenbsp;Burntisland forms may occupy an intermediate position between that typenbsp;and the type of L. vasculare. Its central strand is differentiated as in L.nbsp;Harcourtii, but it has not the peculiar angular outline, and the trace-bundlesnbsp;seem, as in L. vasculare, to be only slightly carinately decurrent. It agreesnbsp;also with L. vasculare in the strong development of the secondary wood,nbsp;and this distinguishes it at the same time from a stem of true L. Harcourtii.nbsp;Unfortunately we know next to nothing of the characteristic features of thenbsp;surface in either forni. In both cases the young branches show essentiallynbsp;the same structure, only they are most strongly compressed in the remainsnbsp;from Burntisland. The outer cylinder of the rind is preserved, and is

furnished with prominent angular projections of varied shape, the transverse sections of the leaf-cushions, and each projection receives a vascular bundle.nbsp;Dichotomies, such as have been described above, are frequent. In the preparations before me I find the epidermis preserved, but in many casesnbsp;already partly separated by a fissure caused possibly by maceration. Thenbsp;central bundle must be discussed at somewhat greater length. In allnbsp;the transverse sections of branches from Burntisland which Williamson wasnbsp;able to examine, the centre was formed of parenchymatous tissue, thenbsp;periphery of a closed ring of tracheides which showed on the inside a slightlynbsp;irregular boundary-line. In the smallest branches the mass of centralnbsp;parenchyma was small, and was surrounded only by two or by a few layersnbsp;of tracheides. In larger branches it was broader, the ring of tracheidesnbsp;thicker, and consisting in the radial direction of from five to eight elements.nbsp;Lastly, still thicker branches showed the presence of secondary wood, andnbsp;the larger the transverse section of a stem or branch, the more voluminousnbsp;was the mass of parenchyma of the central strand and the broader the layernbsp;of tracheides surrounding it. The same results were obtained from thenbsp;examination of the Arran material. Here in the very smallest branchesnbsp;there was no parenchymatous centre at all, the entire central strand wasnbsp;composed of one form of tracheides ; the medullary tube made its appearance as the branches grew larger. I have before me a young branch of thisnbsp;kind from Halifax for which I am indebted to Mr. Cash; its structure agreesnbsp;perfectly with that of a specimen figured by Williamson and shows anbsp;closed tracheal strand. If then all the remains from Burntisland or Arrannbsp;are brought together to form one vegetable species, as is done by Williamson, and if further the whole of the known branches and stems are combinednbsp;in sequence of time to make up a course of development which each of themnbsp;would have passed through if undisturbed in its vegetation, we are driven innbsp;presence of the actual conditions to the conclusion that the central strandnbsp;possessed unlimited growth, which is manifested in the enlargement of thenbsp;inner parenchyma, and in the growth of the outer layer of tracheides, both in thenbsp;surface direction by intercalation and in thickness by increasing the numbernbsp;of the elements in the radial direction. And therefore Williamson also hasnbsp;concluded, and quite logically from his position, that in the Arran Lepido-dendron, for example, the central strand at first solid begins by formingnbsp;parenchyma in its centre and then goes on increasing by growth, and thatnbsp;this growth and the constant increase in volume which results from it is innbsp;no way retarded or stopped even by the development of secondary tissue. Itnbsp;is this latter point, as Renault '^ justly urges, which is not very intelligible,nbsp;since it is difficult to see how the secondary wood can allow space for thenbsp;further growth of the primary strand; and we know that this growth in

living plants, as in the stems of Tecoma radicans, inevitably results in the bursting of the outer ring of wood, no signs of which have ever beennbsp;observed in Lepidodendron. We must indeed have recourse to assumptionsnbsp;before the formation of secondary wood, in order to understand the increasenbsp;in size of the central strand, as Williamson conceives it. First of all, if hisnbsp;view is correct, there must always have been parenchyma-cells presentnbsp;between the tracheides, to be the starting-point of the formation of the innernbsp;parenchyma in the originally solid strand. Next, these parenchyma-cellsnbsp;must have been able subsequently to give rise to more tracheides, for thenbsp;increase in the thickness of the peripheral ring could not otherwise benbsp;explained ; and lastly, cells of the kind must have been introduced into thenbsp;ring itself, to I'ender its surface-growth possible. All this is however quitenbsp;possible ; the single parenchyma-cells from which the development proceeds,nbsp;may easily have been overlooked in the preparations, and it is indeed innbsp;favour of this supposition, that Williamson^ has in a few cases met with thenbsp;central parenchyma apparently in the state of meristem. The preparationnbsp;here cited, which his kindness enabled me to examine, certainly gives quitenbsp;this impression. If therefore we allow the possibility of the increase innbsp;volume up to the time when the central strand is inclosed in the secondarynbsp;wood, it is entirely excluded after that time, as has been already said.nbsp;And this shows that the way in which Williamson has arranged his preparations to represent a course of development cannot be right. It is to benbsp;remembered, that we must not simply compare the terminal ramifications ofnbsp;the head of a tree with the still young and growing ends of the main shootnbsp;or of its subordinate branches. The central strand in the main shoot andnbsp;in the branches may and will have had a very different diameter at thenbsp;beginning of the growth in thickness from that of the later generations ofnbsp;branches, the last of which may have had no growth of the kind. If this isnbsp;so, and I have no doubt whatever about it, every arrangement of the singlenbsp;stages into a successive series is naturally precluded, for we must know tonbsp;what part of the branch-system each piece belonged, and this in the fragmentary condition of our remains we are unable to determine.

The chief sources of our knowledge of the anatomy of Halonia are the works of Dawes Binney� and WilliamsonFrom these we learn thatnbsp;there is on the whole essential agreement in structure between this form andnbsp;the type of Lepidodendron Harcourtii, or with that of the Burntislandnbsp;plant; there is indeed no growth in thickness, but it is quite intelligible thatnbsp;there should be no such growth in a branch serving only as a fructification-stalk. Only we know nothing of the character of the outer cylinder of thenbsp;rind, since this has never been observed in the specimens with the structure

� Williamson (1), XII, t. 33, f. 20. nbsp;nbsp;nbsp;* Dawes (1).nbsp;nbsp;nbsp;nbsp;^ Binney (1), iii.

preserved. Binney ^ has figured fine transverse sections of his Haloniae, but unfortunately they are not sufficiently magnified to show the behaviour ofnbsp;the different traces which traverse the rind, and which run partly to thenbsp;leaves, partly to the scars where the lateral branches have separated fromnbsp;the stem; for the two are according to Williamson essentially different.nbsp;The foliar bundles arise normally on the outside of the wood-cylinder, butnbsp;without affecting its structure. The other and much stronger bundlesnbsp;behave exactly like those which supply lateral branches in Lepidodendronnbsp;Harcourtii in the manner described above; they originate in a division ofnbsp;the central strand, in which a fissure-like gap appears above the point ofnbsp;departure. I have seen the preparations in Williamson�s collection, but theynbsp;have unfortunately never been figured. If the section does not happen tonbsp;hit on one of the very small fissures, as is often the case, then the centralnbsp;strand is not distinguishable from the normal type of Harcourtii; thisnbsp;perhaps is the explanation of the absence of this peculiar character fromnbsp;Binney�s drawings. It was mentioned above that Renault^, combiningnbsp;Dawes� and Binney�s views in modified form with those of other authors,nbsp;pleads for the division of Haloniae, some of which he looks upon as rhizomes, the others as aerial branches of Lepidodendreae. To make thenbsp;origin of this opinion intelligible it should be first observed, that thenbsp;majority of palaeophytologists regard the Stigmariae, which will have to benbsp;considered further on, as the rooting organs both of Sigillariae and Lepidodendreae. But since these Stigmariae contain undeniable secondary wood,nbsp;and Renault, following Brongniart�s views, cannot allow of any such formation in Archegoniatae, he is obliged to keep all Stigmariae for the Sigil-larieae, and is then met by the diificulty, that there are no subterraneannbsp;organs left for the Lepidodendreae. He inclines therefoi'e to see theirnbsp;rhizomes in Haloniae. And since this does not do for all their forms fornbsp;reasons which have been already noticed, he endeavours by help of thenbsp;difference which exists between Williamson�s and Binney�s descriptions tonbsp;separate them into two groups, and considers the specimens of the latternbsp;author, who finds no difference in the bundles of the trace, to be rhizomes,nbsp;and those of Williamson with two kinds of traces, one of which originatesnbsp;in the division of the axile strand, to be branches of the heads of the treesnbsp;to which they belong. That this is the true account of the process ofnbsp;thought in Renault�s mind, as it may be gathered from his various publications, is sufficiently attested by the following passage^: � The separation ofnbsp;the species of Halonia into two distinct groups, which we have noticed herenbsp;as a hypothesis serving to reconcile the anatomical results of different Englishnbsp;authors, is justified also by the examination of the figure given by Brongniart,�nbsp;amp;c. The figures cited appear to me to be merely casts of various states of

Binney (1), in, tt. 16, 17. ^ Renault (2),nbsp;3 Renault (2); vol. iu, Introd, p. 22,

decortication. But apart from this, I cannot think it allowable to bring contradictory statements of this kind into agreement with one another bynbsp;means of conciliatory hypotheses without fresh investigation. It is mynbsp;opinion that we ought not at present to hold either to Binney only or onlynbsp;to Williamson ; the older publication by Dawes, which was excellent in itsnbsp;time, cannot now be taken into consideration. I have myself no doubt asnbsp;to which of the two first authors deserves the greater confidence. Binneynbsp;is dead, and his original specimens have been for a long time inaccessible:nbsp;whenever the opportunity comes for submitting them to fresh examination,nbsp;it will be possible finally to settle this question ; and then his Haloniae alsonbsp;will ultimately show the two kinds of trace-bundles, which, as he says himself in the Introduction, may not have been brought out with the necessarynbsp;distinctness by the entirely unprejudiced draughtsmen. A few words mustnbsp;be added in conclusion about Ulodendron. Carruthers^ and Williamson^nbsp;have stated a few facts only respecting its inner structure, which is said tonbsp;be essentially that of Lepidodendron Harcourtii. But I confess that I amnbsp;not perfectly satisfied with regard to the determination of Williamson�snbsp;specimens, for he encountered on the tangential section � transverselynbsp;rhombic leaf-cushions, such as occur in Lepidophloios but not in Ulodendron ; and leaf-bases are figured in the radial section *, which also remindnbsp;us rather of Lepidophloios. It is true that the great cone-scars are said tonbsp;be in the usual two-rowed position in the specimen; unfortunately no figurenbsp;of the surface is given.

The fructifications only remain to be considered. These have long been known as cone-like extremities of shoots close set with spirallynbsp;arranged sporangiferous leaves, the connection of which with indubitablenbsp;branches of Lepidodendron has been so clearly established in particularnbsp;cases, that the true nature even of such specimens as have not been metnbsp;with in the same close connection cannot usually be disputed. Still figuresnbsp;proving this are not common in the literature ; those of Stur�, Lesquereux�nbsp;and Brongniart� may be named as the most important. Further confirmation is obtained from the results of the anatomical investigation of the axesnbsp;of petrified specimens, which show the essential points of the structure ofnbsp;the shoots of Lepidodendron. These cones, usually known by the collectivenbsp;name of Lepidostrobus, are everywhere abundant on heaps of refuse coal innbsp;the form of impressions; they occur here and there as petrifactions in thenbsp;English calcareous nodules, and in certain sphaerosiderites from the neighbourhood of Wolverhampton. Few silicified specimens are known, but innbsp;these the inner structure is wonderfully well preserved.

f. 28. nbsp;nbsp;nbsp;* Williamson (1), II, t. 28, f. 27.nbsp;nbsp;nbsp;nbsp;� Stur (5), t. 19, f. 9.

t. 107, f. 2. nbsp;nbsp;nbsp;� Brongniart (1), vol. ii, t. 24, f. 5 and t. 25, f. 2.

The study of the impressions has revealed the main features in the organisation of these cones. The straight usually tolerably thick axis,nbsp;which is bifurcated in one instance only \ bears all round it sporophyllsnbsp;closely crowded and exactly like one another, on each of which can benbsp;distinguished the peculiarly developed leaf-base (the cushion of the vegetative homologue), the single sporangium attached to it, and the lamina.nbsp;The leaf-base, the characteristic features of which are correctly describednbsp;by Stur is developed in the form of a long pyramid scarcely narrowingnbsp;upwards and sometimes winged on the sides, which stands out at a rightnbsp;angle from the axis; its cross section is transversely rhombic and flattenednbsp;in the median direction ; it bears on its upper side the cylindrical usuallynbsp;very capacious sporangium, which is bluntly rounded at the extremity, and

sometimes even allows the spores to be seen in it. Binney�s � figures should be consulted. The usually lanceolate lamina is attached by its entire breadthnbsp;to the top of the leaf-base, and bends upwards so as to be parallel to thenbsp;axis, and to overlap and cover the laminae next above it like a tile on a roof,nbsp;while the outer extremity of the sporangium is close against its inner surfacenbsp;(Fig. 25 B). Sometimes its sharp lower margin projects beyond the topnbsp;of the leaf-base, so that a somewhat peltate attachment results, as in

Lindley and Hutton (1), vol. iii, t. 163, Stur (5), p. 233.nbsp;nbsp;nbsp;nbsp;^ Binney (1). n, tt. 9, 10.

Binney�s^ figures, in one of which�*, owing to an erroneous conception of the crowded organs, the sporangium appears attached to the under sidenbsp;of the leaf-cushion. The sporangium in question evidently belongs to annbsp;adjacent leaf-base from below. Stur states that the lamina of these sporo-phylls drops off, as in the vegetative branches, leaving behind it a transverselynbsp;rhombic scar-surface with a distinctly defined bounding line, and cites Lepi-dostrobus Goldenbergii � as an example, and such in fact appears to be thenbsp;case in that species. Certain figures of Lesquereux, his Lepidostrobusnbsp;macrocystis for example are perhaps to be understood in a similar way,nbsp;but his treatment of them is so summary that it is impossible to speak withnbsp;any certainty without a knowledge of the original specimens. But on thenbsp;other hand, in a very large number and indeed in the vast majority of Lepi-dostrobi, the lamina does not regularly separate from the base of the leaf,nbsp;but remains firmly attached to the sporangiferous cushion, or is torn fromnbsp;it only occasionally and more by chance and irregularly.

It is of course seldom possible to observe all the above details on the impression of a single cone, and only when it is broken up in differentnbsp;planes. I have before me a specimen of the kind from Dutweiler, whichnbsp;shows quite unanswerably that all the forms of preservation which we arenbsp;about to examine simply represent different sections through the samenbsp;organs. Seen from without Lepidostrobi look very like fir-cones ; we seenbsp;nothing but the lanceolate laminaequot; of their scales, which lie one over thenbsp;other like tiles on a roof. The median fracture is more instructive; in thisnbsp;the axis is seen beset with crowded linear protuberances, the bundle-tracesnbsp;of the cast, when the rind formed from the leaf-cushions is removed. Thenbsp;lateral leaves are then seen in longitudinal section ; they are distinctlynbsp;shown in most cases as fine shining strips of coal in the stone, and thenbsp;splintering of the stone will sometimes wholly or partially expose thenbsp;surface of a lamina. The sporangia are particularly well and clearly seennbsp;as a rule in this view; they lie above the leaf-line like thick cushionsnbsp;usually filled with the stony material and .surrounded by a thin rind ofnbsp;coal, as will be seen in Binney�s � and in Brongniart�s � figures. Anothernbsp;common mode of fracture is also shown in Binney�s figure just mentioned,nbsp;where we look down from above on the outer extremities of the sporangia.nbsp;The opposite face would have shown from the inside either the base of allnbsp;the laminae of the leaves, or the apices of the cushions, according to thenbsp;direction of the fracture. On a counter impression of this kind, which Inbsp;found in the Gegenort mine at Dutweiler, I observe on several of the leaves,nbsp;close to where the line of fracture passes through their bases, a small ob-

tusely triangular scar with a trace-point in its centre, which from its median position is probably the object discovered by Stur on the barren cushion,nbsp;and called by him the ligular pit. Its occurrence in Lepidostrobi was tillnbsp;now unknown; the very obscure impressions, the only ones on which it cannbsp;be shown, are not often found in the collections. It remains only to mentionnbsp;transverse fractures of the cones, which present the surface-view of thenbsp;sporophylls, and show the whole form of the sporangia on their bases;nbsp;these too are not altogether rare \

The cones are of very various dimensions, from the size of catkins of the hazel to the length of one and a-half feet, with corresponding thickness.nbsp;Cylindrical cones of considerable length are figured for example by Les-quereux ^ as Lepidostrobus princeps, by O. Feistmantel as L. variabilis,nbsp;Ldl. and Hutt., and by Geinitz� under the same name. Remains ofnbsp;cones of great size, remarkable for the unusual thickness of the axis, arenbsp;classed by Lesquereux with Lepidophloios. Weiss � also has describednbsp;a similarly colossal cone as Lomatophloios macrolepidotus, but unfortunatelynbsp;there is no detailed account of it. The enormous size of the axis in thesenbsp;specimens gives rise to a suspicion that the fructification was not confinednbsp;to special fertile shoots, but might occasionally appear on the leaves evennbsp;of the main stem which then increased in thickness, much as we see in thenbsp;present day in the female flower of Cycas, and mutatis mutandis in Lycopodium Selago. We naturally ask, on what sort of scars could such conesnbsp;be seated as lateral organs ?

The leaves too on the cones differ very essentially from one another in form and size. We get a particularly clear view of them when they havenbsp;been torn with the supporting cushion from the cone, and lie as flattenednbsp;impressions on the faces of the stratification. The angle formed by thenbsp;lamina and base of the leaf is in this case pressed flat, but there is an evidentnbsp;parting between them in the shape of a transverse fold or thickening.nbsp;Sporophylls in this state are common enough in some deposits, and arenbsp;named after Brongniart � Lepidophyllum ; but they are rarely found quitenbsp;perfect, and it is generally the upper part, the lamina, which is preserved.nbsp;The lamina varies much in shape; it may be lanceolate, or linear andnbsp;sharply pointed, or it may be broad and contract into an obtuse apex; it isnbsp;always traversed by a conspicuous median nerve, which often becomes broadnbsp;and ribbon-shaped. The base of the leaf also is seen when preserved to benbsp;divided by an evident median nerve into two halves, which are partednbsp;from the lamina by the transverse folds mentioned above. The place ofnbsp;insertion of the sporangium is shown by a strong linear projection on the

� Brongniart (1), t. 23, ff. 5, 6. nbsp;nbsp;nbsp;* Lesquereux (3), vol. ii, t. 45.nbsp;nbsp;nbsp;nbsp;^ Geinitz (5), t. 2.

* Lesquereux (1), vols. i and ii, t. 118, f. 6 and vol. iii, t. 105. nbsp;nbsp;nbsp;� Weiss (4), p. 354-nbsp;nbsp;nbsp;nbsp;� Brong-

median keel (Fig. 35 D). It is only in a few authors that we find more than a superficial notice of these Lepidophylla, which were usually taken,nbsp;even by O. Feistmantel \ for example, and by Stur for vegetative leaves,nbsp;but were recognised as sporophylls by Goldenberg and Schimper. Evennbsp;good figures are scarce, those especially which show the base of the leafnbsp;attached to the lamina ; some examples will be found in Goldenbergnbsp;O. Feistmantel^ Lesquereux� and Schimper�, and also in Geinitz h Thenbsp;large forms with obtuse terminations to the laminae evidently belong tonbsp;cones of gigantic size, and agree in habit with those figured by Lesquereuxnbsp;in the fructification mentioned above which he classes with Lepidophloios;nbsp;they occur abundantly with remains of stems of that genus in the neighbourhood of Saarbr�cken, and may be peculiar to it.

All the facts which we have been discussing hitherto, and which are to be observed in the impressions of our plants, are entirely confirmed by thenbsp;examination of silicified specimens; but it is from the latter only that wenbsp;have obtained a complete knowledge of the spores which are contained innbsp;the sporangia, and which could only be studied exceptionally and imperfectly in impressions. The most important point is, that hetero.spory, suchnbsp;as that of Selaginella, has been distinctly ascertained in several individualsnbsp;of Lepidostrobus. But we must be careful not to draw any general conclusion from this fact, since there may have been isosporous and hetero-sporous families with the same habit among Lepidodendreae, as therenbsp;are in Lycopodiae and Selaginellae in our recent vegetation. We arenbsp;in possession of a number of cones which apparently contain only onenbsp;kind of spores, but these are only fragments of a larger or smaller size. Itnbsp;might be just in the part that is wanting that the other spore-form maynbsp;have been contained, and the suspicion is the more reasonable because innbsp;our Selaginellae, as we know, the macrospores are often confined to a smallnbsp;space at the base of the cone, in Selaginella spinulosa to the lowest sporo-phyll. And even if a perfect cone were ever found with spores of only onenbsp;kind, it might still be objected that the other kind may have been confinednbsp;to different cones on the same plant; it is true that this arrangement doesnbsp;not occur at the present day, but this seems to be no reason why it maynbsp;not have occurred in former ages. But though we cannot expect that thisnbsp;question will ever be certainly determined, yet it will be convenient tonbsp;speak generally of macrospores and microspores, as in well-ascertainednbsp;examples of heterospory, and to include under the word microspores thosenbsp;cases also in which, as we know of no other kind of spores, there maynbsp;have been isosporous as well as heterosporous forms. We will now

Heterosporous cones have been described by Binney � under the names Lepidostrobus Wiinschianus and L. levidensis, the former of which comesnbsp;from Laggan Bay in Arran, the latter from the Carboniferous ironstonenbsp;(Blackband) of Airdrie, in Scotland. It is not stated whether the formernbsp;specimen showed structure, though this is probable from the locality innbsp;which it was found. The second was structureless ; its substance wasnbsp;turned into coal and the spores partly replaced by pyrites. Both specimens are narrowly cylindrical; in both the sporangia on the upper part ofnbsp;the sporophylls contain a fine-grained mass composed of microspores;nbsp;those on the lower part are filled with tolerably large macrospores flattenednbsp;into the forms of disks or plates, and in Lepidostrobus Wiinschianus therenbsp;appear to have been very few of these macrospores in each sporangium.nbsp;The carbonised macrosporangia in Lepidostrobus levidensis are of preciselynbsp;the same character as those of a fructification also found at Airdrie, whichnbsp;had been previously described by Carruthers^ as Flemingites, and thenbsp;identity of this form with Lepidostrobus is also vouched for by Kidston �,nbsp;who examined the original specimen in the British Museum. The creationnbsp;of this new genus was due to the fact that Carruthers, owing to the entirenbsp;disappearance of the walls of the sporangia, mistook the macrospores fornbsp;so many sporangia, which must have been present therefore in great numbersnbsp;on each sporophyll. It may be observed in passing that similar flattenednbsp;macrospores, showing the three edges of their pyramidal apex with greatnbsp;distinctness, are widely disseminated through the coal. They are of verynbsp;various dimensions, being sometimes visible to the unaided eye, and maynbsp;be easily isolated by maceration. Many figures of them have been givennbsp;by Reinsch^, who named them Triletae. Some of these at least certainlynbsp;belong to Lepidostrobi. One much crushed cone from Halifax describednbsp;and figured by Williamson � must be mentioned in this place. Four macrospores disposed in the form of a tetrahedron occupy the sporangia in thenbsp;lower part of the cone. They are of large size, and are provided with annbsp;irregular tubular process at the apex. The exosporium is covered withnbsp;fibrous appendages. The structure of the axis of the cone is essentiallynbsp;that of the type of Lepidodendron Harcourtii. Two other cones are knownnbsp;in the silicified state. One of them, Lepidostrobus Dabadianus, Schpr,nbsp;was found as a loose stone in the department of the Haute-Garonne at thenbsp;mouth of the Volpethal, and was sawn through lengthwise and describednbsp;by Brongniart�. One half is at Paris, the other, formerly in Schimpersnbsp;possession, w�ill now be in the British Museum. The surface of the thick ovoid

� Binney (1), n, t. 11, f. 2 and t. 10, ff. i, 2. nbsp;nbsp;nbsp;^ Carruthers (14).

^ Reinsch (1). nbsp;nbsp;nbsp;^ Williamson (1), x, t. 15, ff. 8-12.nbsp;nbsp;nbsp;nbsp;' Brongniart (8).

cone, which is eleven centimetres in length and five centimetres in breadth, is injured by abrasion, the points of the leaves are gone, and a roundish protuberance corresponds to the extremity of each sporophyll. The sporangianbsp;filled with globular macrospores are replaced in the upper part of the conenbsp;for about two-fifths of its length by microsporangia, the spores of which arenbsp;connected together in fours. Nothing can be learnt about the character ofnbsp;the axis from Schimper�s ^ or Renault�s ^ figures ; it may have been destroyednbsp;in a great measure by the longitudinal section. There is great resemblancenbsp;between Lepidostrobus Dabadianus and two fragments of unknown origin,nbsp;which have only microspores connected together in tetrads in their sporangia,nbsp;and which were united bySchimper� under the name of Lepidostrobus Brownii.nbsp;One of them passed some time since from the collection of Baron Rogernbsp;at Paris into the British Museum, and a transverse section of it is in thenbsp;Paris Museum. It was described and figured by R. Brown ^ under thenbsp;name Triplosporites. The other specimen, one half of which is in thenbsp;British Museum, the other in the collection of the Jardin des plantes atnbsp;Paris, was originally purchased at a curiosity-shop in Paris, and was longnbsp;in Schimper�s possession. The structure of both these specimens agreesnbsp;perfectly with that of Lepidostrobus Dabadianus, and the abrasion of itsnbsp;surface is still greater (Fig. 25 A, B). The axial strand which is surrounded by numerous transverse sections of leaf-traces has the structurenbsp;of Lepidodendron Harcourtii. Another similar small fragment of a conenbsp;containing only microspore-tetrads was found near Cabri�res in the department of H�rault and was described as Lepidostrobus Rouvillei�. Twonbsp;fragments of the kind showing in their axes the type of Harcourtii, andnbsp;both coming from the calcareous nodules of Oldham, have been figured bynbsp;Binney�, and a number of broken pieces of cones have been described bynbsp;Hooker�^. The latter came from the Carboniferous ironstone of Wolverhampton near Birmingham, and .some of them were found inside stems ofnbsp;Lepidodendron which have the bark still well preserved, having been conveyed into them by the action of water. From specimens now in thenbsp;Jermyn Street Museum in London I have been able to satisfy myself, thatnbsp;in some cases the axile strand of the hollow stem is still present, and showsnbsp;the structure of Lepidodendron vasculare. The same structure is alsonbsp;apparent in the axis of one of the cones, in the rest the central portions arenbsp;too imperfectly preserved. The structure and character of the stems andnbsp;of the fructifications inclosed in them have been illustrated by extraordinarynbsp;drawings. In some specimens the shortly lanceolate leaf-tips are preserved.

The walls of the sporangia are unusually thin, being formed of a single layer of palisade-like cells; the isolated microspores (?) which they containnbsp;are globular; the edges of their pyramidal apices are winged, and are produced at the basal extremity into spreading triangular teeth (Fig. 25 C). Itnbsp;was remarked above that Williamson^has found fragments of cones in thenbsp;plant-petrifaction of Burntisland, along with branches and stems of his Lepi-dophloios brevifolius, and that he assigns them to the vegetative remainsnbsp;as their fructifications. The microsporangia were only met with in onenbsp;instance along with the other parts, and then they occupied as usual thenbsp;basal portions of the cones. Their spores are large and clothed all roundnbsp;with a close array of curved filiform membranous processes. In one figure ^nbsp;Williamson gives a tangential section, which passes through the upper partnbsp;of the strobilus where the microspores are concealed, and shows the rhombicnbsp;transverse sections of the sporophylls with wings on both sides exceedinglynbsp;well. These are provided on the under side with a wing-like processnbsp;answering to the median bundle, and on the upper side bear the sporangium,nbsp;the narrow insertion being plainly seen in the middle of the lamina. Thenbsp;sporangium has its wall formed of one layer of cells, and is filled insidenbsp;with a great number of small microspores united together in fours.

The only form which remains to be mentioned is an imperfectly known strobilus, which Williamson� has described from materials found near Oldham and Halifax ; here the macrospores are the only spores that arenbsp;known, and they are marked by sundry peculiarities. That this fossilnbsp;belongs to Lepidodendreae is rendered very probable by the spiral notnbsp;verticillate position of its sporophylls, and by the presence of only onenbsp;sporangium over the transverse section of each scale, as the tangentialnbsp;section shows k The structure of the axis is not to be seen in the specimens which have been figured ; but I find from a preparation, for which Inbsp;am indebted to Mr. Cash, that it resembles that of Lepidodendron Har-courtii. The macrospores have the usual tetrahedral form, the edges of thenbsp;sides of the pyramids project strongly, and the base is convex; but theynbsp;are furnished with a hollow bladder-like appendage, which runs across thenbsp;middle of the basal surface like a curved tube, and evidently represents annbsp;organ analogous with the air-sacs of the pollen of the pine. If the spore isnbsp;cut through in a direction parallel to its length, it appears of course as anbsp;broad one-sided wing. Transverse sections pass through it twice at its twonbsp;extremities, and then there appear to be two hollow bladder-like appendages opposite to one another. Williamson also states that he has found anbsp;large number of minute cells inside the spores, but he says nothing precisenbsp;about their nature. I have certainly seen these cells in the preparation

which I possess, and in those which I had the opportunity of examining in Mr. Cash�s collection, but they appeared to me to be connected togethernbsp;and to form an internal and tolerably voluminous cell-structure, which wenbsp;should be inclined to compare with the inner cell-complex in the pollen ofnbsp;Gymnosperms and Cordaiteae, and with the early tissue-formation in thenbsp;microspores of Selaginella. We cannot at present say anything furthernbsp;or more definite respecting this apparently rare fossil; we must await thenbsp;discovery of other and better specimens.

XI.

It has been observed above in describing Lepidodendron, that the Sigillariae rank next to that genus from the similarity of the surface-character of their stems, and indeed come so near it, that certain species havenbsp;repeatedly given occasion to confusion between the two groups. Unfortunately we are not so well acquainted with the development and structurenbsp;of all the separate parts of the plants in Sigillarieae as in Lepidodendreae:nbsp;fragments of stems are extremely abundant in the form of impressions andnbsp;casts, but as regards the anatomical structure, the fructifications, and evennbsp;the foliage leaves, we have to be content with the information to be derivednbsp;from a few scanty remains. The duration of Sigillarieae in the series ofnbsp;formations resembles that of Lepidodendreae, but is still more limited.nbsp;Sigillarieae disappear with Lepidodendreae in the Rothliegende, havingnbsp;been found in the lower members of that formation near Autun, near Olten-dorf in Bohemia^, and near Schmalkald ; but they do not make theirnbsp;appearance before the beginning of the Coal-measures, and are stillnbsp;extremely rare in its lowermost deposits, in the Millstone Grit for example.nbsp;They appear in great abundance, and as the dominant form of vegetationnbsp;only in the middle deposits of this period, as in the Schatzlar and Saar-briicken beds. Stur ^ has put together a number of species from the basenbsp;of the whole formation. Some older remains supposed to belong to thenbsp;group are mentioned by G�ppert but they are more than doubtful. Thenbsp;same may be said not only of the form known as Sigillaria Vanuxemii,nbsp;G�pp^, from the Chemung (Devonian) beds of Oswego in New York, butnbsp;also and more particularly of his S. Hausmanniana�, which was found bynbsp;Hausmann in the beginning of the century between Idre and Sarna in Norway in supposed Lower Devonian strata. Later authors have rightly determined that this specimen is merely a ripple-mark. In the other directionnbsp;from beds that are more recent than the Rothliegende I only know ofnbsp;one fragment described and figured from the Upper Bunter Sandstone of

Heimbach near Commern in the Eifel, and this is not altogether above suspicion, though Weiss ^ too has recently pronounced in favour of itsnbsp;belonging to Sigillaria. The form in question, Sigillaria oculina is in factnbsp;very like those of the group Leiodermaria, and this is exactly the dominantnbsp;group in the most recent of the deposits which contain any Sigillariae.

Turning to the consideration of the impressions and casts of stems, we find it scarcely possible to give a general account of them, because thenbsp;groups of species, the genera if we choose so to call them, differ so greatlynbsp;from one another. The old genus Sigillaria separates after removal of thenbsp;Megaphytae which were placed in it by earlier authors, Brongniart � fornbsp;example, into the divisions or genera, Rhytidolepis, Clathraria, Favularianbsp;and Leiodermaria. The most peculiar form and the one which departsnbsp;most widely from the habit of Lepidodendreae is Rhytidolepis, and it maynbsp;therefore be placed first in the list. Here the entire surface of the stem isnbsp;formed of peculiar broad vertical ribs, which bear the leaf-scars on theirnbsp;flatly convex dorsal surface, and are separated from one another by shallownbsp;but acute-angled furrows. The arrangement of the leaves has been specially studied by Goldenberg^ and Stur�. The latter seeks to prove thatnbsp;the longitudinal ribs do not correspond to the orthostichies, but represent anbsp;system of parastichies which by a peculiar displacement has passed into anbsp;vertical position. In that case we should not have, as appears at first sight,nbsp;a succession of somewhat irregular many-leaved alternating whorls, but thenbsp;relative positions of the leaves would be as in Lepidodendron, only alterednbsp;by displacement, and with a divergence which was determined in one casenbsp;to benbsp;nbsp;nbsp;nbsp;Stur�s publication will give further information on this point;

here we will add only that he � also occasionally found a distinct appearance of orthostichies in Lepidodendron, and that he refers this also to one of the steep oblique line-.systems and explains it by displacement. Lepidodendron costatum is a similar impression Various other irregularitiesnbsp;occur in the position of the leaves, and are not unconnected with the factnbsp;that new ribs, ending blindly below, suddenly and not unfrequently makenbsp;their appearance between the old ones in stems of Sigillariae ¹.

The longitudinal ribs of the stem of Rhytidolepis originate in the coalescence of the leaf-cushions which stand vertically one above another.nbsp;When the coalescence is very perfect, the scars of the laminae of the leavesnbsp;lie at regular distances on the smooth uniformly convex surface of the ribs,nbsp;and the separating furrows are simply straight lines (Fig. 26 A). In proofnbsp;of this we may point to Sigillaria Voltzii in the long list of Brongniart�s �nbsp;figures. But an indication of the separate leaf-cushions which have united

Weiss (9). Blanckenhorn (1), p. 132; t. 20, f. 9. nbsp;nbsp;nbsp;� Brongniart (1).nbsp;nbsp;nbsp;nbsp;' Goldenberg (1).

� Stur (5), p. 293. nbsp;nbsp;nbsp;� Stur (5), t. 23, f. 2.nbsp;nbsp;nbsp;nbsp;� Lesquerenx (3), vol. ii, t. 44, f. 7.nbsp;nbsp;nbsp;nbsp;¹ Weiss

to form ribs is very often shown in the serpentine course of the furrows, which is due to the circumstance that the cushions are broadest at the insertion of the leaves and narrow downwards, so that every leaf-scar lies onnbsp;a knot-like swelling of the rib. This is also accompanied in most casesnbsp;with a regular alternation of greater or slighter elevation above the surface.nbsp;An excellent example will be found in Sigillaria contracta k All possiblenbsp;intermediate cases between these extremes are of course to be seen. Thenbsp;group has received its name from the polygonal leaf-scars, which look likenbsp;the impressions of seals. These scars are considerably larger than those ofnbsp;Lepidodendrae, and by flattening of the two median angles to a greater ornbsp;less extent they become more or less decidedly hexagonal, sometimesnbsp;almost round or ovate. Thenbsp;hexagon will be broader ornbsp;longer according as thenbsp;median or lateral boundarylines are the longer. Differences of this kind arenbsp;generally employed, to distinguish species. The details of the surface of thenbsp;scar can usually be seennbsp;best in mould-specimensnbsp;after the remains of thenbsp;coal have been removed,nbsp;only rarely in the cast; theynbsp;appear in more than usualnbsp;perfectness when the entirenbsp;thickness of the rind of coalnbsp;has separated with themnbsp;from the mould. The tracenbsp;does not lie as in Lepido-dendron on the lower margin of the scar, but in the

middle of the scar or somewhat above the middle. It consists of three small protuberances or impressions, the middle one of which is punctiform or anbsp;little elongated transversely and represents the scar of fracture of the vascularnbsp;bundle. The lateral marks are as a rule elongated into the shape of anbsp;stroke or comma, and diverging below deviate from the vertical direction.nbsp;In some instances, as for example in a stem of Sigillaria elegans fromnbsp;Anzin which lies before me, the deviation may be so great that the marksnbsp;may become almost horizontal; usually they enclose the middle trace-

point, so that it appears to be in brackets. The organisation of the cortical tissue, which lies at the foundation of these two marks, will have to be considered further on ; but of one thing there can be no doubt, that they arenbsp;not essentially distinct from the similar structures in Lepidodendrae, andnbsp;that considering the variations in form to which they are subject in bothnbsp;groups we shall scarcely be able to found a differential character upon them,nbsp;as Renault ^ has attempted to do. In addition to these three marksnbsp;wrinkles more or less strongly marked are to be observed on the surface ofnbsp;the scars, radiating generally from them to the periphery and running eithernbsp;a straight or an undulating course. The strongest of these are apt tonbsp;attach themselves to the mark and to run in the direction of the mediannbsp;plane. The whole surface of the scar between the wrinkles appears whennbsp;the preservation is particularly good to be finely shagreened, evidently thenbsp;impression of the individual cells. In many cases the leaf-scars are as broadnbsp;as the ribs and extend from one lateral furrow to another, in other casesnbsp;they are much narrower than the ribs and occupy only a portion of theirnbsp;convex surface. Dawson ^ has attempted to separate the latter forms asnbsp;belonging to Sigillaria sensit strictiori from the others, which he leaves withnbsp;Rhytidolepis ; to the latter division belongs also Renault�s � section Polle-riana, founded on Brongniart�s ^ Sigillaria Polleriana, S. Deutschiana andnbsp;similar forms. Longitudinal striation and furrowing of the dorsal surfacenbsp;of the ribs is a common phenomenon in these broad-ribbed forms. Furthernbsp;the leaf-cushions which coalesce to form a rib differ considerably in length,nbsp;as has been already said, and the scars therefore are separated by verynbsp;unequal distances. If the leaf-scars are far apart, the portions of the dorsalnbsp;surface of the rib which lie between them are very commonly marked withnbsp;transversal and more or less developed folds and wrinkles, and then if thenbsp;preservation is sufficiently good a minute pit is often to be seen close abovenbsp;each leaf-scar, and a feathery tuft of delicate markings proceeds from thenbsp;pit and spreads in every direction. Stur who was the first to draw propernbsp;attention to this peculiarity, sees in it the homologue of his ligular pit innbsp;Lepidodendrae, and cites some of the figures from various authors � whichnbsp;show this small depression. It should be observed however that the figuresnbsp;in Germar's twenty-fifth table represent forms from the groups Clathrarianbsp;and Leiodermaria ; a figure from Lesquereux ^ may be added to the list.nbsp;If the leaf-scars are nearer together, the surface of the cushions necessarilynbsp;grows smaller. Even in distinct Rhytidolepis-forms we not unfrequentlynbsp;observe indications of transverse boundary-lines of the cushion in the form

' Renault (2), vol. iii, Inti od. p. 4. nbsp;nbsp;nbsp;Dawson (8).nbsp;nbsp;nbsp;nbsp;^ Renault (2), vol. i, p. 134.

* Brongniart (1), t. 165. nbsp;nbsp;nbsp;� Stur (5), p. 293.nbsp;nbsp;nbsp;nbsp;� Brongniart (1), vol. i, t. 144, f. 4;

Goldenberg (1), t. 9, f. 4 ; Germar (1), t. il, f. 2, and t. 25, ff. i, 2. nbsp;nbsp;nbsp;� Lesquereux (1), vols. i,

of flat transversal furrows running above the scars. If these furrows become deeper and more distinctly marked, and the scars are at the same time morenbsp;crowded together on the rib, then each cushion projects more decidedlynbsp;beyond the dorsal surface of the rib, and we have the character of Favu-laria (Fig. 26 B), the type of which is seen in Sigillaria elegans ^ and S.nbsp;tessellata 2. In these forms the sharply polygonal leaf-scars, raised on conspicuous cushions above the common projecting rib which bears them, arenbsp;crowded together till they touch one another; they alternate in the adjacent rows, and as they occupy the entire breadth of the rib their lateralnbsp;angles are thrust a little in between one another, and the bounding furrowsnbsp;are slightly bent into a zigzag line. Species, in which the transverselynbsp;separated cushions are somewhat farther removed from one another, arenbsp;intermediate between Rhytidolepis and Favularia; such are Sigillarianbsp;Dournaisii� and S. Knorrii'*. Lastly the transversal separation of thenbsp;cushions may go so far, that the rib on which they are placed disappears ornbsp;becomes quite inconspicuous, and then we have the Clathrariae (Fig. 26 C)nbsp;or, as Weiss names them, the cancellate Sigillariae. If even in Favularianbsp;two systems of parastichies are distinctly apparent by the side of thenbsp;orthostichy, this is still more decidedly the case in Cancellatae. In addition to this a considerable increase in breadth takes place in the transversenbsp;direction in the cushions of Cancellatae ; they become rhombic in form andnbsp;thrust themselves laterally with their acute angles in between their neighbours, so that the parastichies are sometimes more distinctly apparent thannbsp;the orthostichies. There may then be great resemblance in habit to Lepido-phloios, with which genus, as has been already mentioned, these forms havenbsp;often been confounded ; but the size of the leaf-scar and the equal growthnbsp;of the cushion in every part make it easy as a rule to distinguish them ifnbsp;carefully examined from Lepidophloios, in which the upper facets of thenbsp;cushion are excessively developed. The following figures of typicalnbsp;Clathrariae may be cited: Sigillaria Defrancei S. Brardii �, and S.nbsp;Menardi^.

While Rhytidolepis, Clathraria and Favularia are linked together by intermediate forms, this cannot be said of Leiodermariae (Fig. 26 D),nbsp;in which the leaf-cushions as such are entirely wanting, and the leaf-scarsnbsp;are set on the perfectly level surface of the rind and at wide distances fromnbsp;one another. From among the figures of this group may be mentionednbsp;Brongniart�s Sigillaria leioderma, S. obliqua and S. venosa also S. lepido-dendrifolia� and S. spinulosa The finest representation of a form of

� Brongniart (1), vol. i, t. 146, f. i. nbsp;nbsp;nbsp;^ Brongniart (1), vol. i, t 156, f. i. ^ Brongniart

(1). t. 153, f. 5 ; GoMenberg (1), t. 7. nbsp;nbsp;nbsp;* Brongniart (1), t. 156, ff. J, 2.nbsp;nbsp;nbsp;nbsp;� Brongniart

(1), vol. i, t. 159, f. I. nbsp;nbsp;nbsp;� Brongniart (1), t. 158, f. 4; Germar (1), t. ii, ff. i, 2 ; Goldenberg

(1), t. 7 ; Weiss (1), t. 16. nbsp;nbsp;nbsp;� Brongniart (1), t. 158, ff. 5, 6.nbsp;nbsp;nbsp;nbsp;' Brongniart (1), t. 157.

this kind (S. spinulosa) we owe to Germar^. The Leiodermariae bear much the same relation to the preceding forms as Bothrodendrae bearnbsp;to Lepidodendrae; they are separated from them on the whole in timenbsp;also, being chiefly found in the most recent formations that contain anynbsp;Sigillarieae, though Goldenberg has obtained a few of them, but rarely,nbsp;from the beds at Saarbriicken. In the specimen of Sigillaria spinulosanbsp;figured by Germar the entire surface is rough with small anastomosingnbsp;folds; its leaf-scars show the characteristic trace in the normal manner.nbsp;Close under the upper margin of the trace lies the ligular pit as a minutenbsp;point, and beneath each pit are other marks, in which the depressed centrenbsp;is surrounded by a circular wall. Ordinarily there are two of these marksnbsp;standing right and left of the median plane; sometimes only one mark isnbsp;present in a lateral position, and occasionally there are none. They occupynbsp;exactly the positions of the two marks in Lepidodendron, and are thereforenbsp;compared with them by Stur, though nothing of the kind is known innbsp;other Sigillarieae. Germar had regarded them as the points of attachmentnbsp;of prickles. Zeiller^ and Renault� consider them to be the scars ofnbsp;adventitious roots. Renault gives a figure of Sigillaria spinulosa innbsp;which they are distributed in groups, and do not occupy the regularnbsp;position, as in Germar's specimen. Further investigation is desirable, butnbsp;I have not the necessary material. Whether Semapteris carinthiaca�nbsp;from the anthracites of Carinthia belongs to Leiodermariae I cannotnbsp;positively say from the figure only. The cushions on the smooth surfacenbsp;of the stem are far apart from one another and are somewhat decurrent;nbsp;their scars certainly are like those of Sigillaria. Semapteris tessellata,nbsp;also described in Unger�s work, may be a badly-preserved form of Clathra-riae. Unger indeed would place not only these two forms but all thenbsp;Clathrariae as well with Ferns; of Leiodermariae he does not speak withnbsp;perfect distinctness.

Hitherto we have been speaking only of the surface-impressions. In a cast these can be examined only, as was said above, when the whole ofnbsp;the rind of coal is preserved. If this is removed, there remains behind annbsp;inner impressed surface answering to some extent to the casts of Lepidodendrae, which are beset with linear bundle-traces. The surface of thisnbsp;impression is quite smooth in Leiodermariae, but the vertical ridges arenbsp;plainly seen upon it in Rhytidolepis. But the leaf-trace is marked in bothnbsp;cases by three protuberances, not by one as in Lepidodendrae; the smallnbsp;middle one it is true is often very indistinct, while the two lateral onesnbsp;appear plainly as parallel strokes. In those Rhytidolepis-forms whichnbsp;have very broad ribs and narrow leaf-scars, such as Sigillaria reniformis �

' Germar (1), t. 25, ff. i, 2. nbsp;nbsp;nbsp;* eiller (3), p. 138.nbsp;nbsp;nbsp;nbsp;� Renault (2), vol. i. * Renault

(2), vol. i, t. 17, f. 2. nbsp;nbsp;nbsp;� Unger (10), t. 3, f. i.nbsp;nbsp;nbsp;nbsp;� Brongniart (1), vol. i, t. 142.

and S. laevigata^, these parallel trace-lines may attain a considerable breadth and become alrnost ovoid, and moving apart from one anothernbsp;may leave a distinct space between them. Such casts were regarded bynbsp;the older authors as a separate genus and named Syringodendron, Stbg.nbsp;In these specimens the ribs are usually marked with fine longitudinalnbsp;striae, which are shown with especial clearness on the mould of the surface,nbsp;in those places in which the rind of coal remains attached to it and showsnbsp;us its inner side. How far it is the case that other casts than these occurnbsp;in Sigillariae, answering to some extent to Bergeria-forms in Lepido-dendrae, is a question which deserves further enquiry. We might concludenbsp;from Renault�s^ figure that Sigillaria microstigma, Br. is such a form ofnbsp;preservation belonging to S. tessellata, but since our information aboutnbsp;them is scanty, and I have never myself seen any specimens, I must refrainnbsp;from giving a decision. Since, as will have to be shown later on, Dicty-oxylon-structure of the rind has been observed in some Sigillariae, there cannbsp;be no doubt but that some of the impressions which answer to this structurenbsp;(Fig. I on p. 7, Fig. 22 B on p. 217) will belong to the group which we arenbsp;considering, though we may not be able to distinguish them from the rest.

The stems of Sigillariae are accompanied by large numbers of long linear leaves with a keel formed by the strongly projecting median nerve. Itnbsp;is usually assumed that these leaves belong to Sigillariae, and appeal is madenbsp;to a few discoveries, which though not absolutely proving the connectionnbsp;yet are calculated to render it very probable. In these instances leavesnbsp;of the above description were found lying apparently in their naturalnbsp;position and nearly parallel with one another upon and close to portions ofnbsp;Sigillaria-stems. But absolute proof is still wanting, for, as far as I know,nbsp;the attachment of the leaf to the scar of the cushion has never yet beennbsp;certainly observed. It is remarkable how rare such specimens seem tonbsp;be, and I can only cite a very few figures from the literature, thoughnbsp;Renault� states that portions of Sigillaria elegans, S. rhomboidea andnbsp;S. Brardii with leaves are preserved in the Paris Museum. The best-known figure is that of Sigillaria lepidodendrifolia in Brongniart^; a similarnbsp;figure of S. Cortei, which belongs to Rhytidolepis, is given in Geinitz�.nbsp;The figures of S. rimosa, Goldbg and S. aequabilis, Goldbg supplied bynbsp;Goldenberg� are less convincing. From the circumstance that pieces ofnbsp;stem only of Sigillariae have hitherto been found, never any leafy branchesnbsp;such as are so abundant in Lepidodendrae,it maybe concluded that Sigillariaenbsp;must have had their branch-system very slightly developed, and the conclusion is supported by the great scarcity of pieces in which branching cannbsp;be perceived. Wherever it has been observed it is found to be truly

' Brongniart (1), vol. i, t. 143. nbsp;nbsp;nbsp;� Renault (2), vol. i, t. 17, f. 3.

dichotomous. Weiss in the year 1869 could only cite three figures of these branched stem-fragments, two of which belong to Sigillaria hexagona^ andnbsp;one to S. elegans^, and not one of these figures is quite above suspicion.nbsp;Dawson�s drawing is too small and too imperfect, and the others do notnbsp;clearly show the line of separation on the inner side between the twonbsp;branches, which terminate here with the zigzag bounding line of a longitudinal rib. These figures may therefore be quite as well explained bynbsp;supposing that a simple piece of stem had been separated by crushing intonbsp;two parts. Little more has been added since that time as far as I know.nbsp;But we have at last an absolutely certain and convincing case in Sigillarianbsp;Eugenii, Stur, from the Culm (Ostrau beds), which has been studied bynbsp;Stur�. Here the mould and the cast of the bifurcating stem are bothnbsp;preserved, and it is stated that we have similar remains also of Sigillarianbsp;Brardiik

While there can therefore be no doubt of the occurrence of dichotomous branching in Sigillariae, it can also be shown on the other hand thatnbsp;certain stems were simple and unbranched throughout. Much the mostnbsp;important specimen of this kind was found in constructing the Friedrichs-thal tunnel in the mountain-district of Saarbriicken, and was examined bynbsp;Goldenberg. There is the more reason to regret that a connected accountnbsp;of the fossil has never been published, and that we are still dependentnbsp;on the scattered occasional notices of this author. He says�: �Thusnbsp;among other things in the construction of the railway near Neunkirchennbsp;a regular forest of Sigillariae was exposed to view in the state in whichnbsp;it lived and had its being. The roots of these plants lay on the samenbsp;geological level, and the stems were still in their original erect positionnbsp;on this their old ground and soil. Most of these stems belonging to thenbsp;Sigillariae with broadly-fluted rind, Sigillaria reniformis, amp;c., were fromnbsp;two to three feet in diameter at the base, and ended above in a roundednbsp;apex without showing any sign of branching.� Two only of these completenbsp;stems have been figured�. The first of them, belonging to Sigillarianbsp;reniformis, was rooted in the ground, was from five to six metres in height,nbsp;and was unusually thick. Quite unbranched it contracts rather suddenlynbsp;into a dome-shaped termination. The other, Goldenberg�s'^ Sigillarianbsp;cactiformis, which is afterwards merged in the allied form S. reniformisnbsp;and is not mentioned again, is broken off above the root-system, but hasnbsp;its apex well preserved and fashioned as in the preceding species. In itsnbsp;upper portion occurs the interpolation, mentioned above On p. 242, of fournbsp;longitudinal ribs. Its dimensions are however much smaller; it is eighteen

inches high and nine inches thick at the base. Two other stems, also figured in Goldenberg', seem to have been longer and more cylindrical.nbsp;As they are broken across at the upper end, they have nothing to do withnbsp;the present question. We may also reserve for the succeeding chapternbsp;any further notice of the many stumps of trees broken short off, and of thenbsp;bases of stems which are rooted in the ground and whose subterraneannbsp;organs have proved to be Stigmariae. They have become known to usnbsp;from very various parts of the Carboniferous formation.

Every one who has collected much even on the refuse coal-heaps is sure to have met with fragments of Sigillariae, in which the regularity of thenbsp;ribs and their leaf-cushions is seen to be completely disturbed over portionsnbsp;of the surface. Closer examination shows that this is due to the presencenbsp;among the regular rows ofnbsp;intrusive scars of a differentnbsp;character, between which lie thenbsp;ribs in their normal condition,nbsp;except that they are slightlynbsp;curved and sinuous. Brong-niart^ had himself figured suchnbsp;a piece of Sigillaria Knorrii,nbsp;though not a very markednbsp;specimen of the kind, but henbsp;saw in it only a casual irregularity. Schimper� was thenbsp;first to give a full account ofnbsp;the matter in describing hisnbsp;Sigillaria Lalayana (Fig. 27),nbsp;and suggested that the organsnbsp;of fructification may have beennbsp;seated on these scars. Therenbsp;is very much to be said for thisnbsp;idea/since the plants have sonbsp;few branches and these organs must have been attached somewhere,nbsp;and all later authors seem to have adopted it. Other good figures ofnbsp;specimens of the kind will be found in Zeiller^, Renault� and Williamson�.nbsp;The shape of the scars in question varies; it may be circular or elongatenbsp;and angular, and the point may be supposed to be unimportant since itnbsp;depends directly on the contact with adjoining scars and with the ribs whichnbsp;bear them. They are in fact of circular form in Sigillaria spinulosa, the

only Leiodermaria in which they are known and this is the effect of lateral contact at every point owing to the peculiar character of the surface.nbsp;They are polygonal on the other hand and elongate, as far as is known,nbsp;in Rhytidolepis and Favularia. Sigillaria Brardii is the only species in thenbsp;group of Cancellatae in which scars of this kind have as yet been found;nbsp;here according to Zeiller�s^ fine figure the scars are isodiametricallynbsp;polygonal, and if they are represented as circular in Renault^ this maynbsp;very well be explained by the imperfectness of the figure. Williamson�snbsp;description cited above, which belongs according to Renault^ to thisnbsp;species, agrees essentially with that of Zeiller. The character of thenbsp;surface of the scar, which projects convexly in the mould, is quite differentnbsp;to that of the leaf-scar. In its centre is a circular protuberant trace ofnbsp;considerable dimensions, and the entire periphery is occupied by stoutnbsp;sinuous radiating wrinkles, between which there are usually fragments ofnbsp;coal still adhering. We should no doubt be able to see other details onnbsp;the surface of the rind of coal on the cast; but though I have myself foundnbsp;several good specimens of moulds, a well-preserved cast of the kind has notnbsp;yet fallen in my way.

Authors have described a number of species of Sigillariae, all of which are distinguished by the form and character of the leaf-cushions. Thenbsp;method is very precarious, for we cannot say to what extent alterationsnbsp;supervene with the growth of the plant. The scars of the fructification arenbsp;known as yet in very few forms, and yet distinctions have been alreadynbsp;observed in their distribution on the surface of the stem, and these seem tonbsp;supply characteristic marks. From this source we may expect to obtainnbsp;much help in arranging the group, as Zeiller� has very conclusively shown,nbsp;if we can once arrive at more extended knowledge through further research.nbsp;So far as we can venture to generalise from our present scanty knowledge,nbsp;the scars of the fructification are confined in Rhytidolepis and Favularia tonbsp;more or less broad intercalary zones, which form rings round the stem.nbsp;Within these zones the scars, touching one another above and below, formnbsp;vertical rows inserted between the ribs in Sigillaria tessellata�, in S.nbsp;Lalayana, Schimp. (Fig. 27), and in Sigillaria Lorwayana'^. In thesenbsp;species they are nearly rectangular through mutual pressure. On thenbsp;determination of species by authors I do not venture to express an opinion ;nbsp;but I may call attention to the great resemblance between the two figuresnbsp;first cited. The scars are developed in a broad transverse zone betweennbsp;the ribs, and being everywhere isolated they are elliptical in form or two-

' Renault (2), vol. i, t. 17, I 2. nbsp;nbsp;nbsp;^ Zeiller (1), t. 174, f. i. * Renault (2), vol. 1, t. 17, f. i-

�* Renault (2), vol. ill, p. 9. nbsp;nbsp;nbsp;� Zeiller (12).nbsp;nbsp;nbsp;nbsp;� Zeiller (1), t. 173, f. 2.nbsp;nbsp;nbsp;nbsp;�� Dawson

angled in Sigillaria scutellataS. mamillaris and S. alveolaris�. S. Knorrii, Brongn. also (see above on p. 345) and S. oculata^ appear tonbsp;belong to this group. I also find them so arranged in several piecesnbsp;of Rhytidolepis in my collection. Lastly the scars appear from thenbsp;figures to be placed not in broad zones of the circumference of the stem,nbsp;but in single widely-separated circles, in Sigillaria Brardii and S. spinulosanbsp;(see the figure cited above on p. 346), the only species of Clathraria andnbsp;Leiodermaria in which they are known. Renault � says that they mustnbsp;have been arranged in these two species � in a spiral with more or le^snbsp;distant turns �; I have never had the opportunity of seeing them myself.

Authentic remains of Sigillariae with the structure preserved are extremely rare. A single diminutive fragment of a small stem of Sigillarianbsp;Menardi is all that is at present known from the group of Cancellatae.nbsp;This specimen was made use of by Brongniart� for his famous monograph,nbsp;and it was there described under the name of Sigillaria elegans, but Zeillernbsp;has proved that this is a wrong determination and that it belongs tonbsp;S. Menardi. S. elegans does not generally occur in deposits so recentnbsp;as those which contain the siliceous fragments of Autun, from which thisnbsp;specimen was obtained. The transverse section of it shows a broadnbsp;medullary tube, but the tissue has disappeared and been replaced by anbsp;homogeneous mass of silica. The tube is immediately surrounded by anbsp;ring of many crescent-shaped strands of tracheides, which have their convexity turned inwards and are in lateral contact with one another, and innbsp;which the narrowest elements are in the concavity of the outer side.nbsp;The strands appear to be entirely composed of scalariform tracheidesnbsp;of considerable length. The leaf-trace-bundles join them on their outernbsp;side. This ring is surrounded by a mass of secondary wood which isnbsp;divided into separate wedges by primary medullary rays, and each wedgenbsp;corresponds to one of the inner bundles. This woody mass is of perfectlynbsp;normal character, and like the secondary wood of Cycadeae is divided bynbsp;fascicular rays into many narrow plates, in which the transverse sections ofnbsp;the scalariform tracheides are arranged in regular radial rows. The leaf-trace-strands run almost horizontally through the secondary wood, and itnbsp;is not till they reach the rind that they begin to ascend in steep curves.nbsp;The consequence is that they pass through the wedges of the wood verynbsp;nearly in the transverse direction, so that if the transverse section encounters one of them, the wedge of wood is seen to be divided by it into twonbsp;parts, as is shown in Fig. 38 and in Brongniart�s � and Renault�s ^ figures.nbsp;Little of the cortical tissue is preserved in our specimen; the inner and

' Zeiller (1), t. 173, f. i. nbsp;nbsp;nbsp;� Lesqtiereux (1), vols. i, ii, t. 72, f. 5.nbsp;nbsp;nbsp;nbsp;� Goldenberg (1),

t- 7, f. i6. nbsp;nbsp;nbsp;* Geinitz (1), t. s, f. lo.nbsp;nbsp;nbsp;nbsp;= Renault (2), vol. iii, p. 9.nbsp;nbsp;nbsp;nbsp;' Brongniart (7).

� Zeiller (12), p. 259. nbsp;nbsp;nbsp;� Brongniart (7), t. 25.nbsp;nbsp;nbsp;nbsp;* Renault (1), t. ii, f. 13-

middle portions are entirely destroyed ; in the inner portion there remain only the transverse sections of the. ascending leaf-traces, and these arenbsp;obtusely triangular in form and have one angle turned towards the outside.nbsp;We shall have to return to the character of the leaf-trace-bundles ofnbsp;Sigillariae in concluding our account of the anatomy of the group. Thenbsp;outer rind which bears the leaf-cushions is preserved; it consists ofnbsp;compact parenchyma and separates into two not very distinct layers, ofnbsp;which the inner is composed of elongated elements disposed in rows onnbsp;the transverse section, the outer of ordinary isodiametric parenchyma.nbsp;The former is always termed in Renault�s publications the � couchenbsp;subereuse,� an expression which must be understood here as in Lepi-dodendreae in a morphological, not in a physiological sense, being intendednbsp;to show the connection with a periderm. We are innbsp;fact vividly reminded of the formation of periderm,nbsp;which we observed in Lepidodendreae.

Of the group of Leiodermariae we are acquainted through Renault�s� labours with the structure of Sigillaria spinulosa, of which a good manynbsp;specimens have been obtained at Autun. Rind andnbsp;wood are there usually found separate from onenbsp;another, and the surface of the former is in mostnbsp;cases not preserved. The rind had been known fornbsp;some time, and had been named by Brongniart Dic-tyoxylon before the relation of the two remainsnbsp;to each other was cleared up by the help of somenbsp;fortunate discoveries, which showed them in actualnbsp;connection with one another and revealed at thenbsp;same time the characteristic features of the surface.nbsp;Here too there is a central cavity evidently oncenbsp;occupied by the pith; this cavity is surroundednbsp;as in Sigillaria Menardi by a number of vascularnbsp;strands, which are more or less circular in form and are succeeded on thenbsp;outside by a much thicker mass of secondary xylem. The bundles alsonbsp;which surround the pith are similar in structure to those of Sigillarianbsp;Menardi, but they have not their regularity of form; they vary greatlynbsp;in breadth and several of them are often attached laterally to one another.nbsp;To put the matter briefly, we cannot dismiss the impression that we have tonbsp;do in this case with a circular tracheal zone, which through unequal development has been broken up into many separate fragments having naturallynbsp;therefore the form of strands. This is not so distinctly shown in Renault�s ^

drawings, especially not in those that are less highly magnified. His sections may have too regularly avoided this zone. P'or this reason Inbsp;give here a sketch of the central portion of a stem which was determinednbsp;by Renault himself and given by him to Williamson, who most kindly lent itnbsp;to me for the purpose of this drawing. I remark at the same time that thenbsp;specimens preserved in the Paris Museum are perhaps less irregular, butnbsp;have essentially the same character, and of this I have satisfied myself bynbsp;repeated examination. This is so far important as tending to make us lessnbsp;inclined to the assumption of a pith surrounded by distinct bundles thannbsp;to the view that the wholenbsp;together is a central bundle-strand, the centre of which isnbsp;parenchymatous, while portionsnbsp;of the periphery are tracheal innbsp;character to an extent notnbsp;exactly defined. And since, asnbsp;we know, the smallest narrowest elements lie on the outside,nbsp;the result would be a picturenbsp;similar to that which would benbsp;produced for example in Le-pidodendron Harcourtii, if itsnbsp;tracheal ring were broken upnbsp;into separate portions, as isnbsp;actually the case in L. Jutieri.

And if this is the natural conception as regards one species of the genus, we are further drivennbsp;to adopt the same explanationnbsp;of the other species, Sigillarianbsp;Menardi, which differs only bynbsp;its greater regularity and morenbsp;perfect consolidation. We cannot enter further here intonbsp;the consequences which result from this view; we should quickly arrivenbsp;by this path at the general conception already adopted by some authors,nbsp;namely that pith and peripheral ring of vascular bundles have beennbsp;formed by differentiation from the originally simple central strand.nbsp;Van Tieghem�s^ view is determined by the opposite idea, for he wouldnbsp;everywhere explain the axile cauline bundles as due to the coalescencenbsp;of several trace-bundles with their wood-portions turned one towards

the other. He accordingly considers the central wood also of Lepi-dodendron to be composed of these leaf-traces. The secondary wood of Sigillaria spinulosa forms a firmly-closed ring of considerable thicknessnbsp;traversed by numerous rays of more than one kind, and has no specialnbsp;features ; there is one point only to be noticed, that its primary rays do notnbsp;always coincide on the inner boundary with the places where the trachealnbsp;ring of the central cylinder is interrupted, and that in this point also therenbsp;is less dependence of the two systems on one another in this species, thannbsp;appears to exist in Sigillaria Menardi. The inner cortical layer, consistingnbsp;of delicate tissue and inclosing the transverse sections of the ascendingnbsp;leaf-trace-bundles, is only rarely and imperfectly preserved ; the contiguousnbsp;layer on the outer side shows exquisite Dictyoxylon-structure throughoutnbsp;up to close beneath the surface; this is caused by the undulated plates ofnbsp;sclerenchyma approaching each other and uniting together here and there,nbsp;and then again separating from one another. This layer is also termednbsp;by Renault in his accustomed way the � couche sub�reuse.� How far it reallynbsp;belongs to the periderm I am unable to determine ; the question must benbsp;left to further investigation.

While the scarcity of the Sigillariae in the upper beds of the Carboniferous formation makes it easy to understand why well-preserved remains of them should be so rare in the French deposits, it is very surprising to find that they are equally rare in the English coal-fields, thoughnbsp;impressions of Rhytidolepis-forms are abundant enough, and even theirnbsp;outer rinds with the structure preserved cannot be said to be scarce. Onlynbsp;one specimen has been found up to the present time, as far as I know,nbsp;which shows the rind and the woody body in connection. This comes fromnbsp;Oldham and is in Carruthers�s possession. Since the well-preserved surfacenbsp;shows that it belongs to a species of the section Rhytidolepis, probablynbsp;Sigillaria Saullii, it is most desirable that it should speedily be submittednbsp;to the examination which has hitherto been deferred. Its owner, however,nbsp;has been kind enough to show me the rough specimen, and I can onlynbsp;confirm the statements of Williamson and Hartog The latter authorsnbsp;say: � The fragment has the continuous cylinder and all the internal organisation of Corda�s Diploxylon �; it has therefore a structure, which, if we disregard the secondary wood, answers perfectly to that of the central cylindernbsp;of Lepidodendron Harcourtii. This only confirms us in the view which hasnbsp;been already explained respecting the pith and the tracheal zone surrounding it in Sigillaria spinulosa and Sigillaria Menardi, and we shall benbsp;able perhaps to set this view in a still clearer light, when once the detailsnbsp;of the structure of this Sigillaria Saullii have been laid before us. Thenbsp;little that Williamson^ has said about Rhytidolepis concerns only the outer-

most cortical layer composed of stout parenchyma, the elements of which are directed inwards in rows; it is therefore of small importance. Whatnbsp;Dawson ^ has termed Sigillaria-structure is so imperfectly described by himnbsp;that we can arrive at no conclusion respecting it; as the stems in questionnbsp;showed the pith of Artisiae and vessels with bordered pits, it is natural tonbsp;suspect that they belonged to Cordaiteae.

To conclude�it will be necessary to submit the structure of the leaf-trace-bundles of Sigillaria Menardi and S. spinulosa to further and closer consideration, because Renault in his different publications has made it thenbsp;ground of some far-reaching conclusions. According to his figures^ eachnbsp;trace-strand behaves very differently in different parts of its course.nbsp;Tangential sections through the secondary wood present it in rathernbsp;oblique tranverse section. It is formed of two evidently separate trachealnbsp;groups, between which lie according to the text the spirally thickenednbsp;initial elements. This would evidently be the so-called diploxylous structure of Cordaiteae. Then in the inner rind the strand assumes muchnbsp;greater unity of character ; the transverse section� shows a quite compactnbsp;apparently homogeneous xylem-strand obtusely triangular in form, innbsp;which the spiral tracheides are said in the text to be centrally situated, anbsp;little nearer to the outer side. We do not learn from these sections, anynbsp;more than from those previously mentioned, whether the bundle is collateral or concentric. This appears for the first time in a figure in Renault^,nbsp;a tangential section through the Dictyoxylon-layer of the rind which hasnbsp;hit the emerging foliar bundle exactly transversely. The bundle is nownbsp;broader than before and its transverse section is crescent-shaped and nonbsp;longer triangular. Its upper inner segment (bois centrip�te) consists ofnbsp;tracheides lying together in no particular order. The lower outer (boisnbsp;centrifuge), which was very feebly developed in the previous section andnbsp;answered to the outwardly inclined apex of the triangular transversenbsp;section, is now considerably enlarged, and its tracheides arranged in rowsnbsp;have rays of parenchymatous tissue between them. Next to it the bast-layer is still to be seen in the form of an arch, and as it does not appearnbsp;elsewhere round the wood, it is evidence of the collateral character of thenbsp;bundle-strand. We are thus undoubtedly justified in comparing it withnbsp;the foliar bundle of Cycadeae mentioned above on p. 106 in the chapternbsp;on Cordaitae. Reference may also be made to former remarks on Myelop-teris, but Lepidodendreae must for the present be left out of consideration,nbsp;since observation has led to no direct conclusions in their case, and we arenbsp;first led to suspect collateral structure in the strand by considerations connected with the behaviour of the Stigmariae which we have yet to consider.

The peculiar structure of the trace-bundle of Cycadeae has been well explained by Mettenius�^, who was the first to notice the distinction betweennbsp;the centripetal and centrifugal portions of the xylem, between whichnbsp;lies the initial strand, and the terminology of the French authors maynbsp;therefore be traced directly to him. But at the same time the terms whichnbsp;they employ are unfortunately chosen, since they may mislead the readernbsp;into regarding the two parts of the bundle as anatomical members essentiallynbsp;distinct from and entirely independent of one another. Mettenius wasnbsp;perfectly aware that this is not the case; he is careful to show how thenbsp;initial strand, so placed in the inner angle of the leaf-trace in the segmentnbsp;of the stem that there is only � bois centrifuge � present, gradually movesnbsp;towards the outside while the bundle is still young, till it has reached thenbsp;central position characteristic of the leaf-segment. It is true that twonbsp;woody portions now appear on the single transverse section, but they are innbsp;no respect essentially different from one another; they are connected laterallynbsp;below, and together they form the one xylem-strand of the bundle, in whichnbsp;the displacement of the initial group has simply given rise to an unimportantnbsp;alteration. It appears to me therefore that the French anatomists, vannbsp;Tieghem and his school, have not rightly understood Mettenius, when theynbsp;oppose the two parts to one another as � bois centrip�te � and � bois centrifuge,� and regard them as distinctly diffei'ent things. Thus we find vannbsp;Tieghem ^ saying unreservedly : � This second portion of the wood (centrifugal) corresponds to the normal wood of the cauline bundle ; it is the fannbsp;formed by the centripetal wood which is the superadded portion.� This isnbsp;not correct; it is the two parts together which correspond to the � boisnbsp;normal,� and nothing beside is added to it, only the initial point of thenbsp;ultimate development has suffered displacement. And this fundamentalnbsp;error appears in other authors in a more advanced and more pronounced form.nbsp;Thus Bertrand and Renault� have written quite recently; � The caulinenbsp;bundle preserves its structure when it enters the leaf, only its primary woodnbsp;is reduced and a new tissue, the centripetal wood, is intercalated betweennbsp;its pole and its anterior face. The centripetal wood of a unipolar diploxy-lous bundle is therefore not the homologue of the displaced primary wood ofnbsp;the normal unipolar bundles. The tissue is a relic of a former organisation.�nbsp;There is scarcely a word in this sentence to which I am not obliged tonbsp;take exception. Mettenius� figures themselves teach the exact contrary,nbsp;but I have also satisfied myself perfectly by personal examination of variousnbsp;young individuals of the group of Cycadeae that the actual state of thingsnbsp;is as I have here portrayed it. Had Mettenius adopted a different ter-

� Mettenius, G., Beitrage zur Anatomie der Cycadeen in Abh. d. kgl. sachs. Ges. d. Wiss. Bd. vn (Math. Natw. Cl. vol. v), Leipzig, 1861.nbsp;nbsp;nbsp;nbsp;^ van Tieghem. Trait� de bot. i88^, p. 812.

minology, had he called for instance the leaf-strand of Cycadeae mesarch, and that of Iso�tes exarch in opposition to the normal form, we mightnbsp;perhaps have been spared this misconception. It is evident from what hasnbsp;been said above that to employ the current phraseology and speak of anbsp;diploxylous bundle has no meaning, except when we are dealing withnbsp;a certainly collateral trace-strand. For this reason I have been able tonbsp;employ the word without hesitation when speaking of Cordaiteae, and itnbsp;may also be used here for the leaf-trace which passes through the cortex ofnbsp;Sigillariae. But we must think twice before we go beyond this, and say withnbsp;van Tieghem^: �this double wood is also found in the leaves of Sigillariae,nbsp;but here we are going back to the rule, for the stem too has a double wood,nbsp;the interior primary and centripetal, the exterior secondary and centrifugal.�nbsp;It is true that this is also going back to Mettenius^, but he only knewnbsp;Sigillaria from Brongniart�s description. The objection is that in this modenbsp;of conceiving the matter a sufficiently sharp distinction is not drawn betweennbsp;primary wood and secondary additional growth. If the latter supervenes,nbsp;it certainl}'' unites immediately with the outer portion of the xylem. Butnbsp;whether in a given stem of the species in question having secondary growthnbsp;the original structure of the primary bundle followed the type of Iso�tes ornbsp;that of Cycadeae cannot be determined, unless we are in a position to studynbsp;the history of the development of the specimen. Van Tieghem appears tonbsp;underrate the importance of this distinction, or else he could not possibly saynbsp;� The leaf of Sigillariae derives its ligneous elements at once from the anglesnbsp;of the primary wood and from the inner margin of the superposed secondarynbsp;wood� ; for this leaves it uncertain whether the latter elements connect withnbsp;the outer strand of the primary wood or with that of the secondary, ornbsp;partly with the one and partly with the other. Moreover the abovenbsp;sentence determines a priori the extremely doubtful question of thenbsp;anatomy of Sigillariae, for it assumes the presence of a medullary cylindernbsp;surrounded by isolated leaf-trace-strands. And yet we have seen hownbsp;strongly the stages in the differentiation of the primary structure pointnbsp;to the conception, that the central parenchyma with the surrounding ringnbsp;of bundles is a single central strand partly developed in the form ofnbsp;parenchyma, after the analogy of Lepidodendron Harcourtii. The strandnbsp;Would in that case be concentric in structure and could not come intonbsp;consideration here; the diploxylous leaf-traces would be attached to itsnbsp;periphery. Van Tieghem it is true would not consider this an importantnbsp;distinction, for he considers every central strand of the kind to be formed bynbsp;the coalescence of collateral leaf-traces, as was observed above on p. 253-To discuss in detail the mutual relations of the two distinct types which

� van Tieghem, Trait� de bot. 1884, p. 812. van Tieghem, Trait� de bot. 1884, p. 1307.

have here to be brought into comparison, that of Gymnosperms on the one hand and that of Lycopodiae and Lepidodendrae on the other,nbsp;would require a lengthy inquiry into the elementary anatomical ideas ofnbsp;French and German authors. This would carry us too far from our immediate subject, and the intimations already given will be sufficient for thenbsp;botanist. An inquiry into the comparative anatomy with special referencenbsp;to this point might possibly bear good fruit; it might perhaps bring us nearernbsp;to the understanding of the mode in which the existing types of structurenbsp;in stem and root have been developed from a common initial form.

We cannot leave the consideration of the leaf-trace without a brief notice of the two small lateral scars, which like a pair of brackets inclose thenbsp;place of fracture of the vascular bundle in Sigillariae, and which werenbsp;observed in similar form on the scar of Lepidodendrae. Renault ^ has shownnbsp;in the case of Sigillaria spinulosa that they are not remains of vascularnbsp;bundles, but are simply parenchymatous, and Stur�s^ statement, who refersnbsp;them to the division of the foliar bundle in the cortex, must be correctednbsp;accordingly. On other points Renault�s account does not supply us withnbsp;much certain information with respect to these objects. He usually termsnbsp;them � lacunes,� and says that they are gaps on the two sides of the vascularnbsp;bundle; in the preface^, which is directed against Williamson, he says:

� the two lateral lacunae answer to gum-canals.� But the statement in the same place ^ that these canals pass through the entire thickness of thenbsp;rind, does not properly agree with his own drawings, in which they by nonbsp;means appear everywhere close to the vascular bundle ; they may possiblynbsp;have been at an unusual distance from it and could not be included in thenbsp;drawing. This will be seen by comparing his figures ^; and other figuresnbsp;in which they certainly appear, show them in such variety of form that it isnbsp;hopeless to think of forming a clear idea of their character. In any case wenbsp;cannot regard it as proved, that they represent or inclose gum-passages.

Renault � gives some transverse sections of leaves of Sigillariae, which show a single very broad diploxylous vascular bundle. It is quite possiblenbsp;that these remains really belong to Sigillaidae, but it is certainly not yetnbsp;proved, as Renault* himself admits when he says, �which I think may benbsp;referred to Sigillariae on account of their outward form,� amp;c.

As regards the affinities of Sigillariae, now that the ideas of older authors, who like Corda, for example, compared them with Cacteae andnbsp;Euphorbiae, have been definitively set aside, there remain only two opposingnbsp;views, one of which was founded by Brongniart and places them withnbsp;Cycadeae, while the other is maintained by Goldenberg, Schimper, and the

� Renault (8). nbsp;nbsp;nbsp;� Stur (5), p. 293.nbsp;nbsp;nbsp;nbsp;Renault (2), vol. iii, p. 4.nbsp;nbsp;nbsp;nbsp;* Renault (2),

vol. iii, p. 5. nbsp;nbsp;nbsp;Renault (1), t. 12, f. i and 8, t. 3, f. 17, t. 5, f. 32.nbsp;nbsp;nbsp;nbsp;� Renault (8), t. 3, f. 18,

t- 5. t- 31� t- 6, f. .33. nbsp;nbsp;nbsp;^ Renault (1), t. 12, ff. 6-9.nbsp;nbsp;nbsp;nbsp;* Renault (1), p. 265.

English authors, Williamson especially, and brings them Into close relations with Lepidodendrae, and through them with Archegoniatae. This divergencenbsp;of opinion has very recently given occasion to a controversy between Renaultnbsp;and Williamson, which has been already noticed more than once, and whichnbsp;has been conducted by the tv/o opponents in several of the publicationsnbsp;cited above. One of the chief arguments advanced by Renault, and drawnnbsp;from the growth in thickness of the stem, which is supposed not to occur innbsp;Archegoniatae, has already been sufficiently examined in the chapter on Lepidodendrae. He finds a second and fundamental difference, which ought tonbsp;prevent any approximation of Sigillariae and Lepidodendrae, in the structurenbsp;of the leaf-trace-bundles. These are diploxylous in Sigillariae, and suchnbsp;bundles do not occur in Archegoniatae; Sigillariae therefore cannot belongnbsp;to Archegoniatae, while Lepidodendrae being Archegoniatae have monoxy-lous bundles. This argument, which is quite analogous in character withnbsp;the argument from growth in thickness, I must also consider to be inconclusive, for we have in Iso�tes an Archegoniate plant with anomalousnbsp;position of the initial strand, and there is no apparent reason why therenbsp;should not have been more of them. Renault himself places Myelopterisnbsp;among Ferns, notwithstanding that it exhibits the like anomaly. Moreover,nbsp;as has been already said, we are not yet certain whether the structure of thenbsp;leaf-trace in Lepidodendrae was collateral or concentric. I incline myself,nbsp;as I have said, to the view that it was collateral, not only because innbsp;Lepidodendron Harcourtii we find a group of bast-fibres in front of onenbsp;side only, the outer side, of the transverse section of the bundle, but chieflynbsp;on account of the character of the traces in Stigmariae, of which we shallnbsp;have to speak at greater length in the next chapter. But if the bundle innbsp;Lepidodendron is collateral, then it is also immediately diploxylous, ifnbsp;Renault is right in his view with regard to the position of its initial group,nbsp;and every essential difference in this respect between the two groups falls tonbsp;the ground. If on the other hand it is concentric, then there is reallynbsp;a difference between them, and the only question is as to the importance ofnbsp;this difference; but on this point there can be no dispute. Lastly, as regardsnbsp;the separate bundle-strands which surround the pith in Sigillaria, theirnbsp;relations to the annular border of tracheides in the central strand of Lepidodendron Harcourtii have already been sufficiently considered; and thenbsp;like character appears to be found also in one type of. Lepidodendron,nbsp;L. Jutieri, Ren., as is justly and strongly urged by Williamson'. It is truenbsp;that a careful examination of this specimen, which may possibly correspondnbsp;with Sigillaria Menardi or S. spinulosa before the formation of secondarynbsp;wood, is much to be desired. When I thus weigh in my own mind all thenbsp;arguments and counter arguments, and take also into consideration the

question of Stigmariae, whicti cannot be treated here, but must form the subject of the next chapter, I arrive at the result that it is impossiblenbsp;to obtain incontestable proof of either of the two views from purelynbsp;anatomical sources, but that Williamson�s remains the more probable,nbsp;because the main argument in support of the contrary view is entirelynbsp;overthrown by the proof of the presence of secondary wood in Lepidoden-dron, which is undoubtedly one of the Archegoniatae.

It has long since been perceived that the most decisive proof in one or the other direction would be obtained by the discovery of fructifications ofnbsp;Sigillaria, but such a discovery exhibiting the fruit of Sigillaria in directnbsp;connection with undubitable scars of the plant long remained a piuninbsp;desiderium. Both sides appealed to cases in which the two parts werenbsp;supposed to occur together, but of these cases there was no sufficient proof.nbsp;Renault 1 acknowledging them to be conjectural has never used thenbsp;fructifications in support of his view, while those who maintain that thenbsp;group belongs to Gymnosperms, Dawson^ especially, look for them asnbsp;a rule among the numerous seeds of the Carboniferous formation, which wenbsp;have considered in connection with Cordaiteae. Certain spike-like fructifications, resembling those of Lepidodendrae, have been described by thenbsp;representatives of the other view under the name of Sigillariostrobus.nbsp;Goldenberg� especially has figured a number of remains of cones in a verynbsp;crushed condition, which he ascribes without apparent reason to Sigillariae,nbsp;and in which groups of macrospores lie between flat leaves with a broadnbsp;base. Single detached leaves showed a small heap of similar spores atnbsp;their base on the inner side ; the wall of the sporangium which containednbsp;them could not be seen. The three edges of the pyramid were distinctlynbsp;shown in the single spores. O. Feistmantel^ also has figured variousnbsp;Sigillariostrobi which had been previously described in different publications, and has drawn up a complete list of the literature. These remainsnbsp;of cones, in other respects apparently in no very good state of preservation,nbsp;are said to have short obtuse sporangial leaves, on the inner side of whichnbsp;were laid numerous macrospores. As there is no proof that they belongednbsp;to Sigillaria, they have but small importance for us, and it will be sufficientnbsp;to refer the reader for further details concerning them to the originalnbsp;literature.

The question being in the position which has been now described, it can be understood that Zeiiler�s� latest discovery of cones with longnbsp;stalks showing the character of the axes of Sigillaria is of the greatestnbsp;importance. These cones, several in number, come from the mine L�Escapelle,nbsp;in the coal-field of the department of the Nord, and are preserved in the

1 Renault (2), vol. i, p. 151, and vol. iii, p. 8. nbsp;nbsp;nbsp;� Dawson (8).

form of impressions with an outer crust of coal. Through the kindness of their discoverer I have had the opportunity of inspecting them carefully,nbsp;and I have thereby fully satisfied myself of the con-ectness of his statements.nbsp;But I would observe at the same time that the specimens require to benbsp;examined with extreme care and in various lights, and that the detailsnbsp;of the organisation are by no means so apparent on the dull black rind ofnbsp;coal as on the tables appended to the memoir. The cones are described asnbsp;different species of Sigillariostrobus, and the one which shows strict proof ofnbsp;Sigillaria-nature is named Sigillariostrobus Tieghemik The specimen consistsnbsp;of the lower portion of the cone placed on a tolerably long stalk surroundednbsp;by linear leaves. The rows of scars on the stalk allow of an approximatenbsp;determination of the plant as Sigillaria scutellata, Brongn., or S. periploca,nbsp;Boulay, a species which is particularly abundant in the seam from which thenbsp;cones come. The leaves which bear sporangia all stand out from the stem,nbsp;the macrospores lie on their cushions which are narrowed into the shape of anbsp;wedge, and the lamina is broadly lanceolate, pointed and one-nerved. Therenbsp;is really therefore a perfect resemblance to Goldenberg�s Sigillariostrobus,nbsp;which was only a little smaller. In the other and similar species also, whichnbsp;occurred in the form of large fragments from different parts of the cone,nbsp;Zeiller could find only the same kind of macrospores. He considers thenbsp;possibility^, which in fact there really is, that these Sigillaria-cones maynbsp;have been isosporous, though the considerable size of the spores is notnbsp;in favour of this, and he also raises the question whether the two forms ofnbsp;spores might not have been produced on different cones, in which case thenbsp;Cones that contained the microspores could not be recognised as such whennbsp;preserved in coal. In fact on one of his cones (Sigillariostrobus nobilis�) therenbsp;was no trace of a spore to be seen. Renault ^ has just published a preliminarynbsp;communication on a spike-like fructification which he classes with Clathrarianbsp;or Leiodermaria, but without stating his reasons. He says : �The generalnbsp;appearance of this spike, its dimensions, the form and length of the bracts,nbsp;their disposition in close spirals and the diameter of the axis bring itnbsp;very near to, if they do not identify it with, the spikes which are often metnbsp;with among the leaves at the extremity of the stem of Sigillaria Brardii.�nbsp;That is all. It is stated that pollen-sacs in large numbers were attachednbsp;on the under side of the horizontal basal portion of the spike on bothnbsp;sides of the median nerve, and that orange-yellow pollen-grains of ellipticnbsp;outline were to be obtained from them. I was unfortunately unable tonbsp;see the specimen, which was just then being engraved, and a drawing ofnbsp;It did not give me all the information which I required.

XII.

The Stigmariae are some of the best-known and commonest of fossil forms, and are constantly to be found on every refuse-heap in a coal-mine.nbsp;They occur sometimes as cylindrical casts of greater or less thickness besetnbsp;with peculiar regularly disposed scars, sometimes as impressions in whichnbsp;long finger-like appendages with blunt terminations are attached to thenbsp;scars. The distribution of these remains through the series of formationsnbsp;agrees very nearly with that of Lepidodendreae. Most abundant in thenbsp;Coal-measures they are still frequent in the Carboniferous Limestone, andnbsp;may be traced backwards into the Devonian formation. Dawson^ hasnbsp;figured remains from St. John in New Brunswick and from Gasp�, of whichnbsp;Stigmaria perlata ^ at least may be regarded as certainly belonging to thisnbsp;group. They are found in the other direction as high as the Rothliegende,nbsp;in which, as we see, the last undoubted Sigillariae occur, at Autun fornbsp;example, and also according to Weiss� near Schmalkald in Thuringia andnbsp;near Zorge in the Harz. Above this point they disappear entirely. Thenbsp;most complete collection of the older literature on Stigmaria is to be foundnbsp;in G�ppert¹ and Weiss�; for the newer the reader may be referred tonbsp;Renault � and to Williamson�s last publication.

The common species, which is generally distributed through the strata from the Limestone below to the upper beds of the Carboniferous formation,nbsp;is Stigmaria ficoides, Brongn.; and closely connected with it are a numbernbsp;of other forms which will be briefly noticed presently, and which are treatednbsp;by most authors, by G�ppert also and Schimper as mere varieties, thoughnbsp;some at least of them differ greatly from it in habit. The casts of Stigmarianbsp;ficoides, usually merely cylindrical fragments, are not unfrequently of considerable length. Hooker� mentions some that were twenty metres,nbsp;G�ppert one that was thirty metres in length. Their branching is alwaysnbsp;dichotomous, and the two arms of the bifurcation pursue a parallel course

* Weiss (1), p. 171. nbsp;nbsp;nbsp;� Renault (2), vol. ii, p. 152. �� gt;----------

' Schimper (1). nbsp;nbsp;nbsp;� Hooker (4), p. 432.nbsp;nbsp;nbsp;nbsp;G�ppert (3), p. 188,

rinds, distinctly marked cicatrices and the structure above described, are phanerogamous gymnospermous plants near modern Cycads,� we cannbsp;scarcely think his statement justified, when we consider that we do notnbsp;even' know whether the specimen on which he founds this conclusionnbsp;really belongs to Sigillariae. But since he acknowledges, though notnbsp;without reserve, the correctness of Zeiller�s observations, he arrives ultimately at the following conclusion: � The Sigillariae, an essentially transitional group of plants, would therefore separate into Leiodermarieae ornbsp;phanerogamous Sigillariae with smooth rind near Cycadeae, and intonbsp;Rhytidolepis or cryptogamous Sigillariae with fluted rind allied to Iso�tes.�nbsp;But this sentence is simply a petitio principii, for it is not easy to seenbsp;why we should separate the ribbed Sigillariae from the others, so longnbsp;as there are no reasons which compel us to do so. And now that we arenbsp;acquainted with an archegoniate fructification in the one group, we mustnbsp;with Williamson and Zeiller assume the existence of a similar fructificationnbsp;in the other group till proof to the contrary is produced. No doubt thenbsp;question of transition groups may have to be considered here, but it mustnbsp;first be shown that there were such groups. And so till Renault can provenbsp;his view, I shall from the facts which lie before us hold fast on the whole tonbsp;the opinion that the Sigillariae were of the nature of Archegoniatae.

from the beginning. Their surface is smooth or slightly uneven, and is furnished with shallow pits containing the fracture-scars of the appendages; these are in loose order and show regular quincuncial arrangement. Thenbsp;positional relations which are at the foundation of this arrangement havenbsp;not yet, as far as I know, been accurately determined. The outline of thenbsp;Stigmariae is circular, and the boundary-line of their circumference is sharplynbsp;defined ; in the centre is a second circle, the central point of which is a dotlike protuberance. Good figures are supplied by Schimper^, Heer andnbsp;Goldenberg

The appendages are found in unusual abundance in immediate connection with the axes; where these occur as impressions in coal, the appendages are scarcely ever wanting, and they spread out on the two sidesnbsp;forming a right-angle with the axis. And when the rock is examined in

which the casts of the axes lie, every surface of divisionnbsp;in it is seen to be traversednbsp;by the appendages, whichnbsp;spread like rays on all sidesnbsp;from its transverse fractures. Where they lie freenbsp;their whole length through,nbsp;they appear as cylindricalnbsp;or dactyliform bodies flatlynbsp;rounded at the upper extremity and suddenly contracted at the base, and having a smooth surface.nbsp;If they are pressed flat, as is always the case in impressions, the originalnbsp;cylindrical form can usually be concluded from the longitudinal folds. Thenbsp;finest specimens are those which are obtained by skilful use of the hammernbsp;from the English calcareous nodules. These facts have all been given bynbsp;Steinhauer^ in his excellent account of Stigmaria. Really good figuresnbsp;(Fig. 30) are only rarely to be met with in the literature. Lindley andnbsp;Hutton�, Corda�, Sternberg'^, and Zeiller� may be consulted. The fossilnbsp;is in fact so common that mo.st authors have not thought it necessary tonbsp;give an illustrative figure. Sometimes, but not very often, the appendagesnbsp;are dichotomously divided, and in that case each branch has its extremitynbsp;flatly rounded off in the usual manner. Goldenberg� and Corda^� havenbsp;given figures of such cases. Goldenberg found an ovoid body in the bifurcation ; a similar body marked with a longitudinal furrow is represented on

Steinhauer (1). nbsp;nbsp;nbsp;� Lindley and Hutton (1), vol. i, tt. 32, 33, 36.

Corda�s fine specimen on the upper extremity of a simple appendage. In other specimens, according to Goldenberg^ and G�ppert^, there is atnbsp;least a small circular scar in the angle of bifurcation, which Goldenbergnbsp;supposes to be the point of attachment of the ovoid body. But the last-named forms, not being attached to the axes, are not above suspicion.nbsp;Though Goldenberg and Corda consider these ovoid bodies to be fructifications of Stigmariae, it seems to me that there is as yet no sufficient groundnbsp;for this view, and I must consider any determination of them at present tonbsp;be premature.

From this notice of the appendages we must return once more to the axes, and take note of some states of preservation which demand carefulnbsp;consideration. The first to be noticed are the internal casts mentionednbsp;above on p. 8. It very often happens that we find inclosed in thenbsp;Stigmaria a cylindrical cast of small diameter, which being sharplynbsp;separated from the surrounding mass is plainly distinguishable on everynbsp;transverse fracture, and may by splitting the stone be laid bare sometimesnbsp;for a considerable distance. That we are here concerned with an integralnbsp;part of the plant, and not with some other remains introduced with thenbsp;fossilising material, is shown by the great prevalence of the phenomenonnbsp;and the regularity with which it is observed, if attention is directed to it.nbsp;It is only in Stigmariae that these internal cylinders are found, or if something analogous is met with here and there in Lepidodendron, it is of rarenbsp;and exceptional occurrence. The possible reason for this better state ofnbsp;preservation in Stigmariae will be considered further on. In pieces favourably split through, such as are found occasionally in coal-refuse and innbsp;particularly good condition in the hard sandstone of the Culm of Burbachnbsp;near Thann, the surface of the interior cast is seen to be marked with somewhat crowded fusiform areolas, which thrust their extremities in betweennbsp;one another and are separated by a lattice-work of narrow bars. In thenbsp;specimens from Burbach this network is generally very clearly shown bynbsp;its dark brown colour. If the remains are preserved in fine grayish blacknbsp;clay-slate, there is then no difference of colour, and the lattice-structure isnbsp;generally less distinct, though in this case it becomes njore apparent if thenbsp;areolae are somewhat convex and raised above the surface, and the barsnbsp;look like furrows lying between them. I have myself repeatedly foundnbsp;instructive specimens of this kind at Saarbriicken. There can then be nonbsp;doubt, as was said above on p. 8, that this interior cylinder is the cast ofnbsp;the central cylinder surrounded by the ring of wood. The inner surface ofnbsp;the ring of wood necessarily left its impression on the cast, and the markingsnbsp;on the cast correspond with that impression. When the cast was fullynbsp;formed, the ring of wood entirely or almost entirely disappeared. The outer

cast which encloses the other has taken the place of the peripheral portions of the axis of the Stigmaria. This mode of explanation, which was suggested long ago by Steinhauer and has been accepted by all authors, isnbsp;in agreement with the fact that the interior cylinder is never found in anbsp;central position, but lies excentrically almost touching the surface of thenbsp;surrounding cast on one side, and that when the entire axis is sunk in andnbsp;pressed flat, the cylinder is always in the middle of the one broad side of it,nbsp;having reached that position by its own weight. The Stigmaria-casts arenbsp;very often firmly connected by a narrow strip of substance on one side tonbsp;the rock in which they are imbedded, and then they do not fall out of theirnbsp;cylindrical mould. In such cases the cylinder of cortical tissue must havenbsp;been split longitudinally when the mould was filled, and through this fissurenbsp;the cast was brought into direct communication with the surrounding matrix ;nbsp;displacements also were usually produced and longitudinal foldings of thenbsp;surface, and these serve as characteristic marks. From specimens of thisnbsp;kind, either through the operation of running water or if they were split bynbsp;pressure, the interior cylinder might obviously slip out on one side, and it isnbsp;sometimes found free in the rock. This happens occasionally in the Culm ofnbsp;Burbach. I have a specimen of the kind myself twelve centimetres in length,nbsp;in which the characteristic features of the surface are most distinctly to benbsp;seen. Good figures of such casts are given in Williamson^ and in Schimper�.nbsp;Further indications of original structure are occasionally observed in thenbsp;substance of the casts, but we must defer any notice of these till we come tonbsp;speak of the anatomical structure.

Hooker described in 1848 two small fragments of Stigmaria from the English Coal-measures, which are distinguished by the particularly sharpnbsp;preservation of the surface and depart in essential points from thenbsp;ordinary character. These specimens are not round casts, but irregularnbsp;fragments with scars on one side only. The scars, which ordinarily lie innbsp;slight depressions, here occupy the apex of flat protuberances. In each ofnbsp;these protuberances is sunk a smooth-walled crater-like cavity rathernbsp;broader below, which penetrates to a depth of six millimetres and resemblesnbsp;the canal of a boring animal. The exterior margin of the orifice is slightlynbsp;raised and thickened. From the bottom of each pit rises a conical bodynbsp;nearly filling the pit, which narrows a little towards the upper part, andnbsp;being broken off transversely exactly at the orifice, shows on the surface ofnbsp;fracture a slightly depressed central trace-point. According to Hookernbsp;these cones are the basal portions of the appendages, the projecting portionnbsp;having been broken off above the depression. The different appearance ofnbsp;the ordinary specimens before described is referred by him to the deforma-

tion caused by pressure, to which the bases of the pits containing the appendages were exposed. All authors, as far as I know, have eithernbsp;silently or expressly accepted this explanation, though the circumstancenbsp;that such deep holes should have so entirely disappeared, always presentednbsp;some difficulty, especially in cases where from the perfectly regularnbsp;cylindrical form of the whole body the pressure, to which the surface mustnbsp;have been exposed, is not quite obvious. That this view is erroneous hasnbsp;been quite recently shown for the first time by Williamson \ who hasnbsp;proved his point unanswerably. He has brought together a long series ofnbsp;instructive specimens, some of which have been figured From these wenbsp;learn that we are dealing here not with the surface of the cast, but withnbsp;fragments of a peculiar mould. It will be shown more fully later on thatnbsp;there was a broad tubular cavity present innbsp;every appendage. Supposing then that thesenbsp;appendages were destroyed and torn awaynbsp;down to the preserved basaT portion in anbsp;specimen which was going to be covered up,nbsp;the latter will have been beset with thesenbsp;basal portions, as with so many open cups;nbsp;and at the bottom of each of these therenbsp;must have been a short thread-like process,nbsp;the remains of the single vascular bundlenbsp;which has been torn away. Then when thenbsp;object has been buried and the substance ofnbsp;these cups has been changed into coal or hasnbsp;entirely disappeared, if cast and mould arenbsp;separated from one another, every depressionnbsp;will appear on the latter as a flat protuberance,nbsp;and the wall of every cup as an annular fissurenbsp;entering deeply into the mould. But the cone in the pit answers tonbsp;the cast which must be formed in the cavity of the cup, and necessarilynbsp;comes to an end at the point of insertion of the appendage, whichnbsp;here corresponds to the margin of the orifice of the annular fissure.nbsp;The remains of the vascular bundle which appears at this spot must leavenbsp;behind it the central dot-like impression. As has been said, no doubt cannbsp;ever arise with regard to this explanation. The mould figured bynbsp;Williamson ^ should be compared with the diagrammatic representationnbsp;given here in Fig. 31. Williamson has also obtained analogous resultsnbsp;artificially from casts of suitable Stigmariae. On the occasion of my lastnbsp;visit to Manchester I had opportunity through his kindness of examining

Williamson (6)* nbsp;nbsp;nbsp;^ Williamson (6), tt. I3 and 14.nbsp;nbsp;nbsp;nbsp;^ Williamson (6), t. 14.

for myself his entire series of specimens, and in the Museum at York I saw another highly instructive specimen, which may be briefly noticed in thisnbsp;place. On one side of the block of stone is the mould of the axis of anbsp;Stigmaria which has been split nearly through the middle, and in it appearnbsp;the bases of the appendages in the form of round holes. The cavitiesnbsp;corresponding to the appendages run like long tubes through the entirenbsp;piece of stone, showing the original rounded form. In each of these tubesnbsp;is a cast of compact, crystalline, milkwhite limestone, which does not however touch the wall, and may therefore be shaken to and fro in its bed. Ofnbsp;course only the basal surface of the cast can be seen filling the orifice ofnbsp;the tubes. On the sides of the block where portions of the stone havenbsp;been removed, a number of the tubes have been broken off, and the limestone cylinders have fallen out. In this case also the space between thenbsp;imbedding mass and the cylinder is due to the disappearance of the corticalnbsp;substance which originally lay between them.

There can be no doubt that the axes of Stigmariae became elongated by apical growth. Unfortunately it is only in comparatively few cases thatnbsp;it has been possible to examine their terminations with precision. Theynbsp;occur according to the statements of authors in two different forms. Innbsp;the one case the casts become slightly and suddenly smaller towards thenbsp;top and end in a blunt dome-like termination. An example of this is seennbsp;in Goldenberg�s^ Stigmaria rimosa, in which the scars gradually diminish innbsp;size as they approach the apex, and in Stigmaria ficoides figured in thenbsp;same place as Stigmaria Anabathra, where the size of the scars remainsnbsp;the same throughout; von Kohl�s^ specimen, though deformed and lessnbsp;valuable, must also be mentioned here, and a similar dome-like terminationnbsp;has been previously described by Steinhauer The appendages of coursenbsp;are not preserved in all these specimens. In other cases the extremities ofnbsp;the axes are of very much smaller size; Williamson has shown me transversenbsp;sections of not more than eight millimetres in diameter, which undoubtedlynbsp;belong to a Stigmaria, and he has figured a preparation of this kind I havenbsp;myself found on the refuse-heap of the Gegenort mine at Dudweiler nearnbsp;Saarbriicken a large and still undescribed block, on which I see the extremities of three Stigmaria-axes lying close together in the mould. Theynbsp;diminish rapidly in size and are at last scarcely five millimetres in breadth.nbsp;Two of them on the outermost margin of the block, the product of a dichotomy, appear to be united to one another, but I cannot affirm this withnbsp;perfect certainty on account of the unfavourable direction of the edge of thenbsp;fracture. But one of them bifurcates a little below the apex, and the twonbsp;slightly diverging branches reach a length of about three centimetres, one

being about twenty millimetres in diameter at the base, the other about fourteen. This specimen is particularly important and interesting, becausenbsp;the appendages appear in tolerably good preservation on both sides of thenbsp;terminations of its axes. They grow successively smaller and shorter as theynbsp;approach the terminations, and the distances between them diminish. Theynbsp;also become curved in the forward direction and close together bud-likenbsp;round the apex. Hence it is only as they develope that they acquire theirnbsp;definitive position at right angles to the axis, resembling in this respectnbsp;foliage-leaves. At the same time their regular progressive increase in sizenbsp;on both sides of every bifurcation proves that the division is not apparentnbsp;merely, a mere separation of the parts by crushing, and also that the linenbsp;of fracture was not essentially oblique. Otherwise there could not possiblynbsp;be this uniform decrease in size; appendages of equal length to thosenbsp;adjoining them would be found at the very apex. One figure only of anbsp;mould of this kind is known to me from the literature, and this is to benbsp;found in G�ppert and has been reproduced by him several times. Thenbsp;specimen is diagrammatically represented ; the appendages are all developednbsp;alike and spring also from the apex, and there is therefore reason to suspectnbsp;that the line of fracture passed obliquely near the apex, and is therefore ofnbsp;no value. The original specimen must be examined anew, and I do not atnbsp;present venture to speak decidedly about it. It would in any case be verynbsp;desirable to obtain fresh specimens, and these will certainly be found without difficulty, if they are searched for, on the refuse-heaps.

Before we proceed to consider the anatomy of Stigmaria, we may say a few words respecting the various forms which have been described innbsp;connection with Stigmaria ficoides, Brongn. One of the best characterisednbsp;of these forms is no doubt Stigmaria stellata which is known as a castnbsp;and also as a mould with appendages of the usual character attached. Eachnbsp;of its superficial scars is surrounded by short flat radiating furrows. Thisnbsp;form seems to be particularly abundant in the coal-district of Waldenburg.nbsp;In other places it is entirely wanting or is of very rare occurrence, as fornbsp;example in Lancashire, in Scotland, and in Canada. It is mentioned bynbsp;Hawson � from both the latter countries. Another form to be noticed isnbsp;Stigmaria conferta^, in which the scars are rather close to one another,nbsp;being separated only by narrow portions of the surface, for which reasonnbsp;the systems of parastichies are very distinctly shown. This form, whichnbsp;may possibly not really belong to the group, is rare like the last, havingnbsp;been found apparently up to the present time only in the neighbourhood ofnbsp;Radnitz and Svina in Bohemia. Stigmaria rimosa�, named Stigmaria

* G�ppert (1), Lief, i and 2, t. 9, f 6. Eichwald (1), vol. i, t. 15, f 2 ; G�ppert (1), Lief i and 2, t. 10, f. 12 ; Williamson (6), t. 13.nbsp;nbsp;nbsp;nbsp;^ Dawson (11), p. 69.nbsp;nbsp;nbsp;nbsp;� Corda (1), t. 13, f 9,

abbreviata on Goldenberg�s plate, comes from Hirschbach near Saarbr�cken, and has numerous strong longitudinal furrows on its surface running fromnbsp;one scar to another; the scars themselves lie in small pits, are broader in thenbsp;transverse direction, and have sharp lateral edges. This species bears somenbsp;resemblance to Sigillaria, and will have to be mentioned again later on.nbsp;Besides these marked forms there are some others which depart less widelynbsp;from the type of Stigmaria ficoides. We will mention here only Stigmarianbsp;ficoides var. undulata^ and Stigmaria ficoides var. sigillarioides^. In thenbsp;latter the scars are placed in longitudinal rows on vertical flatly-convex ribs,nbsp;and this gives it the habit of Sigillaria ; in the other form they are inclosednbsp;within sinuous furrows forming fusiform figures, which are connected together in the longitudinal direction by narrow bridges, and have each ofnbsp;them a central scar.

Numerous axes of Stigmariae with the structure preserved have been obtained from the calcareous nodules of the English and Rhenish Coal-measures, from the sphaerosiderites of Coalbrook dale, from the lenticularnbsp;calcareous stones of the Culm of Falkenberg in Silesia, and from the pebblesnbsp;of Autun. Similar fossils have also been found at Radnitz in Bohemia.nbsp;Their anatomy has been discussed by a great variety of authors, and hasnbsp;been illustrated by means of figures. The most eminent works on thenbsp;subject are those of Lindley and Hutton�, Corda^, Brongniart �, G�ppert�,nbsp;HookerWilliamson Binney�, and Renault^�. These specimens havenbsp;usually lost the rind and the appendages, and show only an annular woodynbsp;body of some thickness. The central portion of this body is almost alwaysnbsp;a hollow cylinder filled with a mass of stone showing no structure. This isnbsp;always the case, for example, in the specimens from Coalbrook dale, whichnbsp;are imbedded in a reddish-brown stone and show only the wood, but in a verynbsp;good state of preservation ; usually also in those from the calcareous nodules,nbsp;in which the crushed condition and displacement of the parts testify to thenbsp;soft state proper to the material when the object was being imbedded.

The transverse section shows this ring of wood broken up into a number of wedge-shaped segments, which are broader towards the outside,nbsp;and are separated from one another by primary rays or gaps passing throughnbsp;the wood. All the wedges come to an end abruptly, as if cut off, on the sidenbsp;towards the central tube, and show a flat bluntly-rounded termination, onnbsp;which no prominent primary bundle can be perceived. In other respects theynbsp;have no special peculiarity; they are traversed by numerous parenchymatousnbsp;secondary rays, and consist of scalariform ti'acheides, with broad lumina and

approximately quadratic transverse section, arranged in I'egular rows. But just on the innermost margin of the wedge this regularity is lost, and the elements, which have a much smaller transverse section, are no longer arrangednbsp;in rows. Here too the secondary rays come to an end, being separated fromnbsp;the inner margin of the wedge by a narrow tissue-layer, as is shown innbsp;Williamson�s figure In many, but by no means in all cases, a peculiarnbsp;disturbance of a different kind makes its appearance here and there innbsp;the wood much narrower elements in much more numerous radial rowsnbsp;being quite suddenly formed over larger or smaller segments of thenbsp;circumference. If this occurs on an extended scale and at one time, thenbsp;appearance may be that of the formation of an annual ring. If onnbsp;the contrary it is -confined within narrower limits, then it looks as ifnbsp;patches of a different character had been introduced into the otherwise uniform ring ofnbsp;wood.

The traces of the appendages, which have their origin on the inner margin of the wedges,nbsp;traverse the broad rays which separate thenbsp;wedges, and pass out into the rind As theirnbsp;course is at first ascending inside the ray,nbsp;then almost horizontal and curving outwards,nbsp;the transverse section meets them sometimesnbsp;in the transverse, sometimes in the longitudinal or even in the oblique direction.

Where they are cut through transversely, they always appear as long narrow wedges which are composed of a few rows of tracheides lyingnbsp;near one another and separated by rays. In certain circumstances theynbsp;might be taken for narrower intercalated segments of the woody ring.nbsp;Their appearance therefore favours the supposition that they participate in the further growth in thickness of the ring. Very instructivenbsp;pictures quite confirming this view are afforded by tangential sections, suchnbsp;as those described and figured in Brongniart^ and Williamson� (Fig. 33 A, A).nbsp;Here the rays which separate the wedges appear as broad fissures muchnbsp;elongated in the direction of the apex, of moderate depth, and often showingnbsp;at the margins traces of preserved parenchyma. But from the basal endnbsp;of every fissure of the kind there springs a broad cone-like process, thenbsp;elements of which are shown in longitudinal section below, in transversenbsp;section at the apex. It is the section through the lowest extremity of thenbsp;leaf-trace, so far as its course is vertical. And as the same picture is obtainednbsp;in every tangential section, whether made outside or inside in the wood, it

Williamson (6), t. 4. nbsp;nbsp;nbsp;^ Williamson (6), t. 4 ; G�ppert (1), t. 13, f. 31.nbsp;nbsp;nbsp;nbsp;^ Brongniart (7),

f- 3- nbsp;nbsp;nbsp;* Brongniart (7), t. 29, ff. 6, 7.nbsp;nbsp;nbsp;nbsp;Williamson (6), t. 5.

follows that the growth in thickness advances at the same rate in the ring of wood and in the trace, that the secondary elements of the trace at everynbsp;depth are in direct connection with the corresponding elements of the ring;nbsp;It is in perfect accord with this that the radial section (Fig. 33 C) showsnbsp;these large rays as simple intervals ^ the lower boundary of which is formed

by the arched convexity of the inner margin of thenbsp;trace. We see how this extends into the inner marginnbsp;of the ring of wood; we seenbsp;further that it is in directnbsp;connection by means of itsnbsp;secondary growth towardsnbsp;the outside with all successive layers of this wood.nbsp;Exactly the same structurenbsp;is found in quite youngnbsp;apices of Stigmariae, onlynbsp;in a smaller form, as isnbsp;shown by a ti'ansverse section of scarcely i millimetrenbsp;in diameter, which I sawnbsp;in Williamson�s collection.nbsp;This author has also published a figure of a similarnbsp;specimen

The secondary rays show quite normal customary conditions both on thenbsp;tangential and on the radialnbsp;section. In the former theynbsp;may be short and formed ofnbsp;a single row of cells, sometimes even be reduced to onenbsp;cell; they may also be higher and consist of from two to three I'ows of cells lyingnbsp;side by side. Their form is that of an ordinary brick placed on its longernbsp;edge. Authors differ much in their views of the nature of the tissue whichnbsp;filled the central cavity within the ring of wood during the life of the plant.nbsp;According to Williamson it was simply delicate thin-walled parenchyma,nbsp;remains of which are in fact sometimes found in the English Stigmariae

' Williamson (6), t. 6 ; Binney (1), IV, t. 21, f. 2 ; Hooker (4), t, 2, f. 13. ^ Williamson (6), t. 9.

lining the wall of the hollow cylinder. Similar remains of parenchyma are also figured by Goppert \ but these are according to his account traversednbsp;by isolated tracheal strands, which emerge further on through the primarynbsp;rays and give rise to the traces of the appendages. Though it is not easynbsp;to reconcile this statement with Brongniart�s ^ fine figure, yet it has beennbsp;adopted by Hooker ^ and by Binney That Binney has been deceived innbsp;this matter is evident from a glance at his figure. His tracheal strands arenbsp;only transverse sections of appendages of Stigmaria, which, as so very frequently happens, have found their way through exuberance of growth intonbsp;the interior of the specimen. Williamson, who has pointed emphatically tonbsp;this source of error has already suggested that this same mistake may benbsp;at the bottom of G�ppert�s statements ; and by fresh examination of thenbsp;original specimen, which the kindness of F. Romer placed at my disposal,nbsp;I have in fact satisfied myself that his view is correct. These statementsnbsp;therefore, on which Renault has relied so much for his conclusions, are notnbsp;to be trusted.

It appears however that this central tissue was not composed of parenchyma in all Stigmariae, for Renault has found that in his Stigmaria augustodunensis the whole of the space inclosed by the wood was fillednbsp;with a closed strand consisting of narrow tracheides. He has kindly shownnbsp;rne his preparations, which are all made from the same specimen, the onlynbsp;one which has the central strand preserved. Unfortunately we have receivednbsp;no account of the character of the surface, so that there is still room fornbsp;doubt whether the specimen belongs to Stigmaria.

The structure here described enables us to understand certain forms of preservation in the cast, which are noticed in the literature. Williamson �nbsp;gives the transverse sections of an inclosed cast, in which the inner cast isnbsp;Separated from the outer by a broad annular inteival, and is connected withnbsp;it only by thin rods of stone which cross the gap like spokes in a wheel. Itnbsp;is evident that in this case the two casts were formed at the same time.nbsp;And the ring of wood was also in existence at that time; the mineralnbsp;matter could only make its way into the primary rays, in which the tissuenbsp;had disappeared, and take casts of them. The subsequent disappearancenbsp;of the wood resulted in the formation of the empty space which is crossed bynbsp;the isolated rods, the casts of the primary rays. Von R�hH had previouslynbsp;published a similar specimen, and interpreted it quite rightly; but his interior cast is broken away, and only the outer portions of. the rods whichnbsp;represent the rays are preserved m situ.

� Brongniart (7), t. 29. nbsp;nbsp;nbsp;* Hooker (4).nbsp;nbsp;nbsp;nbsp;* Binney (4), f. 2.

Sections of the appendages in any desired direction are obtained in the greatest abundance by slicing the calcareous nodules from the coal-measures. The appendages traverse these nodules on all sides, formingnbsp;with fragments of fern-leaves much the larger portion of their contents.nbsp;Here too it is extremely rare to find all the tissues preserved alike. Innbsp;the following remarks we will first consider the usual state of the specimens.nbsp;A thin peripheral cylinder of parenchyma surrounds a broad cavity fillednbsp;with a structureless mass of matter, in which lies a second similar hollownbsp;cylinder inclosing the wood-strand. The broad tube of the outer cylinder,nbsp;which is generally circular on the transverse section, is often squeezed together, or even bent and folded in a great variety of ways, especially whennbsp;the appendages lie several of them close together or have had to forcenbsp;themselves through narrow orifices. The inner cylinder often lies free in thenbsp;centre of the cavity of the outer, or it may be connected with its wall bynbsp;means of a bridge-like plate of parenchyma which has been preserved \ Innbsp;other cases again it is quite excentric and rests against the wall of the outernbsp;cylinder, having evidently subsided into this position aftei the destructionnbsp;of the surrounding tissue. The inner cylinder too is by no means entirelynbsp;filled by the wood-strand, which touches it only at one point. The two arenbsp;separated everywhere else by a nearly circular intervening space, which,nbsp;moderate in its dimensions, is broadest exactly opposite the point of contactnbsp;a.nd decreases from this point in both directions. It has been already statednbsp;on p. 364 that the appendages sometimes branch dichotomously. I havenbsp;seen in Williamson�s collection several sections passing exactly through thenbsp;place of bifurcation. Then the xylem-strand separates by median divisionnbsp;into two lateral halves, which at first lie side by side in the expanded ovoidnbsp;inner cylinder but afterwards move further apart, while a bridge of parenchyma makes its appearance between them and divides the space into twonbsp;distinct compartments. Sections ^ a little higher up show the two compartments moved away from one another, and developed into separatenbsp;inner cylinders, which in many cases are still connected by traces ofnbsp;parenchyma, such as might easily have been preserved in the narrownbsp;intervening space.

Williamson ^ has given a figure of an appendage of the normal kind, but with all its tissues preserved. Here the space between the outer andnbsp;inner cylinder is filled with a layer of thin-walled tissue with its boundariesnbsp;on both sides sharply defined. The transverse section^ also is of quitenbsp;similar characters; only its outer cylinder is unusually large and shows twonbsp;distinct cell-layers, the inner one of which is remarkable for the thickness

'� Williamson (6), t. 13 and (1), xi, t. 53, f, 16. nbsp;nbsp;nbsp;^ Williamson (6), t. ii.

very seldom preserved. Figures giving the details of such cases will be found in Williamson h The inner layer, composed probably of loose parenchyma, is always entirely destroyed and its place occupied by structurelessnbsp;stone. This is usually the case also with the ring of bast, though I havenbsp;seen tolerably distinct remains of this portion of the rind in a specimennbsp;belonging to the collection at Strassburg. The outer rind on the othernbsp;hand which bears the appendages is, when present, generally well-preserved.nbsp;It consists of an outer layer of isodiametric thick-walled parenchyma, andnbsp;an inner tissue composed of radially disposed parenchyma-cells. Thenbsp;former may answer to the primary rind, the latter will be the product ofnbsp;a secondary zone of meristem on its inner margin. The boundary-linenbsp;between them is very distinctly marked in longitudinal sections ^ becausenbsp;of the difference of form in their elements, which in the primary parenchymanbsp;are isodiametric, in the inner layer on the contrary are elongated. Thenbsp;entire rind is of course traversed by the traces which pass out into thenbsp;appendages, and which here too, so far as we know from our present researches, show secondary growth, and consequently maintain unchanged thenbsp;characteristic form of the isosceles triangle with the acute angle pointingnbsp;inwards. Of the course of the traces in the inner rind which has disappeared we learn something from single specimens in a peculiar form ofnbsp;preservation. There is a magnificent specimen of this kind to be seen innbsp;the Museum at Breslau. This is an interior cast found in 1884 at the minenbsp;named Wildsteiner Segen in Upper Silesia; it is formed of fine-grainednbsp;slate-clay, and is split exactly in the radiate direction. The outer castnbsp;contains a number of very delicate linear traces preserved in coal, whichnbsp;pass through it in shallow curves with an outward direction, and arenbsp;partly it is true displaced and irregularly confused together. These are thenbsp;traces running to the appendages, which resisted decay longer than thenbsp;surrounding tissue, and were inclosed in the matter forming the cast.nbsp;Similar specimens are given in G�ppert�, and Williamson^ figures one ofnbsp;the kind, but it is not so well preserved. On the same table Williamson hasnbsp;given two more figures exemplifying another closely allied state of preservation. One of these is a petrified piece of wood, the other a piece of thenbsp;outer rind seen from the inside. Both are covered with irregularly curvednbsp;flattened vermiform cylindrical bodies, the petrified remains of the tracesnbsp;traversing the inner rind, which has otherwise disappeared; the traces arenbsp;also incrusted by surface-addition of the petrifying material. Exactly thenbsp;same state preserved in clay-ironstone is described in Lindley and Hutton�nbsp;as Caulopteris gracilis.

of all the cell-walls. In Hooker�s ^ figure no such differentiation of the layers is apparent; the wood-strand here lies excenti'ically inside a perfectly uniform mass of tissue. Whether all these variations point tonbsp;specific distinctions between the specimens which have been examinednbsp;cannot unfortunately be at present determined.

The character and outline of the central wood-strand are not found to be exactly the same in all transverse sections. A careful consideration ofnbsp;the differences which here present themselves is the more necessary, because

Renault in reliance upon them has arrived at somenbsp;important conclusions, tonbsp;which we shall have to recur more than once in thenbsp;succeeding pages. Thenbsp;cases to be distinguishednbsp;are chiefly three. First ofnbsp;all, there are the appendages in which the transversenbsp;section of the bundle showing secondary increase hasnbsp;the corresponding form ofnbsp;an isosceles triangle (Fig.nbsp;34 A), such as we have before observed in the trace-bundles in the wood andnbsp;rind ; only the mass of thenbsp;normal wood traversed bynbsp;fascicular rays is smaller, thenbsp;angle at the point of thenbsp;triangle is less acute. Thatnbsp;the bast-zone, when preserved, is to be found at itsnbsp;base, I have satisfied myselfnbsp;from a preparation in thenbsp;Botanical Department of the British Museum. Renault^ has figured anbsp;transverse section of this kind with remains of bast; figures showing thenbsp;ordinary condition will be found in Williamson� and Renault*.

Secondly, there are appendages of a different habit (Fig. 34 B, C, D), figured by Williamson � on the same tables as the preceding, in which thenbsp;wood-strand is composed of an ovate group of tracheides wide on trans-

verse section, and this group is succeeded on the side where it adjoins the inner cortical cylinder by a number of smaller ones with narrow lumina,nbsp;which form a projecting point. It is highly probable, as Williamsonnbsp;suggests, that this point is the initial group of the bundle. Sometimes anbsp;few other isolated broader elements are also found on its other side h whichnbsp;may be explained with Renault to be an indication of an inner wood-portion, a � bois centrip�te.� The size of the transverse section of bundlesnbsp;of this type varies extremely, the bundle being often reduced to a few ornbsp;even to a single one of the broad elements (Fig. 34 C), and then the initialnbsp;group suffers corresponding diminution in size, though it never entirely disappears. That the bundles in this, as in the preceding case, are collateralnbsp;and capable of secondary growth is evident at once from the inspection of anbsp;transverse section figured by Williamson which shows an unmistakablenbsp;bundle of Stigmaria (Fig. 34 Tgt;); but joining on to it on the side oppositenbsp;to the initial group is a well-developed layer of secondary wood with comparatively narrow elements disposed in regular rows. The bundles of thenbsp;category which we are here considering are often found in very thin andnbsp;small appendages; but it is hardly possible to lay down a rule on thisnbsp;point, for they occur on the other hand in the very broadest, so that apartnbsp;from the internal structure we cannot very well unite them as states of development with those of the first-mentioned type.

A third class again is composed of bundles, which resembling those of the second class in general habit are distinguished from them by the lessnbsp;regular form of the transverse section, which is triangular with the anglesnbsp;rounded off (Fig. 34 E). But the angle (a) which abuts on the innernbsp;cylinder is always more prominent than the other two {b, b), and in thesenbsp;also we find elements with a smaller transverse section, but varying in number and arrangement, and sometimes combining to form a narrow bandnbsp;which bounds one side of the bundle. Bundles of this kind have beennbsp;figured by Williamson � especially, and next to him by Renault who considers the three angles to be alike and to be initial strands, and thereforenbsp;conceives of the entire bundles as triarch root-strands, a view against whichnbsp;Williamson everywhere protests most vigorously. In fact the essentialnbsp;difference between the three angles, one of which only shows indubitablenbsp;signs of its initial character, and also the excentric position of the strandnbsp;which never touches the inner cylinder with more than this one angle, mustnbsp;necessarily give rise to very grave doubts. It has already been frequentlynbsp;pointed out, that it is very dangerous to determine the position of the initialnbsp;strands so directly from the diminution in size of the tracheides. And innbsp;this case it is quite possible to take an entirely different view of the matter

� Williamson (6), t. ii, f. 59- nbsp;nbsp;nbsp;� Williamson (6), t. n, t.nbsp;nbsp;nbsp;nbsp;�

* Renault (2), vol. i, t. 30, ff. 2, 3, 4, and vol. iii, t. A, ff. i, 2, 41=^� C

by assuming with Williamson that the collateral bundle has developed a few smaller elements on its outer margin, and that these were not disposed innbsp;any regular order, but were often crowded together at the angles. We maynbsp;even be able to see in them the first beginning of the secondary growth,nbsp;which, as has been before remarked, is certainly present in some cases innbsp;bundles of the second type. And this view even appears to me to be muchnbsp;simpler and more probable than that which Renault has developed. Butnbsp;this author has produced other arguments in support of his opinion. Henbsp;has figured the tangential section through the rind of an axis found near

Autun and this contains two transverse sections of traces, one of which is a collateral, the other a triarch stellate bundle. The two are innbsp;fact very different from one another. Thenbsp;stellate bundle, which is much macerated, isnbsp;cut through rather obliquely but showsnbsp;tracheides with round pits, such as nevernbsp;occur in genuine Stigmariae. The collateralnbsp;bundle also shows important differences, sonbsp;that it is more than doubtful whether thenbsp;specimen belongs to Stigmariae. Yet Renault ^nbsp;says himself: � It is possible that this Stigmarianbsp;maybe the rhizome of Sigillariopsis Decaisnei,nbsp;which shows in the structure of the wood ofnbsp;the stem a combination of radiate, reticulatenbsp;and dotted tracheides.� It is obvious thatnbsp;the specimen cannot in these circumstancesnbsp;prove anything in connection with thenbsp;characters of Stigmariae. Renault nextnbsp;maintains that in examining material fromnbsp;England, which doubtless belongs to Stigmariae, he has found appendages with a triarch wood-strand, fromnbsp;the angles of which proceed delicate vascular bundles destined fornbsp;lateral roots, and he has more than once reproduced the preparationnbsp;which is intended to prove this view� (Fig. 35). The specimen shows anbsp;wood-strand which in form comes very near to the second type; but it isnbsp;only the angle touching the inner cylinder which has the appearance of annbsp;initial strand, while this would be a forced interpretation of the other two.nbsp;The supposed lateral root-bundle connects with the angle which is evidentlynbsp;an initial angle, and the longitudinal view of it shows a single tracheide; butnbsp;the nature of this bundle is very doubtful. I was unable to recognise the

tracheide as such with any certainty in the preparation which Renault most kindly demonstrated to me; and he told me indeed that it could once benbsp;more plainly seen. But apart from this I am chiefly impressed by the factnbsp;that neither I nor any one else have been able to find anything of the kindnbsp;before or since in material from England, which has been examined over andnbsp;over again. And yet according to Renault these lateral roots occur frequently all round the appendages; he says distinctly ^: �It seldomnbsp;happens that a transverse section through any part of a radicular appendagenbsp;does not disclose indications of the first beginning of a rootlet at one of thenbsp;three angles of the primary wood.� Unfortunately he gives us no morenbsp;precise information about these � indications.� From these doubtful statements he proceeds to the conclusion that the surface of these appendagesnbsp;must show three vertical longitudinal rows of � cicatricules.� That thenbsp;presence of these scars has never been ascertained by direct observation, henbsp;attributes to their minuteness (they are supposed to be only from one to two-tenths of anbsp;millimetre in thickness), and to the insufficientnbsp;state of preservation of the specimens.

Lastly, the point of insertion of the appendages on the axis in Stigmariae showsnbsp;some further anatomical peculiarities (Fig. 36),nbsp;and it is Williamson again who has directednbsp;his attention especially to this subject Thenbsp;vacant space which separates the outer andnbsp;the inner cylinder from one another comes tonbsp;an end quite suddenly exactly at the point ofnbsp;attachment. It is cut off by a transversenbsp;diaphragm formed of stout tissue, and represents the portion of thenbsp;outer rind of the axis beneath the appendage. The diaphragm isnbsp;traversed by the trace-bundle, which, as it emerges to enter the appendage,nbsp;IS still surrounded for a short distance by a sheath of the stout parenchyma which ultimately comes to an end in the inner cylinder. Horizontal sections of the diaphragm-plate are seldom obtained; the only onenbsp;which I find in my preparations agrees perfectly with the one whichnbsp;Williamson has figured 'h Within the stout plate of parenchyma is a weaknbsp;bundle-trace, which certainly belongs to the type of the second class described above. In these specimens therefore the secondary growth in thenbsp;traces must have ceased while they were passing through the rind, if therenbsp;was any growth of the kind,�a point which in the absence of transversenbsp;sections of these specimens cannot be certainly proved. Analogy with the

many other transverse sections which have been studied is the only probable argument which can be advanced. But since we find great numbers ofnbsp;detached appendages which inclose a bundle endowed with secondarynbsp;growth, there remains only one of two alternatives ; either growth in thickness reappeared in these appendages, or the trace in them passed throughnbsp;the basal diaphragm in another form than that of the specimen hithertonbsp;studied, namely, with retention of the secondary wood. Should the latternbsp;be the right conclusion, we should then be obliged to assume that therenbsp;were distinct species of Stigmaria differing from one another in this respect.nbsp;Renault indeed states that he has seen very different forms of trace at thenbsp;same time on one and the same axis, but his arguments in proof of this,nbsp;which we must notice again presently, are not to my mind conclusive. Nornbsp;can the facts as here given be reconciled without forced interpretationsnbsp;with Williamson�s^ viev/, who sees in the different trace-types only thenbsp;pictures of different portions of one and the same organ of the .same plant.nbsp;These are just the questions in which the anatomy of the parts is not anbsp;decisive guide in any direction. There are no successive sections, as far asnbsp;I know, of appendages still attached to manifest axes of Stigmaria; butnbsp;these alone can clear up the questions which we have been considering.

Many very different accounts have been given in the course of time both of the position of Stigmariae in the system and of their morphologicalnbsp;differentiation. Opinion has been more divided on these points than in thenbsp;case of any other fossil vegetable remains, and no full and certain determination of them has been obtained up to this day in spite of the almostnbsp;overwhelming literature. In proceeding to review the efforts which havenbsp;been made to effect this purpose, we may very well avoid any lengthy consideration of the comparisons proposed by earlier authors with Opuntiae,nbsp;Cacaliae, Ficoideae, Stapeliae, Aroideae, and even with Palms. A summary notice of them will be found in G�ppert ^

The first person who suggested, though on weak grounds, a close connection of our remains with Lycopodinae, and especially with Iso�tes, was Brongniart�. His idea, which did not at first meet with much approval,nbsp;won its way in time to recognition when better arguments could be adducednbsp;in its support, and may now be said to be very generally accepted. Thenbsp;first distinct, and for some time the standard, account of the structure ofnbsp;these plants was communicated by Bindley and Hutton^, and was foundednbsp;on the branched specimen discovered in the roof of the Bensham seam innbsp;Jarrow mine, and figured by them. This .specimen, which being fixednbsp;in the roof can be seen only from below, shows twelve well-preserved innbsp;some cases dichotomously divided Stigmaria-branches, which even have the

appendages still attached and spreading obliquely like rays from a central mass. The ideal longitudinal section appended by the authors gives therefore the outline of a cupola or dome to the entire branch-system. Theirnbsp;conclusions from these facts, with the aid of the knowledge which had beennbsp;previously gained, are as follows : i. That Stigmaria was a land-plant of lownbsp;growth, whose branches spread regularly from the common centre, and atnbsp;length branched dichotomously. They are not certain whether the domednbsp;centre � is a generic character or not; they think it possible that the plantnbsp;grew on a small hillock, from which its branches spread downwards innbsp;every direction. 2. That it was a succulent Dicotyledon. This is concluded from Steinhauer�s previously mentioned observations on the centralnbsp;cylinder. 3. That the roundish scars on the surface are the places wherenbsp;the leaves have separated from the stem. It is cautiously concluded fromnbsp;their regular quincuncial disposition all round the stchn that they couldnbsp;not properly have been roots. 4. That these leaves were cylindrical andnbsp;fleshy. The authors rightly attach little value to comparisons with certainnbsp;groups of Dicotyledons, for � it must be confessed that this is but a rudenbsp;kind of analogy V Fourteen other similar specimens were soon after discovered in the same mine, some of which were removed from it. Thesenbsp;too were discussed by Lindley and Hutton in the Introduction to thenbsp;second volume of their work One of the specimens removed from thenbsp;naine, showing the upper side, is figured in the same work From thenbsp;fact that the appendages spread at right angles in every direction and lienbsp;across the bedding, it is concluded that the plants grew � in the soft mudnbsp;most likely of still and shallow water.� These views, which accorded wellnbsp;with the state of knowledge at the time, were generally accepted not innbsp;England only but also on the Continent, where they found warm supportersnbsp;especially in Corda^ and Sternberg�, and in Goppert� also, thoughnbsp;the latter, doubtful about their affinity with Dicotyledons, preferred tonbsp;regard them as � cryptogamous Monocotyledons, or as intermediate formsnbsp;Connecting Lycopodiae with Cycadeae.

An entirely new impulse was given to the question in the years 1845 and 1846 by Binney�s�^ discovery of erect stumps of Sigillaria-stems, eachnbsp;of which terminated below in four root-branches with the character ofnbsp;Stigmariae. The three first specimens were discovered as early as 1843nbsp;at St. Helen�s near Manchester. When they came to be examined, theynbsp;had already suffered great damage through exposure, and if there can benbsp;no doubt of their being Sigillariae, yet their Stigmaria-roots were not toonbsp;convincing, especially in the figure. But the stump with roots discovered

in the Victoria mine at Dukinfield near Manchester ^ at once removed the doubts which still existed. It was found in the floor of the cannel-seam,nbsp;whence it was got out and carried to the Manchester Museum, of which it isnbsp;at present one of the chief ornaments. The branches of the roots, some ofnbsp;which may be followed to their extremities, ran, bifurcating here and there,nbsp;in the underclay of the seam, and proved to be indubitable Stigmariae.nbsp;The stump of the stem, measuring fifteen inches in height and four feet innbsp;circumference, shows plainly the characters of a Syringodendron. I havenbsp;been able to satisfy myself on all these points by personal examination.nbsp;When Binney on the strength of those observations gave it as hisnbsp;decided opinion that Stigmariae are the root-stocks of Sigillariae, he wasnbsp;met by the expression of great doubts on the part of many Continentalnbsp;observers, though Brongniart ^ at once and G�ppert � at a later time tooknbsp;the part of the English botanist. The objections which were raised againstnbsp;this connection of Stigmaria with Sigillariae are for the most part notnbsp;difficult to meet. They cannot taken all together hold their own againstnbsp;the long series of stems, which have since that time been found in actualnbsp;union with Stigmaria-roots. For if Goldenberg * is of opinion that thenbsp;dome-shaped central stock in Lindley and Hutton�s specimens shows nonbsp;surface of fracture, and cannot therefore be a mutilated form, the answer isnbsp;that this surface may very well have disappeared or become obscured bynbsp;lateral pressure and the formation of slickensides. The same author saysnbsp;further on : � As regards the observation of Binney and Hooker cited above,nbsp;on which so great weight has been laid, I am willing to believe that thesenbsp;gentlemen observed scars very like the scars of Stigmariae on roots whichnbsp;were still attached to stems of Sigillariae. Such scars are to be found onnbsp;all fossil plants, in which the branches of the root had root-fibres of thenbsp;thickness of a quill,� amp;c. If Goldenberg had seen the specimens atnbsp;Manchester he would not have written thus, for they are so characteristicnbsp;that every doubt disappears. We cannot of course enter upon the questionnbsp;of the supposed fructifications mentioned on p. 265, which Goldenberg discovered and has appealed to as an argument against Binney�s view, so longnbsp;as their real nature is not better ascertained. Another determined andnbsp;formidable opponent appeared in 1870 in the person of Unger. He says�:nbsp;� To suppose Stigmaria to be the root of Sigillariae, to which it is said tonbsp;have been found attached, is in a word a morphological impossibility,nbsp;apart from the fact that the former presents all the characters of annbsp;independent plant.� He is careful indeed not to say what characters henbsp;means. He rests his judgment on the appendages, which he says have notnbsp;the morphological characters of lateral roots. This must be admitted.

But it must be remembered that subterranean organs may also be rhizomes, and in that case the objection falls to the ground. Brongniart \ who hadnbsp;similar difficulties, was much more cautious. But when Unger goes on tonbsp;maintain that it is impossible to reconcile the anatomy of Stigmaria withnbsp;that of Sigillaria he raises an objection which deserves all attention andnbsp;requires to be properly examined. In comparing the two togethei, wenbsp;encounter really two important points of difference. First there is thenbsp;growth in thickness of the trace-bundles of Stigmaria, and we find nothingnbsp;that resembles growth of this kind in Sigillaria; but the more importantnbsp;point is that in Sigillaria, as we have seen, there is no layer of primarynbsp;wood (bois centrip�te) differentiated into irregular bundles in the peripherynbsp;of the pith, such as we observed in Stigmaria on the inner side of thenbsp;secondary growth. We are therefore obliged to assume that the centralnbsp;cylinder in Stigmaria was purely parenchymatous, with a network only innbsp;Its periphery of weak, probably normally disposed, tracheal strands, withnbsp;which the growth in thickness connects at once and immediately, as in thenbsp;stem of Botrychium. This would explain the fact, that we find it impossible or difficult to distinguish the wedges of wood from the primary strands,nbsp;that the structure of the youngest extremities is essentially the same as that ofnbsp;the older parts. In Stigmaria augustodunensis, though its connection withnbsp;the group is not perfectly assured (see p. 273), the entire central strand,nbsp;which is parenchymatous in Stigmaria ficoides, is composed of tracheides.nbsp;How the one form of structure passed into the other at the base of thenbsp;Speight stem we cannot tell, nor is it likely that we shall ever find thisnbsp;portion of the plant with the structure preserved. But the difficulties innbsp;this case are certainly much less important than those which would arise innbsp;reconciling the structure of stem and root in our living plants, if we hadnbsp;only unconnected fragments of them before us.

A number of stems with Stigmaria-roots attached were described in the years 1846, 1848, and 1849 by Richard Brown \ from the Carboniferousnbsp;formation of the island of Cape Breton in Nova Scotia. In none of themnbsp;could there be any doubt with regard to the nature of the diverging root-system. The stems, it is true, which were described in Brown�s first publication, could not be certainly determined; but those of the third worknbsp;Were shown to be genuine Sigillariae (Fig. 37 C). Those of the yearnbsp;1848 were described by Brown as Lepidodendrae; but judging by thenbsp;figures I can only see the impression of Dictyoxylon-structure, and asnbsp;this occurs also in the rind of Sigillaria, Lyginodendron, Heterangium, andnbsp;other forms, its presence cannot well be employed to prove that Lepidodendrae also had Stigmaria-roots. If the view expressed by Rich. Brown

nevertheless met with a favourable reception, it was only because there appeared to be other reasons compelling its adoption; Geinitz fornbsp;example, and Schimper ^ after him had insisted on the extraordinarynbsp;abundance of Stigmaria ficoides in the sandstones of the Culm, in whichnbsp;there are no Sigillariae but great numbers of Lepidodendrae and Knorriae.nbsp;This is the case at Burbach near Thann, and also near Hainichennbsp;and Ebersdorf in Saxony, and in the anthracites of the Roannais �; andnbsp;Geinitz * expressly states that the roots of Lepidodendron rimosum. whichnbsp;he examined in the mines at Niedercainsdorf in Saxony, showed quite thenbsp;characters of Stigmariae. The views of all these authors have been confirmed by the discovery of a stem from the quarries at Burbach, which isnbsp;now in the Museum at Colmar. Schimper� says that this stem has thenbsp;characters of Knorria longifolia above, lower down those of Didymophyllumnbsp;Schottini and Ancistrophyllum, and that an indubitable Stigmaria with onenbsp;bifurcation is attached laterally to its base. When I saw the specimen,nbsp;some years ago it is true, it seemed to me also quite convincing.

Hitherto we have been exclusively occupied with the question of the kind of stems which ended below in Stigmariae ; it remains to describe thenbsp;form of the bases of these stems, and of this we have very accurate knowledge from the number of specimens which have been met with in recent times.nbsp;The most important fact to notice is that a tap-root has never in any casenbsp;been found as the direct prolongation of the stem, but that the latter endsnbsp;abruptly, and only gives rise to lateral branches which run in a horizontalnbsp;direction and soon assume the character of Stigmariae. These divergingnbsp;main branches are always four in number, and being connected togethernbsp;like the arms of a cross, they inclose the Somewhat depressed lower surfacenbsp;of the base of the stem. So much had been already observed by Lindleynbsp;and Hutton in their stems. The central depression may be seen, when thenbsp;preservation is good, to be traversed by four furrows which meet in thenbsp;central point, and are the boundaries of the areas of origin of the fournbsp;Stigmariae. As good examples of this regular division into four, which itnbsp;seems natural to refer to rapidly repeated dichotomy, may be mentionednbsp;Richard Brown�s � specimens which were noticed on the previous page, thenbsp;stumps from Bradford described by Binney ^ and preserved in the Museumnbsp;at Leeds, G�ppert�s � specimens from Schatzlar, and Williamson�s ^ extremely beautiful new figures (Fig. 37 B). If Temme�s^� stem from Piesbergnbsp;is represented with six roots, this is no doubt because two of its fournbsp;original branches have each formed a new bifurcation at once and without

� Geinitz (5) and (8). nbsp;nbsp;nbsp;� Schimper (4).nbsp;nbsp;nbsp;nbsp;� Grand� Eury (1), p. 411.nbsp;nbsp;nbsp;nbsp;�* Geinitz (5),

p. 36. nbsp;nbsp;nbsp;� Schimper (1), vol. ii, Part I, p. 117.nbsp;nbsp;nbsp;nbsp;� Brown, Rich. (1) and (2).nbsp;nbsp;nbsp;nbsp;� Binney

(7), ff. 5, 6. nbsp;nbsp;nbsp;* Goppert (14), p. 79, t. 15 and (3), t. 36, ff. i, 3 ; Romer, F. (1), p. 232.

any considerable previous elongation. And the like may certainly be assumed in the case of all specimens in which numerous lateral branches spring immediately from the base of the stem, and among them of Binney�snbsp;and Harkness� ^ stems from St. Helen�s, of Rich. Brown�s � of the year 1849nbsp;from Cape Breton, of the stem in the Museum at Bonn from the Holz-hauertha! near Saarbr�cken described by Goppert ^ and of the stem quitenbsp;recently found near Bradford(Fig. 37 A), for a photograph of which takennbsp;on the spot I am indebted to the kindness of Mr. Cash. The repeatednbsp;dichotomy is most clearly seen in the two last specimens and in one of

Brown�s, and was duly noticed in the description of the Bonn stem given by Weber and printed by Goppert

A special peculiarity is observed in one of Brown�s � stumps (Fig. 37 O- On the under side of its Stigmariae are blunt conical processes directednbsp;vertically downwards, and with their surface covered with transverse wrinklesnbsp;of apparently accidental origin. The discoverer notices particularly thatnbsp;they are arranged in two circles, the inner containing sixteen processes, thenbsp;outer thirty-two. The figure it is true does not point to these numericalnbsp;relations, but it shows that each process, a � tap-root � according to Brown,

is developed at the base of a dichotomy, as the roots are developed beneath the place where the stem branches in Selaginella. From this we may atnbsp;least conclude that these conical bodies are not objects of casual occurrence,nbsp;but that they stand in some distinct though not yet determinable relationnbsp;to the structure of the stem.

If now from all the circumstances which have been discussed there can no longer be any doubt that Stigmariae are simply members of stems ofnbsp;Sigillarieae and Lepidodendreae which performed the functions of roots,nbsp;and that they must be removed from the system as a distinct group ofnbsp;plants, yet a few further facts connected with the positions in which theynbsp;are found may be brought forward in confirmation of this view. It hasnbsp;long been known that in Westphalia, in England, in Canada and elsewhere,nbsp;the floor of the coal-seams is usually formed of beds of clay of varyingnbsp;thickness, which are traversed by countless Stigmariae. These beds arenbsp;called in England Stigmarian underclays. These Stigmarias appear innbsp;general to have no connection with the seam of coal, but Grand� Eury^ tellsnbsp;us that he has observed a direct transition of the kind at Dombrowa in thenbsp;coal-field of Poland and Upper Silesia. That the plants must have grownnbsp;in the substance of these beds of clay is shown by the arrangement of theirnbsp;appendages already noticed by Lindley and Hutton ^; when the appendagesnbsp;spread on all sides at right angles to the axis they lie parallel with thenbsp;bedding, but when they are directed upwards or downwards they are atnbsp;right angles to it. Consequently, if they grew so luxuriantly in the mudnbsp;of the Carboniferous swamps on the surface of which the formation of coalnbsp;began, they cannot well have been organs of assimilation, but must havenbsp;been adapted rather to take up material from the substratum. They arenbsp;distributed in like manner through the roof of the seams, but are not sonbsp;abundant there, and they seldom reach the level of the coal itself but arenbsp;separated from it by a layer, though often only a thin layer, of the clay.nbsp;This is intelligible, if we consider that a certain time must have elapsednbsp;before a fresh vegetation of Stigmariae could commence on the mud whichnbsp;covered the Carboniferous swamp, and which was deposited through thenbsp;irruption of streams of water from other quarters. As they were safe innbsp;their mud from being floated away by running water, it was easier for thenbsp;cylindrical axes when once formed to remain in their natural position, andnbsp;therefore it is that they are found so abundantly in the case of Stigmariae,nbsp;while those of the stems both of Sigillarieae and Lepidodendreae are ofnbsp;rare occurrence (see on p. 265).

Further, the study of the seams themselves and of the calcareous nodules sometimes present in them gives occasion to similar considerations.

An abundance of the appendages is to be found in every section of the nodules, even where they contain no axes of Stigmariae. These appendagesnbsp;in the exuberance of their growth have penetrated in every direction throughnbsp;the heap of vegetable fragments which forms the chief mass of the nodules,nbsp;and they make their way into every crevice and into every bit of softenednbsp;wood. The hollow medullary cylinders of stems of all kinds are foundnbsp;traversed by them lengthwise, and often by whole bundles of them. Somenbsp;appendages may inclose a number of others with a narrower lumen (Fig. 3^)'nbsp;We saw on p. 273 how in this case they may give rise to mistakes. But allnbsp;these things prove that they grew luxuriantly in this organic soil, and thatnbsp;they did not merely sink down in it at some later period. As the roots ofnbsp;trees develope abundantly at the present day in the rotten wood of thenbsp;primeval forests in every zone, and spread abroad in it copiously in everynbsp;direction, so did the Stigmariae also in the Carboniferous period. They are also frequently preserved innbsp;the coal of the seams, but then they are alwaysnbsp;flattened in the planes of stratification; manynbsp;instances of this kind will be found in Grand Euryknbsp;The flattening took place therefore after the formationnbsp;of the calcareous nodules in the masses that were laidnbsp;in their final resting-place, and while these were in thenbsp;net of subsiding. Stigmariae must accordingly havenbsp;been continually present during the formation of thenbsp;seams, and on the spots where they were being formed.

And, to sum up briefly what has been said, if the Stigmariae were adapted to grow at one time innbsp;the inorganic slime of the later underclays, presumably at the bottomnbsp;of the water, and at another time in the organic mass of the seamnbsp;itself, in the latter case perhaps forming part of the matted growth coveringnbsp;the surface of the water in the coal-swamps, it is plain that they must havenbsp;possessed a developed faculty of adaptation to external circumstances ofnbsp;Very different kinds.

With this result the physiologist may rest content; morphology must institute some further enquiries into the character of the separate membersnbsp;of the stock in Stigmariae. Here again opinions are widely divided.nbsp;Brongniart^ himself had remarked that some of their characters do notnbsp;quite agree with those of recent roots, and though he does not think thatnbsp;this is a matter of much importance, still he says : � The only factnbsp;which is opposed to this view is that the rootlets are not disposed innbsp;limited longitudinal rows, but in quincunces.� Then Schimper � insisted

more strongly on this point, and made use of it, in conjunction with fresh arguments, as the foundation of another view, namely, that thenbsp;axes were rhizomes and their appendages leaves. In this case the Sigil-larieae and Lepidodendreae must, as he argues, be compared with thenbsp;rootless stock of Psilotum, though the leaves, which are present in Stig-maria, are quite wanting on the rhizome-shoots of the other plant. Thisnbsp;view is very vigorously opposed by Williamson^. Putting aside thenbsp;occasional bifurcations and the puzzling scars in the angles, he appealsnbsp;more particularly to the anatomical structure, which he finds to be almostnbsp;identical with that of the rhizophores of Selaginella Martensii. The twonbsp;organisms are certainly like one another in appearance, and this might benbsp;expected, since we have to do in the one case with the rare monarchnbsp;radial strand, in the other with a collateral bundle. It is only from thenbsp;position of the bast or cambium that the difference between them can benbsp;determined. However, the resemblance does not go so far as might benbsp;imagined from Williamson�s ^ figure of the transverse section of Selaginella,nbsp;which is correctly drawn indeed, but wrongly explained. The large cellsnbsp;opposite the initial group, which Williamson supposes to be the bast, arenbsp;really parts of the wood-strand, tracheides in the young state ; the real bastnbsp;is to be sought in the small-celled peripheral zone marked C. The bundle innbsp;this case is late in reaching its ultimate development, and hence the mistake,nbsp;which is easy to understand. But it cannot be denied that Schimper�s ideanbsp;entirely gets rid of most of the difficulties. There is first the fact that thenbsp;dichotomously branched axes develope their appendages in progressive succession, On the supposition of a branch-system consisting of similar membersnbsp;(roots and lateral roots), this would imply a different structure and originnbsp;for the members of the same generation. And this would certainly benbsp;remarkable and without direct analogy in living vegetation, even supposingnbsp;the distinction between progressive and dichotomous branching to have lostnbsp;its importance to the same extent as at the present day. But if we considernbsp;the Stigmariae to be leafy rhizomes, everything is as it should be. It hasnbsp;been repeatedly observed before that the position of the appendages doesnbsp;not agree with that of lateral roots, but that it does agree very well withnbsp;that of the leaves; that they leave scars behind them of a definite shapenbsp;when they drop off, which never or at least only very rarely happens withnbsp;roots, is a point which Schimper regards as most important. The specimennbsp;in my possession and described above on p. 268, which has the vegetativenbsp;points, may also really favour Schimper�s view ; for there the young appendages approach nearer to the apex than is ever the case with roots onnbsp;account of the root-cap, for which there is too little room left. There is.

moreover, the distinct formation of buds, the hyponasty and epinasty of which would also be something quite unheard of in the case of roots ; and itnbsp;rnay be remarked by the way that this formation of buds proves to my mindnbsp;that the Stigmariae were exclusively adapted to a soft pulpy environment,nbsp;for this would be unsuitable and almost impossible in solid ground.

The latest elaborate examination of the question which we are considering has come from the pen of Renault^. He, too, takes Schimpers view, and regards the greater number of Stigmariae at least the exceptionsnbsp;will be noticed presently�as rhizomes. He differs from him to the extentnbsp;of distinguishing the appendages into two classes, one of leaves, the othernbsp;of adventitious roots. This distinction he rests entirely on the differencesnbsp;in anatomical structure described above on p. 276. I have, however, alreadynbsp;shown that these differences may very well be interpreted in a different manner.nbsp;There are absolutely no external characters present, which could serve fornbsp;this distinction into leaves and fibrous roots; and when Renault ^ says: �Innbsp;the cortical region the number of bundles belonging to roots becomesnbsp;greater because the roots are to a great extent of later formation than thenbsp;cylinder of wood; their late appearance gives rise to supernumerary spirals,nbsp;or to scars irregularly distributed on the surface of certain specimens,^ itnbsp;appears to me that this short sentence, which has no particular prominence in the text and really contains two unproved assertions, is the Achillesnbsp;heel of the whole argument. First of all, specimens with � supernumerarynbsp;spirals� are supposed to have been unusually abundant. For Renaultnbsp;assumes as a necessary consequence of his view, that the portions of anbsp;shoot which have appendages with the character of leaves come fromnbsp;the immediate vicinity of the apex, that those which bear roots onlynbsp;belong to the older lower part of the shoot which has lost its leaves,nbsp;while the portions which are furnished with both kinds of organs represent a middle region. And then it must be assumed that the oldernbsp;portions of rhizomes must be more abundant in the fossil remains than thenbsp;youngest. Now all Stigmariae, as far as I know, exhibit essentially thenbsp;same regularly quincuncial arrangement of the scars. I have never beennbsp;able to see anything of the � supernumerary spirals� and other irregularities,nbsp;though I have examined a great many specimens and figures for this purpose,nbsp;nor have I seen any specimens in Renault�s collection which prove thenbsp;point. In the sections tangential to the surface of a Stigmaria which henbsp;has figured and which pass through both kinds of organs, there is nonbsp;certainty that all the sections are really sections of the same axis. In thenbsp;transverse sectionthe �root� marked c certainly does not belong to thenbsp;specimen, but is merely a later introduction.

^ Renavilt (2), vol. i, and Introd. to vo\. in, and (10). (10), t. I, ff. 3 and 7.nbsp;nbsp;nbsp;nbsp;^ Renault (10), t. i, f. i.

according to external marks observed in loco, and to these he gave the names Stigmaria and Stigmariopsis. To the latter genus belong the rootstocks which are found in connection with Syringodendron-casts of Sigil-lariae. But the difficulty of carrying out this distinction will be apparentnbsp;to everyone who considers the indefiniteness of the characters employed.nbsp;Grand� Eury ^ himself says; � There are other stigmarioid growths whichnbsp;have been confounded with true Stigmariae when fragments of them onlynbsp;have been examined, but a complete knowledge of them enables me tonbsp;distinguish them,� amp;c., and further on ^� These differences are complete innbsp;the extreme cases. But though important they diminish in some intermediate cases ; and this is why, after having at first removed Stigmariopsisnbsp;from Stigmaria, I now bring them near together within the limits of thenbsp;same family.� But his characters are of as little use botanically speakingnbsp;as those of Renault. The latter author endeavours to save Stigmariopsisnbsp;by means of this theory of � stigmarhizes,� which are supposed to benbsp;developed only when a branch of a Stigmaria-rhizome raises itself intonbsp;the air as a Sigillaria-stem. Renault ^ says distinctly: � When the rhizome continued to grow as a Sigillaria, the latter put forth on its paitnbsp;voluminous dichotomous roots of stigmarioid form (Stigmariopsis), onnbsp;which only radicular appendages were developed.� And this brings us tonbsp;the history of development.

The same circumstance, which formerly made continental botanists so cautious and reserved in the matter of the connection between Sigillarianbsp;3^nd Stigmaria, gave rise, as soon as this connection was acknowledged, tonbsp;attempts to reconstruct the history of development of Sigillariae. Then itnbsp;became necessary to explain the fact, that in some deposits Stigmariae arenbsp;found almost or entirely without the stems belonging to them, that thenbsp;underclays are sometimes thirty feet thick and yet contain nothing butnbsp;Stigmariae, as we learn from Lesc][uereux The same author also statesnbsp;that in some localities in North America layers of underclay above thenbsp;ground are covered over considerable spaces by axes which cross onenbsp;another and creep in all directions, without any trace of stems to whichnbsp;they were attached. G�ppert� was the first who attempted to give annbsp;explanation of all this from the history of development. On occasionnbsp;of a tour of investigation in* the chief mountain district of Westphalianbsp;by direction of the Board of Trade in the year 1850, he found in thenbsp;President mine near Bochum in the middle of the coal of the Sonnen-schein seam some peculiar nodules, round or elongated and sometimesnbsp;divided at the extremities, and consisting of stone or pyrites. Outside

* Lesquereux (ll, vol. i, and vol. ii, p. 500; Grand� Eury (2), p. i8i {.3\ p. 188.

On the other hand, we know that the trace-bundles, wherever they are examined, are found to originate on the inner margin of the wedges of woodnbsp;in the axis of Stigmariae, that their basal portion runs through the primarynbsp;rays and grows in thickness pari passu with the neighbouring wood.nbsp;If then so many late-formed adventitious members as Renault supposesnbsp;really appeared on these axes, we should expect to find their trace-strandsnbsp;somewhere or other, though they could not of course have made theirnbsp;way so far as the inner margin of the ring of wood. But no one has yet succeeded in finding them ; and if the plant was capable of forming normal rootsnbsp;as organs of absorption, it must seem a surprising piece of luxury that itnbsp;should at the same time have leaves adapted to the same function.nbsp;Functional adaptation of certain organs to supply the place of others thatnbsp;are wanting is a frequent phenomenon, but I know of no analogous instancenbsp;of such a biological arrangement as is here described.

It will be apparent from the above remarks that, until proof to the contrary is forthcoming, I must hold to the opinion that all appendagesnbsp;are members of the like morphological character. It matters little whethernbsp;they are supposed to be roots or leaves, and it would perhaps be well tonbsp;avoid any such precise definition of ideas in the case of organs, which havenbsp;no direct analogues in the whole of our recent vegetation.

Besides his � stigmarhizomes,� of which we have hitherto been speaking, Renault considers that he has found Stigmariae which were real roots, beingnbsp;supposed never to have borne foliar appendages at any time, but alwaysnbsp;only root-appendages. These are his � stigmarhizes,� of which however henbsp;has so little to say that he dismisses them in less than the space of a pagenbsp;of his monograph while he devotes fourteen pages to the description ofnbsp;the rhizomes. The only figure of the transverse section of a � stigmarhize �nbsp;which the work contains is taken from a fragment from Autun ^; and thenbsp;anomalies in structure which it exhibits, and for which the original shouldnbsp;be compared, make me think that it can hardly be a Stigmaria at all. Asnbsp;even Renault�s reply� to Williamson�s and Hartog�s objections affords nonbsp;better explanation of the whole matter, we are compelled to ask what itnbsp;was that suggested to him the idea of these � stigmarhizes.� The further wenbsp;search into the literature, the more we shall be convinced that the scantynbsp;array of facts which it supplies can scarcely by itself have given occasionnbsp;to it. The truth is that the theory of � stigmarhizes � rests entirely on certainnbsp;views of Grand� Eury which appeared in his first work and which henbsp;subsequently carried out still further Grand� Eury attempted to distinguish the entire group of fossils which we are considering into two genera.

they showed Stigmaria-scars, and on many of them no surfaces of fracture could be seen. For this reason G�ppert pronounced these nodules to benbsp;young individuals, perfectly preserved all round, which would branch bynbsp;further bifurcation of their extremities and develope into the well-knownnbsp;rhizomes. He supposed the tuber-like stock to have been formed bynbsp;irregular swelling at some spot in its middle portion, and that it might undernbsp;favourable circumstances grow into a Sigillaria-stem, or in other casesnbsp;continue for a very long time or even always in its original condition. Fornbsp;the mode of development of this tuber-like stock he appeals to an observation of Steinhauer who saw several branches of Stigmaria proceed from anbsp;central tuber from one to four decimetres thick, and reach a length ofnbsp;twenty decimetres. And he himself on the same journey in Westphalianbsp;observed a similar specimen on a perpendicular wall of Carboniferousnbsp;sandstone at Kirchhorde near Dortmund, varying from fifty to a hundrednbsp;feet in height, and has given a figure of it It was a tuber-like body ofnbsp;irregular form some two feet thick, having branches of Stigmaria going offnbsp;from it in every direction,�the figure gives four of them,�but with theirnbsp;extremities not preserved or hidden in the stone. The account has nonbsp;doubt an air of truth about it, and explains satisfactorily that which it hadnbsp;to explain ; and recent vegetation supplies analogous cases for comparison,nbsp;as in Psilotum and less exactly in Corallorhiza, Epipogium and other plants.nbsp;This is why it has so greatly influenced the accounts given by all subsequent authors, but the foundation on which it rests is not really of muchnbsp;value, for the tuber-like bodies from Bochum from G�ppert�s collection, fornbsp;some of which I am indebted to F. Romer, are in fact shapeless objects innbsp;part slicken-sided, and can prove nothing.

While G�ppert supposes all Stigmariaeto spread like spokes of a wheel from a central stock or from the base of Sigillariae, and to elongate in everynbsp;direction with repeated bifurcations, the PTench authors Renault � andnbsp;Saporta and Marion''^ are of a somewhat different opinion on this point.nbsp;The first says, for example �: � The life of a Stigmaria was undoubtedlynbsp;confined for a long time to the almost unlimited production of dichotomousnbsp;ramifications.� But then single peripheral extremities of branches of thesenbsp;rhizomes are supposed to become erect and as � aerial buds � to give rise tonbsp;the stems, which in their turn put forth two proper roots (� stigmarhizes �)nbsp;at their base. Hence the four diverging and repeatedly bifurcating branchesnbsp;of the base of the stem must be � stigmarhizes,� and somewhere betweennbsp;them must be the place where the rhizome-shoot was broken off, the apexnbsp;of which grew upwards in the form of a stem. Putting aside the purelynbsp;hypothetical nature of these � stigmarhizes,� the facts do not give the smallest

support to this assumption, as has been justly urged by Williamson and Hartog h It is true that they themselves go too far again in the followingnbsp;sentence ^: � two or four shoots of Stigmaria of equal size, opposite or verti-cillate, are found at the base of the stem of Sigillaria, which makes it impossible to admit that Sigillaria was at first an ascending bud,� amp;c. In anynbsp;case we shall do well to withhold assent to these views of the French authors,nbsp;so long as they are unable to produce stronger proof in support of them.

Other remains resembling Stigmaria from the Devonian formation have been described under the names Cyclostigma� and Arthrostigma* butnbsp;they are only known in impressions, and are therefore of small importancenbsp;to the botanist. Cyclostigma kiltorkense, Haught. with some other formsnbsp;is abundant in the yellow Upper Devonian sandstone of Kiltorkan Hill innbsp;Ireland, and occurs also according to Heer� in the deposits of his Ursanbsp;stage (the confines of the Devonian and Carboniferous formations) in Bearnbsp;Island. According to Haughton the smooth or wrinkled surface of thenbsp;fossil is marked with small circular distant scars in regular many-memberednbsp;whorls. Heer, who had specimens from Bear Island before him, declaresnbsp;that Haughton�s drawings are bad, and figures a quincuncial position ofnbsp;the scars exactly like that of Stigmariae ; and this is found in an Irighnbsp;specimen which I saw in the Museum at Breslau, and which is figured bynbsp;F- Romer�. Other similar remains have been repeatedly described; fornbsp;example, by Schmalhausen � from the Ursa stage of Siberia, by Weiss�nbsp;(Cyclostigma hercynicum), by O. Feistmantel � (C. australe, O. Feistm.)nbsp;from the confines of the Devonian and Carboniferous formations in Newnbsp;South Wales and Queensland.

Dawson has devoted an entire plate to his genus Arthrostigma discovered in the Lower Devonian beds of Gaspe in Canada; its branched axes are striated and furrowed and beset with very irregular whorls ofnbsp;round scars, to which sharp-pointed thorn-like appendages with a broadnbsp;base are attached at right angles to the axis.

^ Williamson and Hartog (5), p. 349- nbsp;nbsp;nbsp;� Williamson and Hartog (5) p. 349-

� Haughton (1); Schimper (1), vol. iii, p. 530- nbsp;nbsp;nbsp;* Dawson (1), vol. i, p. 41 ; t. 13; Schimper

(t), vol. iii, p. 54(j. nbsp;nbsp;nbsp;5 Heer (5), vol. ii,I, p. 43 ! C n-nbsp;nbsp;nbsp;nbsp;' Romer (1), vol. i, p. 225.

� Schmalhausen (3), t. i. nbsp;nbsp;nbsp;* Weiss (3), p. i75. t- 7-nbsp;nbsp;nbsp;nbsp;quot; O- Reistmantel (1), m. Part H,

XIII.

It was long believed that there was no group of extinct palaeozoic plants in which the affinities were more distinctly recognised and determined,nbsp;than in that of the Calamarieae which we have now to consider. But thisnbsp;belief has been so far shaken at the present day, that it is not even possiblenbsp;to give such a connected account of the actual material and of the resultsnbsp;which have been obtained from its investigation, as those which have appeared in the former chapters of this work. The best plan therefore willnbsp;be, first to give a short summary of the facts and of the views entertainednbsp;respecting them, next to consider separately the different categories ofnbsp;fossil remains which have been referred to the group, and lastly to appendnbsp;a critical examination of the conclusions which have been founded uponnbsp;them. We begin with the stems and branches usually united togethernbsp;under the name Calamitae, and shall go on to the smaller leafy branchesnbsp;and to the fructifications which have been assigned to them.

Calamitae are found in enormous quantities throughout the entire series of Carboniferous deposits. They are the well-known fluted stemsnbsp;divided into members at regular intervals and often attaining colossalnbsp;dimensions, which appear in the form of impressions and casts. Theirnbsp;resemblance in habit to Equisetae is so great, that it soon came to be thenbsp;one generally insisted upon, and the comparisons with the bamboo-canenbsp;and similar stems, such as occur in the oldest authors, Steinhauer ^ fornbsp;example, were soon forgotten. As early as 1828 Brongniart ^ placed Equi-setum and Calamites side by side as equivalent genera of Equiseteae, andnbsp;in the latter genus among other forms he placed Calamites Mougeotii andnbsp;C. arenaceus, which have since that time been determined to be casts ofnbsp;the central cavities of Triassic Equisetitae, as was stated above on p. 177.nbsp;In contrast to Equisetitae, whose leaf-sheaths are often preserved in thenbsp;form of impressions, the leaves of Calamitae are unusually rare. They

are linear and not united laterally into a sheath, and will have to be described in greater detail in the sequel. In addition to the leaves large patelliform scars, the points of attachment of lateral branches, are foundnbsp;at the nodes with a different arrangement and distribution in each case.nbsp;In many instances entire branch-systems have been found in connection,nbsp;and in this way it has been ascertained that the branches often narrownbsp;and become conical at the base, as in Equisetitae. . Impressions also of

There are virtually three different states of preservation in which these Calamitae are presented to our notice. They appear most commonly as cylindrical or flattened casts, presenting the form of a broadnbsp;inner medullary cylinder, and analogous with the calamitoid casts ofnbsp;Equisetitae. They appear also in the form of surface-impressions withnbsp;the leaf-scars, to which in extremely rare cases the leaves are still attached.nbsp;Such surface-pictures occur more especially on the rind of coal on thenbsp;casts, where that is well preserved j but it is true that this is not often thenbsp;case in our collections. Lastly, they are found in a state of petrifaction,nbsp;and then usually without the rind, and containing only the vascular bundle-system or xylem-system which incloses the medullary cavity. Silicifiednbsp;specimens of this kind occur especially at Autun, Grand Croix and Chemnitz,nbsp;and are a generally distributed portion of the material contained in thenbsp;calcareous nodules of England and Westphalia. It is remarkable thatnbsp;almost all the many petrified specimens which have been examined shownbsp;the presence of a considerable mass of secondary wood traversed by primarynbsp;and secondary rays.

Further, undoubted impressions of Calamitae have been repeatedly found in immediate connection with well-characterised spike-like fructifications, which are also of frequent occurrence under other circumstances jnbsp;these fructifications present the characters of those of archegoniate plants,nbsp;sometimes even allowing spores of two kinds to be seen, and in most casesnbsp;recall mutatis mutandis even at first sight the conditions observed in Equi-setum.

On the facts thus briefly enumerated, and which must be examined more carefully later on, are founded the views which prevail among thenbsp;different authors respecting the systematic position of Calamarieae. Wenbsp;must here give a preliminary account of these views, in order to makenbsp;our further remarks intelligible.

The question seemed to the older authors to be extremely simple, so long as the petrified specimens were either not known or little regarded.nbsp;The stems and the fructifications just mentioned were considered to belongnbsp;to one another, and thus was formed the family of Calamarieae, whichnbsp;appeared to stand in the very closest relation.ship to Equisetae. Afterwards

when, in consequence of the impulse given by Brongniart the fact of the secondary growth of wood in the stems of Calamitae began to benbsp;taken into account, opinions became at once divided. Brongniart himselfnbsp;on elementary grounds, which we have already considered in the chapternbsp;on Sigillariae, was entirely opposed to the assumption of a secondary growthnbsp;in thickness in archegoniate plants, and suggested the separation of Cala-marieae into two groups, which belonging to quite different divisions ofnbsp;the vegetable kingdom were supposed to show great resemblance to onenbsp;another only in the vegetative region. He was followed on this path notnbsp;only by his pupils, Renault especially and Grand� Eury but by G�ppert �nbsp;also and more recently by Schenk One of these groups, the Calamiteae,nbsp;was to include the fructifications of archegoniate character, together withnbsp;the impressions of stems belonging to them and also a portion of the casts ;nbsp;it was supposed to belong to the cycle of affinity of Equisetinae, and tonbsp;have no secondary growth. To the other group, that of Calamodendreae,nbsp;was assigned all the petrified specimens with secondary growth and anbsp;corresponding number of impressions and Casts, and these were referred tonbsp;Gymnosperms on account of the structure of their wood. Renault� liasnbsp;recently inclined to connect them with Gnetaceae, and to look upon somenbsp;of the fossil carpoliths as their seeds.

There is another group of authors, with Schimper Williamson and more recently Stur � at their head, who hold firmly to the belief that thenbsp;remains of Calamitae all belong to one division of plants, and see in themnbsp;a group allied to Equiseteae, and distinguished from them by the introduction of secondary growth, just as Lepidodendron and Sigillaria arenbsp;distinguished from recent Lycopodiaceae.

As the occasion for this difference of opinion came from the petrified specimens, it will be well to take them first into consideration. In generalnbsp;they are nothing more than the hollow cylinder of wood deprived of thenbsp;rind, and inclosing a broad medullary tube filled with the mineralisingnbsp;matter. If the section has not passed directly through a node, it disclosesnbsp;a perfectly regular circle of wedges of wood. Each of these wedges terminates on the side of the pith in a sharply projecting primary bundle,nbsp;the transverse section of which may vary much in its form, and in the innernbsp;angle of the bundle there is usually a roundish irregularly defined lacuna,nbsp;which has often been taken for the analogue of the carinal canal of Equi-setae. The lacuna is usually bounded on the inside by a group of elementsnbsp;with rather broad lumen, and these are succeeded by any parenchyma-cellsnbsp;which still persist in the periphery of the medullary tube. In some rare

� Brongniart (2), p. 97. nbsp;nbsp;nbsp;Grand� Eury (1).nbsp;nbsp;nbsp;nbsp;� G�ppert (3).nbsp;nbsp;nbsp;nbsp;� Schenk (2),

and Zittel (1). nbsp;nbsp;nbsp;� Renault (2), vol. iv, p. 215.nbsp;nbsp;nbsp;nbsp;� Schimper (1).nbsp;nbsp;nbsp;nbsp;� Williamson (1).

cases the tissue which originally filled this lacuna is present, and then on the transverse section it is either exactly like the tissue which surrounds it,nbsp;or it consists of more thin-walled elements with broader lumina, butnbsp;between these there are often single thick-walled cells with narrowernbsp;transverse section and without regular arrangement. Schenk who hasnbsp;figured a badly-preserved specimen of this kind, explains the mass whichnbsp;fills the lacuna as bast, and the large elements which adjoin it on thenbsp;inside as the tracheides of the primary wood, so that the whole of thenbsp;secondary growth must have originated in extrafascicular cambium. Butnbsp;the original preparations, which he sent me at my request, being all exact

Fig. 39. Structure of Arthropitys. A portion of the transverse section. B fragment of a transverse section of ring of wood with the adjacent parenchyma of the pith, showing two wedges of wood, each of which has a lacuna innbsp;primary strand ; between them the primary strand is converted into closed wood. C portion of a transverse sectionnbsp;�Orm the ring of wood of an Arthropitys; the wedges of wood are separated from one another by narrow primarynbsp;^�^ys which increase rapidly in breadth towards the pith ; there is a lacuna of diminutive size in the primary bundle ofnbsp;wedge. A after Binney (1), slightly magnified. B after Weiss (5). C after Binney (1).

transverse sections, do not at all justify this explanation ; and I am still less able to declare my assent to it, since Renault^ has found none butnbsp;tracheal elements in the portion of the wedge of wood in question in thenbsp;Similar form Astromyelon, and also because the large elements regardednbsp;hy Schenk as the primary xylem-bundle have proved to be parenchymatous cells in every case, in which obliquely directed sections have madenbsp;^t possible to determine them exactly. I have had opportunity of examining specimens supplying extremely clear and indubitable proofs of thenbsp;point, especially in the collection of sections in the Botanical Department ofnbsp;Ihe British Museum. Unfortunately there are not unimportant difficulties

in the way of getting together any great number of cases of the kind. Longitudinal sections directed with a view to such minute details are precarious, and to this must be added that they are of value only where thenbsp;sculptures of the cell-walls are perfectly preserved, which is seldom thenbsp;case. But with ail this I still have no doubt but that in the lacunae or innbsp;the tissue which fills them we are dealing with the tracheal initial strand ofnbsp;the primary bundle. Apart from this portion the xylem-wedges, accordingnbsp;to the accordant testimony of linger^, G�ppert^ and Renault�, consistnbsp;essentially of rows of scalariform tracheides, and with these, according tonbsp;Renault, are several rows of pitted elements. The medullary rays will benbsp;noticed again by-and-by. In the preparations before me I find only scalariform vessels, but I have in fact seen sections in the British Museum, innbsp;which both forms were present connected by intermediate forms. Annualnbsp;rings, which might have been expected where the ring of wood is sometimesnbsp;of unusual thickness, as much as a foot thick, are never seen; the woodnbsp;seems everywhere uniform, only tangential fissures or local displacementsnbsp;through pressure, such as often occui-, might to a hasty glance have thenbsp;appearance of rings. It is this absence of annual growth, as well as thenbsp;peculiar broad bordered pits in single rows which make me suspect, asnbsp;I have already said, that the wood described by G�ppert ^ as Protopitysnbsp;Buchiana from the Culm of Glatzisch-Falkenberg in Silesia belongs to thenbsp;present group.

The wood of all Calamitae has not only the interfascicular but also numerous secondary rays. These differ considerably from one another,nbsp;but they are all strikingly distinguished from those of Coniferae, as Renault�nbsp;has pointed out, by having their elements prolonged in the direction ofnbsp;the axis of the stem, not in that of the radius, as in the latter group. Wenbsp;have no exact information as to the nature of the pitting, and indeed thenbsp;structure generally of these woods urgently requires further searchingnbsp;investigation. The interfascicular rays also show unusual multiplicitynbsp;of structure. Cotta� himself was struck by these variations in character,nbsp;and employed them to distinguish the species striata and bistriata in hisnbsp;genus Calamitea, and these were afterwards raised by G�ppert'^ to the ranknbsp;of genera, and named Calamodendron striatum and Arthropitys bistriata.nbsp;Brongniart�s name, which originally included all calamitoid stems withnbsp;secondary growth, is thus confined to a particular type of them, andnbsp;Goppert�s nomenclature was then adopted by the French school, whichnbsp;treats the two genera as members of the family of Calamodendreae. Thenbsp;two types can usually be readily distinguished even on the simply polishednbsp;surface of a section, for in Arthropitys the primary rays disappear towards

� Unger (9). nbsp;nbsp;nbsp;^ G�ppert (3), p. 179.nbsp;nbsp;nbsp;nbsp;� Renault (13).nbsp;nbsp;nbsp;nbsp;* G�ppert (12), p. 252,

t. 36 and (4), p. 229, tt, 37, 38. nbsp;nbsp;nbsp;� Renault (13).nbsp;nbsp;nbsp;nbsp;� Cotta (1).nbsp;nbsp;nbsp;nbsp;� G�ppert (3).

the outside in the secondary wood;, that is they become indistinguishable there, while in Calamodendron they retain their breadth and distinctnessnbsp;throughout. The wood of Arthropitys is nearly uniform, that of thenbsp;other genus is composed of alternating ribbon-like bands of nearly equalnbsp;breadth, some of which represent the wedges of the bundle, the others thenbsp;rays. There is a difference also in the vertical distribution of the two types.nbsp;Arthropitys is found in various horizons of the true Coal-measures fromnbsp;the base upwards, being extremely abundant in the Coal-measures ofnbsp;Lancashire, in which no trace of Calamodendron has hitherto been found.nbsp;In fact the latter genus seems to be confined to the uppermost beds of thenbsp;Carboniferous formation and to the Rothliegende, in which it has beennbsp;shown to occur associated with Arthropitys at Chemnitz and Autun, in thenbsp;Val d�Ajol and at Grand� Croix. The specimens from Grand� Croix arenbsp;black throughout; in those of Chemnitz, figured first by Cotta h the bandsnbsp;in the transverse section are alternately lighter and darker in colour, andnbsp;the whole has thus a pretty and highly characteristic appearance.

Detailed accounts of the peculiar composition of the medullary rays in Calamodendron are not frequent either in linger^, Petzholdt�, or Renault^.nbsp;According to the latter author they consist chiefly of elongated thick-wallednbsp;fibres. Either each ray consists of two fibrous laminae which are separatednbsp;by an intervening band of parenchyma and adjoin the bundles, or of fivenbsp;Successive laminae, the lateral and central laminae being composed of fibres,nbsp;the two between them of parenchyma. The account given by Unger, whonbsp;examined the specimens from Chemnitz only, while Renault relies on thosenbsp;from Autun and Grand� Croix, is somewhat different. He says that thenbsp;�Wood consists of alternating bands of different structure. Both these bandsnbsp;contain ordinary parenchymatous medullary rays which may be formed ofnbsp;several rows of cells, but in some of them the mass of the wood consists ofnbsp;scalariform vessels, in the others entirely of parenchyma-cells of narrownbsp;diameter and with strongly thickened walls. But the figure of a tangentialnbsp;section given in Petzholdt � does not answer to this description, but agreesnbsp;rather with Renault�s account. In specimens from Grand� Croix I find thenbsp;structure to correspond exactly with Renault�s description. A specimennbsp;from Chemnitz on the other hand shows an entirely different structure, andnbsp;Agrees to some extent with Unger�s description. In the former the primarynbsp;ray consists of two lateral laminae of fibres with a narrow band of parenchyma interposed between them ; in the latter of a compact fibrous, not, asnbsp;^nger supposes, a parenchymatous mass, which encloses numerous rays ofnbsp;rrioderate depth and varying breadth. We should in the latter case in factnbsp;be more correct if we spoke of an interfascicular wood rather than of a

primary ray. The lacunae in the tissue, expressly mentioned by Renault, are also described by Unger�^. In Petzholdt�s figure these lacunae alternatenbsp;with other broader passages, which are in all cases placed where the primarynbsp;ray passes into the pith. They appear to answer rather to incidental gaps,nbsp;fissures in the tissue, such as are found in this situation in the wood ofnbsp;many Calamitae. It is plain from the above incoherent and imperfectnbsp;statements how necessary it would be to procure a connected examinationnbsp;of all the material stored up in the Museums.

The forms grouped together under the name Arthropitys also show many variations in respect to the behaviour of their primary rays (Fig. 39),nbsp;and these variations may hereafter give rise to the formation of new genera.nbsp;But at present little has been done in this direction; a more extended anatomical investigation of these woods has still to be made. I must thereforenbsp;content myself with a reference to the few figures of transverse sections ofnbsp;Arthropitys which the literature supplies. In all of these we find that thenbsp;primary rays pi'oject distinctly where they unite with the pith, and give itnbsp;a stellate toothed outline, and that towards the outside they either graduallynbsp;or quite suddenly become indistinct, their tissue approximating in characternbsp;to that of the wedges of wood. In the former case this appears to benbsp;brought about either by the formation of numerous narrow interfascicularnbsp;strands, an example of which will be found in Williamson or by gradualnbsp;increase in breadth of the wedges of wood at the expense of the raysnbsp;(Fig. 39 C), as is shown in Williamson�s� and Weiss�^ figures. On thenbsp;other hand there are cases in which the entire tissue of the medullary raysnbsp;in the secondary growth assumes the character of wood after the mannernbsp;of some herbaceous plants, Labiatae for example and Scrophulariaceaenbsp;(Fig. 39 B), as appears from figures in Weiss� and Williamson�; but thenbsp;character of the wood, almost unknown, will have to be further inquirednbsp;into. How far all the differences here indicated are sharply distinguishablenbsp;from one another, or are connected together by intermediate forms, thenbsp;meagre material afforded by the literature in the absence of personal investigations of any extent does not enable me to determine.

Archaeocalamites (Bornia) radiatus also, which will have to be considered more in detail presently, shows similar structure of the wood, as appears especially from Renault�s^ recent descriptions. He has foundnbsp;portions of silicified stems with the characteristic stidation in the porphyry-tuffs of Enost north of Autun. A broad pith is surrounded by a closednbsp;ring of wood, and the well-known lacunae are found in the primary bundles.nbsp;The tracheides bear three rows of bordered pits, and the cells of the

' Petzholdt (1), t. 8, f. 6. nbsp;nbsp;nbsp;' Williamson (1), I, t. 25, ff. 16, 17.nbsp;nbsp;nbsp;nbsp;� Williamson (1),

I, t. 27, f. 26. nbsp;nbsp;nbsp;* Weiss (5), p. 10, ff. I, 2.nbsp;nbsp;nbsp;nbsp;* Weiss (5), p. 10, f. 3.nbsp;nbsp;nbsp;nbsp;� Williamson

medullary rays, which though formed most of them of only one row of cells are still of some depth, are elongated in the direction of the axis ofnbsp;the stem, as in the woods which we have been considering. These remainsnbsp;are named Bornia enosti, Ren. Richter^ had previously noticed thesenbsp;fossils, but his account of them is not intelligible; G�ppert also had discovered remains undoubtedly belonging to this plant in the Carboniferousnbsp;limestone of Glatzisch-Falkenberg, and his remarks upon them are of anbsp;better kind ; his specimens ^ are it is true very fragmentary, but they shownbsp;single shallow medullary rays of one row of cells, and treatment of thenbsp;sections with acids also discloses tracheides with bordered pits broader thannbsp;fong, and irregularly disposed in several rows.

The rind is only rarely preserved in its connection with the wood, and its structure appears from the statements of authors to be very variable.nbsp;The structure of the rind in the genus Astromyelon will be noticed againnbsp;presently. Renault^ found that the rind of Arthropitys medullata wasnbsp;composed of compact uniform parenchyma, and contained groups ofnbsp;resin-canals (?) in front of the wedges of wood ; and that in A. bistriatanbsp;and A. lineata there was Dictyoxylon-structure also in the outer portion ofnbsp;the rind,�the well-known reticulated system of radial laterally anastomosingnbsp;strands of sderenchyma. The only preparation before me in which thenbsp;rind is preserved, and which is from the Oldham nodules, presents to somenbsp;extent the conditions of the species first mentioned. A good specimen ofnbsp;the kind is figured in Hick and Cash'^; it shows the soft bast which isnbsp;hounded on the outside by a layer of thick-walled cells. The primary rindnbsp;consists of an inner portion with delicate cells and with many fissures causednbsp;hy the tearing of the tissue, and of an outer layer, the elements of which havenbsp;thicker walls and frequently contain coal. Unfortunately no longitudinalnbsp;sections of this specimen have been published.

In examining the wood in these plants it is not an uncommon thing to come upon preparations which have struck the region of a node. I possessnbsp;�uch a preparation with the beginnings of four branches proceeding from thenbsp;node. The presence of the nodes can sometimes be recognised even fromnbsp;without, if weathering or planes of fracture running in a favourable directionnbsp;have laid bare the outer surface of the wood stripped of the rind, or thenbsp;boundary line between it and the pith. Sturquot;*, with a right perception ofnbsp;the fact that it is only by attention to these points that we can have anynbsp;proof that certain casts of Calamitae belong to our woody bodies�a proof,nbsp;on which rests the course of exposition here adopted�has been careful tonbsp;collect all the cases of this kind'known to him, and to discuss them fully.nbsp;His finest specimen� is represented in Fig. 40. It is a well-preserved

example of Arthropitys bistriata from Chemnitz, in the museum of the Provincial Geological Institution at Leipsic, in which the medullary tube isnbsp;not filled up, but allows the inner boundary of the woody body to be seennbsp;in all its details. Four nodes are visible as transverse projecting lines; thenbsp;short internodes show regular longitudinal striation, in which the ridgesnbsp;correspond to the bundles of the medullary sheath, and the furrows to thenbsp;primary rays. By means of squeezes with gutta-percha Stur has obtainednbsp;the picture of the cast of the specimen, which answers absolutely to an

ordinary cast of Calamitae, and shows the lines of the nodes as transverse furrows. The bands of the medullary rays now appear of course as ribs,nbsp;the bundles of the medullary sheath as furrows on the surface. Almost asnbsp;beautiful is the specimen represented on another table an Arthropitysnbsp;from the Rothliegende of Neu-Paka in the Museum of the Imperial Nationalnbsp;Institution. A portion of the quartz which filled the medullary tube camenbsp;away from the two halves, and the surface of the cast thus preserved presented the picture of one of the Calamitae with all the characteristic details

of its surface. Exactly similar pictures result when the outer surface of the woody body deprived of the rind is disclosed to view, as is the case withnbsp;a piece of petrified wood of Arthropitys from St. Berain (Saone et Loire) innbsp;my possession. Unfortunately this piece of wood, which is as thick as annbsp;arm, though it shows the wedges on the face of the section, is too badlynbsp;preserved for microscopical examination 1. I have verified this specimennbsp;by comparison with two others from the calcareous nodules of Langendreernbsp;and Oldham, the best of which is kept in the Museum at Strassburg. Butnbsp;in these, in contrast with the cast, the ridges on the surface, which is markednbsp;by slightly sinuous furrows, answer to the somewhat convex outer faces ofnbsp;the wedges of wood, the furrows to the rays. The Strassburg specimennbsp;shows a nodal line tolerably distinctly as a transverse swelling. A still finernbsp;piece from Oldham also showing a node may be seen in Binney^.

Williamson�, Binney^and Stur� have published longitudinal sections through these nodes. Williamson�s first figure is taken from a specimennbsp;tvith a weakly developed woody body, elongated internodes, and the rindnbsp;preserved ; that of Stur, determined as Calamites approximatus, has quitenbsp;short internodes and numerous equidistant nodes ; its woody body is ofnbsp;considerable thickness. A diaphragm stretches across the medullary cavitynbsp;at each node. This diaphragm is a parenchymatous structure of no slightnbsp;thickness, and in Stur�s specimen it maintains this thickness in all parts, butnbsp;in Williamson�s it fines down towards the centre into a thin lamina. In anbsp;similar preparation in the collection of sections in the Botanical departmentnbsp;of the British Museum, a foliar bundle may be seen in exact longitudinalnbsp;section on the line of the diaphragm running towards the outside. But thenbsp;tangential sections are much more important and instructive when they passnbsp;through a node, as happens in some of Williamson�s figures�. From thenbsp;two figures especially in the first of the monographs, one of which is herenbsp;�quot;eproduced in Fig. 41 A, and in which the sections have encountered thenbsp;Woody body in the neighbourhood of the pith where the primary rays arenbsp;broad and evident, we see that the position of the secondary wedges of woodnbsp;directly follows the original primary course of the strands. This course agreesnbsp;essentially with that of recent Equisetae. Each bundle passes downwardsnbsp;through an internode, and then forks and unites by its limbs with the adjoining bundles in the node next below, which thus shows the well-known brokennbsp;zigzagged commissural-strand. In this process the descending bifurcatingnbsp;strands are often split up in such a manner as to enclose a wedge-shaped spacenbsp;With two pointed ends, which resembles a medullary ray and is filled withnbsp;parenchyma. And other sections in the ninth monograph, unfortunately of too

Grand� Eviry (1), p. 286. nbsp;nbsp;nbsp;^ Binney (1), I, t. 3, f. i.nbsp;nbsp;nbsp;nbsp;� Williamson (1), I, t. 24,

; nbsp;nbsp;nbsp;2�. f- 15-nbsp;nbsp;nbsp;nbsp;* Binney (1), I, t. 3, f- 3-nbsp;nbsp;nbsp;nbsp;'nbsp;nbsp;nbsp;nbsp;(8), p. 459, f. 14.

1 liamson (11, i, t. 23, f. 2 ; t. 26, ff. 22, 25 ; ix, t, 20, ff. 23, 24, 29 ; t. 21, ff. 26, 28.

small extent, show that still greater deviations occur in the nodes (Fig. 41 B), and that by repeated formation of intermediate cauline strands from the uppernbsp;and possibly from the lower extremities of the primary rays, other ellipticalnbsp;portions of the kind bounded by loops of wood may be cut off. Such complications, unknown as yet in the nodal zone of Equisetae, are extremelynbsp;common in Angiosperms, in which according to present observations theynbsp;cannot at all be referred to distinct types, but seem to be absolutely irregular.nbsp;In many cases, not indeed necessarily in all, these small meshes are traversednbsp;by bundle-strands passing outwards (leaf-traces or traces of adventitiousnbsp;roots), the transverse sections of which lie in the middle of their parenchyma ;nbsp;this has been already recognised and described by Williamson. The lateralnbsp;shoots also, where they traverse the wood, are seen to be surrounded bynbsp;similar strand loops Where the primary rays of Williamson�s lower internode end above towards the zigzag strand of the node, the tangentialnbsp;section very commonly shows in each of them a roundish or ovoid empty

Fig. 41. Tangential section through the wood of Arthropitys, showing the irregularities of its course in the node as mentioned in the text; at a the so-called infranodal canals. In some of the small rhombic nodal medullary raysnbsp;are transverse sections of vascular bundle-strands running towards the outside and indicated by points. Afternbsp;Williamson (1).

space with tolerably distinct boundary lines (Fig. 41), which, as appears from some preparations in Williamson�s collection, passes from within outwards through the whole length of the medullary ray^. These peculiarnbsp;canals, called by Williamson infranodal canals, are proved by other sectionsnbsp;in the same collection to be caused by the disappearance of a strip of parenchyma, which differs a little in character from the surrounding parenchymanbsp;of the ray. Then in many cases the terminal segment which conceals thenbsp;canal is sepai'ated by formation of anastomoses from the internodal portionnbsp;of the ray, and is changed into one of the pi�eviously mentioned nodalnbsp;lacunae. We should accordingly have to distinguish two kinds of thesenbsp;nodal rays, one containing the infranodal canals arranged in a regular circlenbsp;but no bundle-strands, the other, with much less regularity of developmentnbsp;in number and position, inclosing the bases of the branches, and in some casesnbsp;allowing other casual trace-bundles to pass through them. Williamsonnbsp;places the latter exactly on the line of the node, the former beneath it.

Further, the course of the strands in Calamarieae appears to deviate in not unimportant points from that hitherto assigned to Equisetae, as maynbsp;be gathered from certain anomalies in the sculpture of the casts which mustnbsp;be considered by-and-by. On this point there is scarcely anything to benbsp;said in the absence of investigations into the details of the subject. I maynbsp;rnention however that I have seen a section in the British Museum, in thenbsp;node of which several adjacent xylem-strands of the successive internodesnbsp;instead of alternating lay exactly one on another. The upper trace-strandnbsp;divides into two limbs, which diverging first of all and anastomosing laterallynbsp;with neighbouring strands, afterwards converge again and unite to formnbsp;the lower trace-strand. In the mesh thus formed, which breaks the directnbsp;Continuity of the strands, there was always to be seen the transverse sectionnbsp;of an emerging bundle, or at least the trace of the particular node.

Lastly, before going on to speak of casts of Calamitae it will be necessary lo notice the genus Astromyelon, about which very different views havenbsp;been expressed in recent times. This genus was founded by Williamson ^nbsp;on remains which showed in their transverse sections the characters ofnbsp;�Arthropitys, with the exception of the intercellular cavity in the primarynbsp;bundle; and in it he now places several of th� transverse sections ^ whichnbsp;be had himself before named Calamites, and makes its most importantnbsp;character to be the absence of stem-nodes bearing whorls. It is also saidnbsp;Ibat the parenchyma of the medullary cylinder is usually though notnbsp;invariably preserved. Meantime remains of peculiar stems with spongynbsp;lacunose rind and with the medullary cylinder filled with parenchyma werenbsp;discovered by Hick and Cash� in Halifax, and were described as Myrio-Pbylloides Williamsonis; but they were subsequently re-examined bynbsp;Williamson^ and united with Astromyelon, the peculiar feature of thenbsp;quot;�ind being added to the characters of the genus. However, Hick and Cash �nbsp;have at once raised objections to this identification. That the transversenbsp;Section of the wood-body of Myriophylloides does really show a picturenbsp;different in not unimportant points from that of Arthropitys, I have beennbsp;^ble to satisfy myself by inspection of sections obtained from Mr. Cashnbsp;bimself�; but it is useless to discuss the question till we have more information respecting the nature of the longitudinal sections.

The characteristic structure of the rind depends on the presence of a Simple girdle of wide intercellular spaces in the middle of the rind, whichnbsp;become broader and wedge-shaped towards the outside, and which, evidentlynbsp;schizogenetic in origin, are separated from one another by narrow radialnbsp;plates of tissue from two to a few cells in breadth. But a structure of

this kind, as we know, and as Hick and Cash ^ have well shown, may make its appearance in a similar manner in plants very far removed from onenbsp;another, if only they have certain adaptations in common, such as growingnbsp;in water or in wet places ; it can hardly therefore be employed to determinenbsp;a genus or a group, or, if so, only in peculiar circumstances.

Further, Renault^ has described several species which he assigns to Astromyelon, and has figured three of them. Astromyelon augustodunense,'nbsp;Ren., A. dadoxylinum, Ren. and A. nodosum, Ren., on the three plates of hisnbsp;work. He too, like Williamson, insists especially on the absence of nodes,nbsp;and remarks that the structure of the wood shows the greatest resemblancenbsp;to that of Arthropitys, being essentially distinguished from it only bynbsp;the presence of the �bois centrip�te,� which is closely connected with the � boisnbsp;centrifuge� and is surrounded by it. From this remark, and also from thenbsp;circumstance that Renault cites in this connection Schenk�s^ figure noticednbsp;above, and will not allow it to be an Arthropitys, I perceive that the � boisnbsp;centrip�te� does not mean here the entire primary bundle, as it usually doesnbsp;elsewhere, but only its initial strand, and further that on the transversenbsp;section at least there is no difference to be observed between Renault�snbsp;Astromyelon and his Arthropitys. We saw above that in the same sectionnbsp;the initial strand may be preserved in some bundles, and may be replacednbsp;by a lacuna in others. The absence of nodes would then be the onlynbsp;remaining difference. It is not for me to determine what is the true accountnbsp;of the matter, for I have had no opportunity of properly studying thenbsp;remains in question. It is to be hoped that Renault himself will soonnbsp;give us some further explanation. The structure of the rind is only knownnbsp;in one of the three species described by him, Astromyelon augustodunenseknbsp;There it is entirely parenchymatous, and the inner portion which surrounds the ring of wood is traversed by groups of dark-coloured cells,nbsp;which lie in front of the wedges of wood, and are explained as ' canaux � ornbsp;� cellules a gomme.� The intercellular spaces of the middle portion ofnbsp;the rind are only of moderate breadth, and are separated from one anothernbsp;by thick plates of tissue consisting of several layers of cells.

It is evident from what has now been said that nothing at all certain can be stated at present respecting Astromyelon, and that it is possible thatnbsp;different plant-forms have been united under this name. The structurenbsp;of the wood affords not the slightest ground for comparing this genus withnbsp;Marsilea, as is done by Williamson �; if there are points of resemblance, andnbsp;I am myself unable to find them, they must be of purely external character.nbsp;Renault� even has not ventured to draw any conclusion from the circumstance that these remains are often associated at Grand� Croix with

* Hick and Cash (1), p. 91. nbsp;nbsp;nbsp;' Renault (13).nbsp;nbsp;nbsp;nbsp;f Zittel (1), p. 337.

(13), t. 7, ff. I, 3. nbsp;nbsp;nbsp;' Williamson (1), xii.nbsp;nbsp;nbsp;nbsp;' Renault (13).

Stephanospermum, Polylophospermum and Gnetopsis elliptica; but he has now^ come to the conclusion that all the forms of Astromyelon are rootsnbsp;of Calamodendron and Arthropitys, and that Astromyelon dadoxylinumnbsp;belongs to Calamodendron and A. augustodunense to Arthropitys. Innbsp;face of the evident stem-structure shown by his own figures, and whichnbsp;it is scarcely possible to call in question, the botanist finds it difficult tonbsp;understand how such a view is possible. Its author himself says that thenbsp;general root-character can only be seen on young branches, and the reasonnbsp;which he proceeds to give for his opinion appears, if I rightly understand it,nbsp;to rest on an assumption of the boldest kind. It would require some timenbsp;to examine into this assumption, and I am the less inclined to do so,nbsp;because it is before us at present only in the fprm of a sketch suited to thenbsp;preliminary communication in which it is contained, and it is thereforenbsp;hardly possible to avoid misunderstandings. �

The larger portion of the casts, which have long since been known by the general name of Calamitae, belongs, as may be gathered from thenbsp;previous remarks, in part at least to the woody bodies known as Calamo-dendreae. Another portion according to the French authors comes fromnbsp;hypothetical plants resembling Equisetum, and having no growth in thickness. The question at once arises whether it is possible to separate thenbsp;Casts of the two kinds and how this is to be done, a question which engagednbsp;the attention of Brongniart ^ himself, but which has been studied more particularly and in the widest extent by Grand� Eury^ and RenaultGrand�nbsp;Eury, after consideration of all the circumstances, and relying especiallynbsp;nn his mining experience and on the mode of occurrence of the fossils,nbsp;answers the question in the affirmative, showing that there are firstly, castsnbsp;of Calamitae with a very thick rind of coal without striae on the surface,nbsp;and secondly, those in which the rind is no thicker than paper, so thatnbsp;Ihe striation on the cast appears even on the outside, though not so plainly.nbsp;The two types, still in the erect position, occur equally abundantly in thenbsp;quarries in the district of St. Etienne, of which he gives a sketch�. Thenbsp;Specimens of the first kind, Calamodendreae, are constantly found singly,nbsp;^ith their narrowed and fusiform extremities passing vertically throughnbsp;ffie beds, and giving off from the nodes close whorls of long simplenbsp;descending roots�. Those of the other kind on the contrary�^ occur innbsp;groups and converge below, and .spring from erect or horizontal rhizomes;nbsp;fheir conical base, either attached directly to the rhizome which bears themnbsp;Or narrowed into a long thin thread-like basal portion, is always� bent roundnbsp;3- little to one side in the manner described above in the case of the bases of

Renault (14). nbsp;nbsp;nbsp;2 Brongniart (2).nbsp;nbsp;nbsp;nbsp;* Grand� Eury (1), pp. n, 282.nbsp;nbsp;nbsp;nbsp;� Renault (2),

�gt; P- 157. nbsp;nbsp;nbsp;� Grand� Eury (1), t. 34.nbsp;nbsp;nbsp;nbsp;� Grand� Eury (1), t. 31; Bindley and

�ton (1), Yol. ii, tt. ^8, 79, Grand� Eury (1), tt. 1-3. nbsp;nbsp;nbsp;* Grand� Eury (1), p. 15, t. I, f. I.

the casts of Equisetitae, and illustrated also by a figiire in the text of one of Dawson�s publications�^. The roots which spring from the nodes spreadnbsp;at right angles into the adjoining rock. A similar but vertical narrowingnbsp;is said to occur also in the much rarer branch-bearing upper extremities,nbsp;as for example in Calamites Cistii^. From his observations Grand' Eurynbsp;classes the following from among the better-known species with his genusnbsp;Calamites :�� Calamites Suckowii, Brongn., C. Cistii, Brongn., C. ramosus,nbsp;Artis, and C. cannaeformis, Schloth.� On the other hand he claimsnbsp;Calamites cruciatus, Stbg as a cast of Calamodendron, to which according tonbsp;'Weiss�� determination certain forms with a very thin rind of coal (Calamitesnbsp;multiramis^) also belong. I regret that I have never as yet had an opportunity of making myself acquainted with these differences on the spot,nbsp;which, as may be imagined, cannot be demonstrated at all or only verynbsp;imperfectly in a Museum. I once indeed saw in the Museum in Paris anbsp;large basal portion of Calamodendron, which was intended to be a standardnbsp;specimen, but it gave me no clear picture. On a second visit I soughtnbsp;for it in vain in its former position.

The casts of Calamitae, in the widest acceptation of the term, have been very recently made the objects of searching investigation by Stur� andnbsp;Weiss Some details of their external sculpture, which were not noticednbsp;in our previous summary account of them, must now be taken into consideration in connection with the exhaustive treatment which they havenbsp;received at the hands of these authors.

By far the larger number of the specimens in the collections are cylindrical pieces of casts or moulds broken off at both ends. This conditionnbsp;causes a difficulty in determining the upper and lower extremities. Thenbsp;pieces with short internodes and narrowed into a conical form at one end,nbsp;which are also far from rare, are generally believed to answer to the basesnbsp;of erect shoots ; the grounds for this belief are the facts observed in Equise-tites, and the circumstance already mentioned that they are sometimes foundnbsp;in actual connection with the stem which bears them�. If, indeed, uppernbsp;extremities of a similar kind were to occur, as Grand� Eury affirms that theynbsp;do, some caution would be necessary in this respect. Such an extremitynbsp;might be present for example in the lateral branch of Calamites ramifernbsp;figured in Stur�. Longer portions of the branch-system with the parts innbsp;attachment are much less common ; Weiss has figured a certain number ofnbsp;them ; in these specimens the upper and lower ends can generally be determined from the direction of the lateral branches. But these branches are ofnbsp;two kinds. The one kind has been already described; the others on thenbsp;contrary are cylindrical and do not narrow at the base, but are attached by

� Dawson (13), p. 195. nbsp;nbsp;nbsp;� Grand� Eury (1), t. 2, f. i.nbsp;nbsp;nbsp;nbsp;^ Weiss (5).nbsp;nbsp;nbsp;nbsp;* Grand�

Eury (1), t. 10, f. 2 and t 12. nbsp;nbsp;nbsp;^ Stur (5).nbsp;nbsp;nbsp;nbsp;� Weiss (5).nbsp;nbsp;nbsp;nbsp;Weiss (5), t. 2 ; t. 3,

f. 2 ; t. 4, f. I, and Williamson (1), IX, t. 21, f. 30. nbsp;nbsp;nbsp;� Stur (5), p, 156, f. ly.

a broad base to the node which bears them ; many examples of these branches will be found in Weiss Sometimes both kinds are observed onnbsp;the same piece. Where conically narrowed branches are seen in impressionsnbsp;of stems, there are also present almost invariably long usually simple ribbonlike stripes springing from the nodes which bear the branches and from othernbsp;nodes also, and often crowded together in tufts, which Weiss rightly takesnbsp;for impressions of rootsSuch specimens must therefore be supposed tonbsp;belong to the subterranean stem. The branches with narrowed conicalnbsp;base which spring from it may then be regarded with great probability asnbsp;the ascending foliage-shoots, the others as branches of the rhizome withnbsp;horizontal growth. And it may be fuilher assumed, and not withoutnbsp;reason, that fragments which are without roots, but have cylindrical lateralnbsp;branches not narrowed at the base, arise from the aerial leafy portions ofnbsp;the plant. Their being I'arer than the other kind is readily understood, ifnbsp;We reflect that their position in the ground is much less favourable to theirnbsp;breaking up into separate pieces. Weiss� has given fine examples of thesenbsp;branches, and Stur^ likewise.

It has already been stated that the casts of Calamites are striated longitudinally, the broad convex ribs answering to the medullary rays, thenbsp;usually narrow acute-angled furrows to the bundles of the medullary sheath.nbsp;While the striation alternates in the successive internodes, the brokennbsp;zigzag nodal line is formed in the node and always appears as a deeplynbsp;incised furrow. This is due to the preservation of the nodal diaphragms.nbsp;It may however be assumed that these were very generally broken throughnbsp;in the inner central portion in the process of making the casts, for thenbsp;I'ogular and perfect forrhation of so many connected internodes could notnbsp;otherwise be explained, and the close union of the separate internodalnbsp;members, which never have gaps between them, would be impossible,nbsp;f^eviations also from the regular alternation in the nodes are verynbsp;commonly to be seen at certain spots in the casts or extending overnbsp;longer distances, so that the ribs of successive internodes coincide. Thisnbsp;is occasionally observed in almost all Calamitae; Stur� has discussed itnbsp;Particularly in the case of his Calamites ostraviensis; in 'one form,nbsp;Archaeocalamites radiatus, it is of regular occurrence, the non-alternationnbsp;uf the ribs in the node being characteristic of the species.

Where the preservation is good the nodal line is accompanied on both sides by small roundish or ovoid prominences rising above the surfacenbsp;uf the cast. They stand in all cases on the back of the broad ribs whichnbsp;answer to the medullary rays, sometimes exactly in the middle, sometimesnbsp;also on one side, and nearer to the one adjoining furrow than to thenbsp;other. A small knob of this kind is usually found at the extremity of

every rib ; but Stur says that where the preservation was more than usually good, he has found two of them one above the other on the extremity ofnbsp;the rib on the one side of the node. They sometimes appear in the formnbsp;of small attached cylinders of regular form \ from which the usual state ofnbsp;preservation as produced by pressure can be readily deduced.

In by far the greater number of cases the two rows of small knobs are not preserved with equal distinctness ; very often one only can be clearlynbsp;seen, the other being imperceptible or only just indicated. If now wenbsp;would know whether the position of the more distinct line of knobs is anbsp;fixed one, or whether sometimes one sometimes the other line may benbsp;more prominent, we mu.st for the reasons given above confine ourselvesnbsp;entirely to the examination of branched specimens in which the directionnbsp;of growth is absolutely known. The theoretical considerations which havenbsp;determined the views of authors must be reserved for future notice. I havenbsp;examined all the figures of the kind with which I am acquainted, and havenbsp;found that in almost all cases the more apparent line of knobs correspondsnbsp;to the upper end of the lower internode, and this agrees with the directionnbsp;usually assigned to the fragments of stems of Calamitae and adopted also bynbsp;Weiss. In Stur�s figure^ only I find the opposite arrangement; both linesnbsp;are present, but the line at the lower end of the upper internode is muchnbsp;the more prominent. As there is no reason whatever for doubting thenbsp;exactness of this very excellent figure, I conclude that no absolute rule cannbsp;be laid down for the position of the stronger line of knobs, but that in casenbsp;of doubt Weiss� view is to be preferred as the more probable to the oppositenbsp;view represented by Brongniart and Stur.

Brongniart � originally attempted a morphological explanation of these small knots, and Stur ^ has recently turned his attention to the same subject.nbsp;Stur takes his stand, and rightly, on the comparison with the similar coursenbsp;of the strand in Equisetum; but at the same time he falls into a seriousnbsp;error which affects all his further conclusions, and unfortunately makesnbsp;them in my judgment entirely worthless from the botanical point of view.nbsp;It is an axiom with him, that the small protuberances correspond to thenbsp;points of attachment of leaves, buds and roots, and are therefore directnbsp;indications on the cast of the respective positions of these organs. Butnbsp;there are various objections to this view. It is obvious that projections onnbsp;the cast of a medullary cylinder can only arise where there are correspondingnbsp;depressions in the organic substance immediately surrounding it. Hencenbsp;if there has been no disappearance of tissue in the environment to cause anbsp;depression of the kind, the emergence of the vascular bundle in the directionnbsp;of the lateral members cannot of itself leave any trace behind it on the cast.

There is no sufficient ground therefore for Stur�s ^ assertion, that the presence of this character on an otherwise questionable specimen is quite sufficientnbsp;to place it with perfect certainty in the class of Equisetaceae. Even if wenbsp;accept Stur�s conception of the protubei'ances, since according to Janczewski�snbsp;researches branch and root spring from a common primoi'dium, there wouldnbsp;not be three, but only two alternating rows of small knobs on the cast of the

must be the most conspicuous objects on the nodes of leafy stems, Stur endeavours to show that the most prominent row of knobs belongs to thenbsp;leaves; and this row must be the uppermost if the comparison with Equi-setum is to be maintained. This is the reason why Stur, in opposition tonbsp;the current view, which rests, as has been shown above, on weighty arguments, inclines to determine the direction of the stems in Calamitae in suchnbsp;a manner that the most conspicuous, often the only recognisable, line ofnbsp;knobs comes uppermost. But, as Weiss ^ rightly urges, this would meannbsp;the insertion of the leaves on the base of the internode lying next abovenbsp;the node. There is no need to give further proof that such an insertion isnbsp;irot probable. But the other mode of conceiving the direction of the stemsnbsp;results in the same improbability; for in that case, since the commissure ofnbsp;the bundles must be situated in the node itself, the foliar bundles mustnbsp;'originate beneath it and in a very strange position, and the comparison withnbsp;Equisetum, in which each trace is the continuation of an ascending strandnbsp;of the lower internode, could scarcely be maintained. But I have satisfiednbsp;Oiyself from the radial section in the British Museum mentioned on p. 303,nbsp;Ikat the leaf-trace does in fact pass outwards exactly at the level of the node.

Further, the examination of Equisetum supplies no reason for assuming considerable differences in height between the points of departure of thenbsp;traces. For these appear first on the sui'face of the stem in consequence ofnbsp;the diverging course of the members ; their points of origin, alternating withnbsp;one another, are nearly at the same height, so that they can be encounterednbsp;10 one and the same transverse section. Hence the points correspondingnbsp;to the points of departure of the traces would probably be found on a castnbsp;of the pith of Equisetum in a single circle only. Lastly, Weiss � has broughtnbsp;forward yet another weighty consideration. This is founded on the ex-^niination of the mould of a Calamites from the Museum at Halle, whichnbsp;wdl have to be noticed again presently, in which the ribbing of the woodnbsp;and the surface with the leaves can be seen together. In this specimen fromnbsp;SIX to seven leaves have dropped off at regular distances from one another onnbsp;the nodal line over a breadth of twenty millimetres, but there are also fourteen

ribs with their knobs. Since the regularity of the arrangement appears to exclude the supposition that half the leaves have dropped off, Weiss concludes that there was only one leaf to every two ribs. But in that case thenbsp;leaf-traces would be twice as many as the leaves. This would necessarilynbsp;imply that the course of the strands was more complicated than we are innbsp;the habit of supposing; and this may prove to have been the case in certainnbsp;groups of Calamitae, for the specimen in question belongs to the Calamitinaenbsp;which we shall shortly have to consider.

In contrast to all these difficulties the prominences under discussion become readily intelligible, if with Williamson we see in them the traces ofnbsp;the small medullary rays of the node, and also the substance filling the so-called infranodal canals mentioned above, which, as that author has shown,nbsp;remain parenchymatous all through the life of the plant, and are nevernbsp;traversed by interfascicular strands of later formation, as is the case withnbsp;the primary rays of the internodes. The differences also in the mode ofnbsp;development of the prominences can on this view be sufficiently explained.nbsp;For if only a small portion of tissue has disappeared on their inner border,nbsp;then they present only flat swellings ; if more is gone and the matter fillingnbsp;the canals is fine enough to follow such narrow passages, then the smallnbsp;sharply defined cylinders are produced, to which Weiss has called attention.nbsp;Lastly, the case of most complete filling is exemplified in specimens suchnbsp;as those figured by Williamson in connection with which Weiss� ^ remarksnbsp;should be consulted. A cylindrical cavity contains the narrowed conicalnbsp;extremity of a cast of Calamites, from which thin rods of stone arrangednbsp;in a whorl, and spreading like the spokes of a wheel, stretch to the outernbsp;wall which bounds the cavity. These rods answer to the substance whichnbsp;filled the canals and exactly occupy their place; there is no reason fornbsp;regarding them with Stur as roots. The surrounding mass of wood wasnbsp;converted into coal, which has for the most part disappeared, though tracesnbsp;of it are still attached to the wall of the cavity. Since the entire cavity isnbsp;inside a cast which is striated like a Calamites, we can only suppose thatnbsp;the base of the particular branch was deposited in the medullary tube of anbsp;broader portion of a Calamites, and in this position was inclosed in the massnbsp;of mineral matter with which the latter became filled. If this suppositionnbsp;is correct, it confirms also Williamson�s view as to the direction of thenbsp;pieces of wood of Calamitae, which coincides with that which Weiss maintains in respect to the casts. For the disappearance of much tissue in thenbsp;infranodal canals will necessarily cause the formation of the more prominentnbsp;row of knobs ; weaker prominences on the cast will answer to the uppernbsp;medullary rays of the nodes filled with a less delicate parenchyma. Inbsp;should even conjecture that the rays which lie exactly on the level of the

node and give passage to the traces, will usually leave no knobs behind them on the cast, but that the weak protuberances of the upper internode indicatenbsp;the lower extremities of its primary rays. In that case the points of emergence of the vascular bundles would be in the middle between the two rowsnbsp;of knobs, and this would agree well with the description given on page 303.

The essential points in all these relations have been correctly recognised and explained by Williamson. But while the whole formation appears tonbsp;me to rest upon the more or less complete filling up of cavities or depressions caused simply by unequal maceration, he inclines to see in themnbsp;characteristic relations of organisation, the importance of which to thenbsp;plant has yet to be more fully explained. And though he has since ^ fullynbsp;recognised the fact that the lateral branches, the roots and the transversenbsp;sections of the trace-bundles appear in the small medullary rays of itsnbsp;upper circle, he still thinks that the canals in the rays of the lower seriesnbsp;must have had an important function to perform ; otherwise they would notnbsp;have remained unchanged throughout the entire thickness of the secondarynbsp;growth, for this is never the case to the same extent with the primary raysnbsp;of the internodes.

All that has hitherto been advanced may serve at least to show how difficult it is even in the case of normal ordinary structure to explain thenbsp;mutual relations of the wood and casts of our Calamitae, as we have themnbsp;separated from one another; and that attempts at similar explanationsnbsp;where the cases are anomalous must be hopeless from the first, so long asnbsp;We have no greater number of investigations into their anatomy to assistnbsp;us. But at present I only know of one tangential preparation of the kind,nbsp;which is preserved in the British Museum and was noticed above on pagenbsp;305'; my examination of it, though only cursory, led me to the resultsnbsp;there indicated. Nothing would be gained by a minute consideration ofnbsp;the constructions which Stur has obtained from the position of the nodalnbsp;prominences ; it will be sufficient to notice briefly his main results. Furthernbsp;information will be found in his publications The trace-scheme which henbsp;gives for the positions in ordinary Calamitae, in which there is no alternation,nbsp;. B Bnbsp;nbsp;nbsp;nbsp;B B

Rothpletz 3 on the strength of fresh observations and is replaced by ^ ^ g-

I have never had opportunity to examine specimens in the high state of preservation necessary for these observations. While then Stur contrastsnbsp;the Course of the strands in Archaeocalamites with that in Equisetum, asnbsp;he has construed it, he endeavours in a detailed discussion of the subject *nbsp;to show the possibility of a gradual transition of the one into the other

A and in Archaeocalamites radiatus w , but the latter is contested WWnbsp;nbsp;nbsp;nbsp;Anbsp;nbsp;nbsp;nbsp;W W

' 'Williamson (1), ix. � Stur (5), (8), (9). nbsp;nbsp;nbsp;^ Rothpletz (1), pp. 5. 6-nbsp;nbsp;nbsp;nbsp;� Stur (5), p. 558.

during the formation of the Ostrau deposits, and thus arrives at last at a phylogenetic arrangement of all the Calamariae. Calamites ramifer, Stur,nbsp;C. cistiformis, Stur, C. approximatiformis, Stur, and C. ostraviensis, Stur,nbsp;all figure in this list as transition forms. It need scarcely be observed onnbsp;what feet of clay the whole structure stands. But Stur goes much furthernbsp;still in his conclusions. He places Sphenophyllum also with Calamariae on

this he relies chiefly on his examination of Sphenophyllum tenerrimum, Ett. from the Culm ; but it may still be doubted whether this speciesnbsp;belongs to the genus, and the question will have to be considered later on.nbsp;He makes Sphenophyllum as well as Annularia and Asterophyllites to benbsp;nothing more than heteromorphous branches of Calamitae, bearing two different kinds of fructifications, one of which therefore will contain macrospores,nbsp;the other microspores. He claims indeed to have found Sphenophyllae growing out of Asterophyllitae but he has not figured his specimens. It maynbsp;well be asked, whether they were not merely branches of broad-leaved andnbsp;narrow-leaved Sphenophyllum in connection with one another. The readernbsp;should refer to the remarks on this point in the chapter of this work onnbsp;Sphenophylleae, and to Weiss� critical examination of Stur�s views Lastly,nbsp;Stur �, setting out from the results (.?) thus obtained from fossil forms,nbsp;even attempts to arrive in the reverse way at conclusions respecting thenbsp;morphology of living Equisetae, which contain much that is surprising tonbsp;the botanist. Weiss� ^ summary account of these speculations should benbsp;consulted.

On the nodal line between the two rows of prominences, which have now been described, the cast also shows the scars of the attachment of thenbsp;branches in varying number and arrangement. These are disk-shapednbsp;surfaces, which are often somewhat depressed and patelliform, and at theirnbsp;periphery they usually show radial striation due partly at least to thenbsp;mutual convergence in that quarter of the contiguous and laterally adjacentnbsp;ridges and furrows. In a figure given by Weiss � a small portion of thenbsp;stony substance has remained behind in the patelliform scar, and concealsnbsp;the peripheral striation ; and this is not an uncommon occurrence. In thosenbsp;Calamitae which have only a few branch-traces in the nodes, we may oftennbsp;observe on the nodal line outside and between these traces numerousnbsp;dot-like marks, to which a few adjacent ribs converge from above andnbsp;from below. It is natural to suppose that these marks are the tracesnbsp;of undeveloped lateral branches. These traces are seen in a particularly

� Slur (10). nbsp;nbsp;nbsp;* Weiss (8).nbsp;nbsp;nbsp;nbsp;� Stur (8).nbsp;nbsp;nbsp;nbsp;� Weiss (5), p. 13, note. * Weiss (5),

t. 2, f. 3; t. 7, f. 2 ; t. 13, ff. 1-3; t. 21, f. 5; t. 25, f, i, and Stur (5), t. 20, f. 4. nbsp;nbsp;nbsp;� Weiss (5),

beautiful and well-pronounced form as rosettes of striated protuberances on the mould-plates of certain large stems of Calamitae with short members,nbsp;for example in Calamites multiramis ^; these plates undoubtedly representnbsp;the outer surface of the ring of wood, which is partly preserved in the formnbsp;of a thin coating of coal. The varied and peculiar arrangement of the scarsnbsp;of the branches on the nodes, for example in the group known as Calami-tinae, will be noticed again below. Certain anomalies in the sculpture, suchnbsp;as occur here and there on the internodes, but from which no conclusionsnbsp;can be drawn, will be found figured and described in Weiss

Now that the casts of Calamitae which are produced by the filling up of the medullary cavity have been thus fully considered, it remains only tonbsp;add a few words concerning the specimens which represent the outer surfacenbsp;of the stem. This surface, which in ordinary Calamitae is only preservednbsp;in a rind of coal, is either quite smooth or is folded in slight wrinkles ; thenbsp;nodes are indistinct, and are perhaps marked only by the presence of anynbsp;flat patelliform branch-traces that are present. No leaves are seen ; eithernbsp;there were none, or they dropped off early, or were simply not preserved.nbsp;Probably the latter supposition comes nearest to the truth, for since specimensnbsp;of some aberrant forms of Calamitae, the Calamitinae and Archaeocalamitesnbsp;radiatus, have actually, though rarely, been found bearing leaves, we mustnbsp;ultimately assume that the rest of the group were furnished with leaves. Wenbsp;shall have something more to say about these remains of leafy stems furthernbsp;on, when describing the groups to which they belong.

A classification of the Calamitae is a difficult task. It is exactly in the casts that the characteristic marks are so sparingly preserved to us; and ifnbsp;We must be content consciously to have recourse to an artificial arrange-nient, as best fitted to give a clear view of the whole, the one framed bynbsp;Weiss� is recommended by its simplicity and convenience, and by thenbsp;circumstance that it nowhere oversteps the frame supplied by the remainsnbsp;cf stems. Weiss has himself described with clearness the objects which henbsp;had in view in his divisions, and the importance which he attaches to them.nbsp;He says* distinctly: �A grouping of Calamitae without regard to theirnbsp;appendicular organs, especially the organs of fructification, is only a morenbsp;or less elegant mode of getting them arranged in some order, a mechanicalnbsp;procedure for practical convenience,' and in another place : � If we neverthe-Hss propose to group the Calamitae according to sterile bits of stems, andnbsp;*iot even to employ their elementary structure as a principle of division, thenbsp;only value of such a classification would be to make it more easy to get anbsp;general view of the whole from certain interesting points.� Such points arenbsp;Especially the distribution and position of the branches ; and if Stur refuses

to allow that these have any systematic value, Weiss ^ shows that this is virtually because he has united a number of badly identified specimens intonbsp;one species. At all events Stur has not found a better character for thenbsp;distinction of species to take their place.

Weiss then distinguishes four form-groups, genera if we like to call them so, of a provisional character. The first of these, named Stylo-calamites, Weiss, and embracing the typical forms Calamites Suckowii andnbsp;C. arborescens, Stbg, is characterised by the unusually small number ofnbsp;branches on the stems, which for long distances may sometimes be entirelynbsp;without a branch. The pillar-like stems are composed of shorter and longernbsp;members without regularity in their succession ; the ribs alternate regularlynbsp;at the nodes. The chief example of the second group, Eucalamites, Weiss,nbsp;is Calamites cruciatus and Weiss also places in it C. ramosus, Artis. Thenbsp;former species, as has been already said, is placed by Grand� Eury withnbsp;Calamodendron, The pillar-like stems show alternating ribs at the nodesnbsp;and are copiously branched, one branch springing from each node or severalnbsp;together, which then alternate in the successive whorls. The forms with anbsp;few, one to two, bi'anches to each node are classed by Weiss with Calamitesnbsp;ramosus, those with three, four, six or more with C. multiramis, Weiss,nbsp;which shows the highest number of branch-traces, about nine. A figure ofnbsp;it is given in Weiss

Somewhat more of detail is required in noticing the third group Cala-mitina, Weiss (Asterophyllites, Ren., Calamophyllites, Grand� Eury), since it includes all the specimens in which the surface of the stem is seen withnbsp;the leaves attached. The casts of Calamitinae are chiefly found in collections under the name Calamites varians, Stbg, some of them under thatnbsp;of C. approximatus, Brongn. Their distinguishing mark is that branch-traces are not found on every node; the nodes which have them arenbsp;separated from each other by a number of nodes on which no branchesnbsp;were formed. The nodes with branches display a great number of scarsnbsp;which are usually in lateral contact with one another. Where the ribs arenbsp;distinctly shown they alternate in the usual manner. The number of thenbsp;nodes which intervene between the periodically recurrent whorls of branchesnbsp;is generally constant in each specimen ; there are, as far as is known, twonbsp;at least and nine at most; the intermediate numbers three, four, six andnbsp;eight are frequently observed. The details connected with this point willnbsp;be found in Weiss Between the periodic nodes a definite relation isnbsp;usually apparent in the length of the internodes, which either increases ornbsp;diminishes from below upwards.

In this third group, as in all other Calamitae, there is no appearance of the characteristic ribs on the surface of the stein. The surface is either

state of preservation here described were formerly known by Lindley and Hutton � and others as Cyclocladia; but the name was afterwards appliednbsp;to quite different objects (Halonia). A well-figured Calamitina of thisnbsp;bind, which was placed with Ulodendron, appears in Steinhauer^ undernbsp;the name of Phytolithus parmatus.

On the other hand there are specimens with perfectly smooth surface, and with the leaves still attached, so that the scars of course are concealed.nbsp;To these belong the famous Wettin fossils, which have been figured againnbsp;^ud again, first by Germar�, then by Schenk�, and lastly by Weiss

perfectly smooth, or is traversed by single longitudinal folds and by many irregular transversal wrinkles, which can^ evidently be only produced bynbsp;displacement, as Stur rightly insists and do not represent an original feature.nbsp;Specimens from this group, such as are kept in the collections, show notnbsp;unimportant variations, which are due in part at least to specific differences,nbsp;in part perhaps to dissimilar mode of preservation. Ordinarily we find onnbsp;every node a row of small leaf-scars laterally in contact with one another,nbsp;which are broader in the transverse direction and have a trace-point in thenbsp;centre. A similar row is also observed on the nodes of the branches, butnbsp;they are pushed in various ways out of their regular annular position bynbsp;the large disk-like scarsnbsp;of branches which arenbsp;developed close to themnbsp;(whether above them ornbsp;beneath them cannot benbsp;determined), as is excellently described bynbsp;Weiss ^ (Fig. 42). Goodnbsp;figures of specimens ofnbsp;this kind are to be foundnbsp;in Weiss Ettingshau-sen ^ and O. Feistman-tel In one of the last-rnentioned specimensnbsp;�which have been described by Weiss, thenbsp;leaves are still attachednbsp;on both sides in the formnbsp;of thin curved lines ofnbsp;ooal. Specimens of the

, Stur (5)j p, 162, nbsp;nbsp;nbsp;2 Weiss (5), t. i6a, ff. 7, 8, and t. 17, f. I.nbsp;nbsp;nbsp;nbsp;...

�^on Ettingshausen (5), t. i, f. 4. O. Feistmantel (3), t. i, f. 8. nbsp;nbsp;nbsp;� Lindley and Hutton (1),

t. 130. nbsp;nbsp;nbsp;7 Steinhauer (1), t. 6, f. 1.nbsp;nbsp;nbsp;nbsp;� Germar (1), t. 20, f. i. � Schenk (2), t. 34,

(Fig. 43), and to these must be added the specimen described by Weiss ^ from Langendreer and perhaps Hippurites longifolia^. Nothing can benbsp;seen of the nodes; all that appears is a regular transversal row of leaves,nbsp;which do not touch one another at the base but are separated by tolerablynbsp;wide gaps, and are very peculiar objects (Fig. 43 B). They are composed ofnbsp;an elliptical thickened basal portion,which is traversed bya median furrow andnbsp;is plainly distinguishable from the long narrowly lanceolate sharply pointed

lamina. The lamina is often torn away and the basal portion alone remains. Leavesnbsp;which have fallen off entire are according tonbsp;Weiss� Poacites zeaeformis. I have examined the figure in Schlotheim ^ and findnbsp;it comparable rather with the lobes of tornnbsp;sheaths of Equisetum, but it is in too roughnbsp;a state to allow of a certain determination.

There are other specimens again besides these, in which we find the leaves attached to the surface of the stem. Butnbsp;the basal portion of the leaves is of anbsp;different form, being shorter and broader,nbsp;and therefore a less conspicuous object.nbsp;In these pieces the continuous line of scarsnbsp;which is of so common occurrence mightnbsp;remain behind after the fall of thenbsp;leaves. From the list of figures we maynbsp;cite those of O. Feistmantel � and Weiss�nbsp;(Calamitina varians, var. semicircularis fromnbsp;Bras in Bohemia) and perhap.s Hippuritesnbsp;gigantea in Lindley and Hutton : butnbsp;it is not quite certain that the latter fossilnbsp;belongs to the present group, as nonbsp;branch-node has been preserved. In all these forms the small branch-scars, which do not touch one another laterally, are peculiarly formed, beingnbsp;somewhat flattened longitudinally on one side, whence the name of thenbsp;variety � semicircularis.�

Stur� explains the fact, that in Calamitinae it is the surface of the stem which is so frequently observed, by saying that the solid firm outernbsp;membrane was set free by maceration, and was then buried by itself. Henbsp;states that shreds of the outer membrane belonging to Calamites varians.

� Weiss (5), t. 17, f. 2. nbsp;nbsp;nbsp;� Lindley and Hutton (1), vol. i, t. 190.nbsp;nbsp;nbsp;nbsp;^ Weiss (5).

* von Schlotheim (1), p. 416, t. 26. nbsp;nbsp;nbsp;� O. Feistmantel (3), t. 2, f. i. � Weiss (5), t. 16, f. 6.

� Lindley and Hutton (1), vol, ii, t. 114. nbsp;nbsp;nbsp;* .Stur (5), p. 162.

Stbg, large enough to cover several internodes and sometimes with the leaves still attached, are constantly found at Radnitz along with thatnbsp;species. This explanation, which Weiss ^ apparently does not accept,nbsp;since he dismisses it in a few words, seems to me not improbable. Thenbsp;pieces of leafy stem from Wettin are actually shreds of this kind, andnbsp;answer exactly to Stur�s description. This appears from the figures, butnbsp;I have been able to satisfy myself on the point from the specimens themselves, which were kindly sent to me by von Fritsch. The specimennbsp;figured by Weiss ^ shows the flatly convex outer side, as may be seen fromnbsp;the leaves lying on it and separated from the epidermis by a thin layer ofnbsp;the stone. It is quite irregular in its outline, and nothing can be seen of thenbsp;cast, of which it must have formed the surface, indeed the gray slatynbsp;rock contains a couple of nodular concretions immediately underneath it.nbsp;Another of the specimens which I received from von Fritsch shows anbsp;confused mass of these shreds of leafy outer membrane. The figure innbsp;Ettingshausen � may also be compared. The often cited and often figurednbsp;piece from Wettin * shows partly the epidermis, partly a ribbed impressionnbsp;of the inner surface ; Stur explains this by supposing that after the corticalnbsp;tissue was destroyed by maceration, the mineral matter must have madenbsp;its way in between the loosened epidermis and the wood, which was stillnbsp;intact. The impression, so far as it shows longitudinal ribs, must thereforenbsp;answer to the outer surface of the secondary wood, the remainder of it tonbsp;the inner side of the epidermis; then by uneven fracture partly the onenbsp;and partly the other side of the cylindrical fracture was disclosed to view.nbsp;So long as I had only the figures before me, I could not clearly judge ofnbsp;the grounds for this opinion ; for the figures are not alike. In Germar �nbsp;and Schenk � the ribbed portion lies below the epidermal surface, in Weiss�nbsp;figure above it. I suspect therefore that the two first specimens show onenbsp;face of the fracture, the third the other face; the contours also are identical in the pieces of the two first authors, in Weiss they are essentiallynbsp;different. I have received Weis.s� original specimen from Halle, and havenbsp;therefore been able to satisfy myself of the correctness of the figure. It isnbsp;a. fragment of a mould, in which the portion of the wood which shows thenbsp;longitudinal ribbing lies naturally a little above the outer surface, fromnbsp;quot;Which it is separated by a thin layer of stone ; small remains of the extremely thin rind of coal still cling to its depressions. This last circumstancenbsp;shows that, as the coal could only be really formed from the wood, thenbsp;latter lay inside the ribbed surface, and that the ribbing therefore corresponds to the surface of the wood, and not to the medullary tube. Andnbsp;this is exactly the state of things required by Stur�s view, which therefore

manner by means of repeated bifurcations. Of this fact there can be no doubt in presence of Stur�s ^ many and excellent figures. The leaves innbsp;older whorls stand out at a right angle from the axis ; at the upper extremities of the branches, which are preserved in great numbers, theynbsp;close over one another like leaves in a bud. This says little for the viewnbsp;adopted by Heer on the strength of some evidently less perfectly preserved specimens, that the organs beforenbsp;us are of the nature of roots. Moreover,

Stur � has figured several pieces of stem curved at the base, and bearing on theirnbsp;convex side small tufts of manifest roots,nbsp;which have small resemblance to thenbsp;leaves which we have been describing.

It is true that we find somewhat different accounts of the foliage of Archaeocala-mites in Brongniart^ and Schimper�.

These accounts are based on a famous specimen from the Culm of Burbach nearnbsp;Thann in the Vosges and now in thenbsp;Museum at Strassburg, which consists ofnbsp;a cast and a piece of the mould whichnbsp;belongs to it. On the surface of thenbsp;transverse fracture of the piece of stonenbsp;Containing the mould is seen the half ofnbsp;a leaf-whorl projecting at a right angle.

This bit of whorl was taken by Brong-niart for a close sheath having blunt teeth. But Stur, with whom Schimpernbsp;in his later publications agrees, hasnbsp;shown that each leaf in the whorl isnbsp;really free to the base, and that itsnbsp;extremities which are of unequal lengthnbsp;are not the real apices. He has figured � a similar whorl from thenbsp;Moravian slates, which is spread out on the surface of the slate, likenbsp;the specimen from the Vosges, and also shows only the basal portionsnbsp;of the leaves, all the rest having been lost by maceration and rendingnbsp;before the plant was buried. The comparison of these leaves with thosenbsp;of Calamitinae tells us of the great differences which there must have beennbsp;'ri the series of Calamariae. Sphenophyllum tenerrimum, Ett., which we

in this case also seems to me to be highly probable. When Stur ^ indeed goes on to say that all the Calamitinae may have been the fertile shootsnbsp;of other ordinary Calamitae, and supposes the character of this group tonbsp;have been analogous with that of the homosporous Equisetae, he willnbsp;find none to share that opinion until he succeeds in producing good andnbsp;sufficient reasons for it.

The last group is formed of the genus Archaeocalamites, Stur, of which A. radiatus (Bornia radiata, Brongn., Calamites transitionis, Gopp.)nbsp;is the typical species. The essential character of the genus, as given by allnbsp;authors, is the constant non-alternation of the broad flat ribs on the cast,nbsp;in which also the indentations made by the nodes are often not verynbsp;pronounced and distinct. The rows of small knobs on the nodal line arenbsp;seldom plainly seen, and authors differ in opinion respecting their relativenbsp;position, as has been already stated. Casts of this kind, usually roundnbsp;but sometimes pressed flat and without any compact rind of coal, arenbsp;exceedingly plentiful in the Upper Devonian and Carboniferous systems,nbsp;and are characteristic of them ; figures of them will be found in manynbsp;works, in Schimper ^ for example and in Stur They are usually withoutnbsp;branches, but, as more recent authors, Stur and Weiss especially, havenbsp;pointed out, they are occasionally beset with numerous branch-traces,nbsp;which are found singly or several together on all successive nodes butnbsp;without giving signs of any regular order. Weiss supposes that the twonbsp;pieces may have belonged to different parts of the shoot-system ; in anynbsp;case the branched specimens must be very rare, for I have never yet seennbsp;one of them.

Our Archaeocalamites occurs in a peculiar state of preservation in the roofing-slates of Moravia. Its remains lie squeezed perfectly flat betweennbsp;the slates ; the organic substance according to Stur ^ � is replaced only bynbsp;a very thin, often transparent, brownish membrane, which may have a goldnbsp;and silver lustre.� Larger stems are very rarely found, and are always in anbsp;fragmentary state. But these slates also contain a number of branchesnbsp;which have their appendages attached to them, and show the charactersnbsp;of Archaeocalamites in so striking a manner that Ettingshausen � has nonbsp;doubt that they belong to it. This view has since been confirmed bynbsp;Stur�s� thorough investigation of these remains, and the two authors alsonbsp;refer Sphenophyllum furcatum � to the same genus. The appendages ornbsp;leaves, as we prefer to call them with Stur and Ettingshausen, are attachednbsp;to the nodes in many-membered whorls ; they are free and non-coherentnbsp;down to the base, are narrowly linear, and are branched in a remarkable

might also be inclined to place with Archaeocalamites rather than with Sphenophyllum, will be noticed below.

The distribution of Calamitae in the series of deposits is comparatively limited, since they cannot be certainly shown to have existed before thenbsp;Upper Devonian formation and they disappear again before the Trias.nbsp;Archaeocalamites is the only genus found in the Devonian beds, and in thenbsp;Culm it is the predominating form. Then its place is taken by Euca-lamitae and Stylocalamitae, which are still represented in the Rothliegendenbsp;by one very abundant form, Calamites gigas. The Calamitinae alsonbsp;are found throughout the true Coal-measures, but do not reach the Rothliegende.

Further, impressions of articulated branches or branch-systems with leaves in whorls are found distributed throughout the Carboniferousnbsp;formation in equal abundance with the casts of stones; and these onnbsp;account of their habit and the striation, like that of Calamitae, which isnbsp;often to be plainly seen on their older and stronger internodes, it has longnbsp;been the custom to refer to Calamariae. Though in this case we have nonbsp;casts, but only impressions on which the substance of the branch is usuallynbsp;preserved as a rind of coal, we may yet unhesitatingly refer the striation,nbsp;where it is present, to the ribs of the woody body which have left theirnbsp;impression behind them through the thin rind in the stone. It, is in accordance with this, that the terminal ramifications usually show no striae;nbsp;it may be presumed that no secondary wood was formed in them.

It has been the custom to distinguish these forms into two groups according to the nature of the leaf-whorls, Annulariae found only in thenbsp;Carboniferous formation, for Dawson�s ^ Devonian forms can scarcely benbsp;taken into consideration, and Asterophyllitae which appear to occur innbsp;Devonian deposits In Annularia, Brongn., all the leaves of the whorlnbsp;cohere at their base into a small patelliform lamina, which like a flat collarnbsp;surrounds the stem as it passes through its centre. The leaf-teeth arenbsp;traversed each by a single nerve, and their form varies with the species;nbsp;in the well-known and abundant Annularia longifolia, which Rothpletz ^nbsp;divides into several species, they are elongate-lanceolate and pointed ; innbsp;the equally common A. sphenophylloides, Ung., they are much broader,nbsp;wedge-shaped, and then suddenly contracted, with a blunt rounded extremity. In Asterophyllites, Brongn. (Calamocladus, Schimp.), on thenbsp;other hand the leaves are quite separated from one another, and they arenbsp;seldom placed at a right angle to the axis, as in the other genus, butnbsp;usually incline forwards. They are simple, usually narrow, acicular ornbsp;linear, of very various but sometimes of considerable length. Good figures

of different forms of this group are found in Grand� Eury^, O. Feistmantel^ Schimper Zeiller Weiss �, and Ettingshausen These Asterophyllitaenbsp;differ much in the mode and copiousness of their branching and generally innbsp;their whole habit. Stur^ has recently asserted that some of the formsnbsp;hitherto unhesitatingly referred to this group had their leaves once dicho-tomously divided, and he distinguishes them as Volkmannia, Stbg; butnbsp;this name has in the course of time been applied to so many differentnbsp;things that it would be better to abandon it altogether.

Similar statements are made by Schenk� on the strength of a leaf-whorl from St. Ingbert in the collection at Munich. The branches, also with dichotomously divided leaves, which are placed by Grand� Eury²nbsp;with Arthropitys and are named Bryon, have an entirely different habitnbsp;and require further study. Stur distinctly claims Volkmannia gracilis andnbsp;also Asterophyllites capillaceus for his genus Volkmannia. Numerousnbsp;specimens collected by myself from the Skalley mine at Dudweiler nearnbsp;Saarbriicken, which agreed perfectly with the figure of the first of the twonbsp;species, did not satisfy me as regards this particular character.

We have then gradually become accustomed to look upon Asterophyllitae as branches and branch-systems of Calamitae. Schimper^^ indeed frankly named the genus Calamocladus. The Annulariae on the contrarynbsp;have always passed for independent herbaceous water-plants. It would benbsp;in vain, however, to seek for distinct proofs of either view in the older literature, if we are not prepared to allow the branch-members of some Asterophyllitae which resemble Calamitae to pass for Calamitae; nor can wenbsp;derive any help from the anatomy, for no leaf-bearing branch of the groupnbsp;showing structure has yet been found. Grand� Eury^� indeed has discovered an indubitable Calamitina with Asterophyllitae attached. Renault^^,nbsp;to whom we are indebted for a figure of the piece as it really looks, hasnbsp;therefore transferred the name Asterophyllites to stems of Calamitinae also,nbsp;and Williamson does the same. But since this specimen does not justify usnbsp;in assuming that all Asterophyllitae were borne by Calamitinae, I can onlynbsp;see in this nomenclature a change for the worse. If all stems of Calamitaenbsp;bad the foliage which was described above and which is quite different fromnbsp;that of Asterophyllites, Grand� Eury�s observation would prove that therenbsp;Was an interesting heterophylly in the different axes of these plants. Weissnbsp;has shown that Calamitae were not all alike in this respect. He found

Grand� Eury (1), t. 32, ff. 2, 3. nbsp;nbsp;nbsp;� O. Feistmantel (3), t. 10.nbsp;nbsp;nbsp;nbsp;� Schimper (1), tt. 22, 26.

* nbsp;nbsp;nbsp;Zeiller (3), t. 159.nbsp;nbsp;nbsp;nbsp;� Weiss (1), t. 12.nbsp;nbsp;nbsp;nbsp;� von Ettingshausen (3).nbsp;nbsp;nbsp;nbsp;� Stur (5), p. 133.

* nbsp;nbsp;nbsp;Schenk (2), p. 235 ; t. 37, f. 2.nbsp;nbsp;nbsp;nbsp;� Saporta et Marion (2), p. 46.nbsp;nbsp;nbsp;nbsp;� Sternberg, Graf von, Heft

5-8, t. 15, f. I. 11 Weiss (6), p. 61; t. tt, f. I. nbsp;nbsp;nbsp;Schimper (1).nbsp;nbsp;nbsp;nbsp;Grand� Eury (1), t. 4

(figure diagrammatically represented). ² Renault (2), vol, ii, t. 17, fi nbsp;nbsp;nbsp;Williamson (1), v.

Annulariae, answering nearly to Annularia radiata, Brongn., attached as leafy branches to Calamites ramosus, Artis. He says on this point: � Calamites,nbsp;which is particularly easy to recognise in the older portions of its stem bynbsp;the form of its members, by its ribbing, by the large scars of the mainnbsp;branches, and indeed by its general habit, permits of our bringing a largenbsp;number of fragments together with certainty under one species. The considerable number of individuals, which have been found recently in thenbsp;Ruben mine near Neurode in Lower Silesia, almost all in the clay-slatenbsp;roof of seam No. 7, and have been most diligently collected, often in greatnbsp;slabs, by Chief-Inspector V�lkel, has enabled us to form a more perfect ideanbsp;of the whole plant in this case than in any other that could be named. Thenbsp;numerous figures which we have given of it rest upon a much larger numbernbsp;of original specimens, so that where there may still be some gaps observablenbsp;in our figures, we might venture in fact to fill them in, and we believe therenbsp;can be no longer any doubt as to whether all the single pieces here broughtnbsp;together really belong to one another.� Hence both Asterophyllitae andnbsp;Annulariae may belong as leafy branches to Calamitae, though it does notnbsp;follow, as Weiss has well shown, that they must in all cases have belongednbsp;to them. It may prove that there were arborescent and herbaceous formsnbsp;with similar leaves in the group of Calamariae. In any case the classification of Renault h who constitutes two separate families, Asterophylliteaenbsp;and Annularieae, in his heterosporous Equisetinae, is thus shown to benbsp;quite arbitrary.

We have long been acquainted with a large and constantly increasing number of spike-like remains of fructifications with lateral sporangiferousnbsp;members arranged in whorls. As some of these fructifications have beennbsp;found connected in a way which admits of no doubt with specimens ofnbsp;Calamariae, we may assume that the rest of them also belong to thatnbsp;group. Heterospory has very recently been ascertained in two instances,nbsp;the macrosporangia occupying the basal, the microsporangia the apicalnbsp;portion of the spike. Williamson^ showed this in the case of a spikenbsp;supposed to belong to Calamostachys Binneyana, and Renault � in that ofnbsp;another which he describes as belonging to Annularia longifolia. Whethernbsp;this fact is to be assumed as true of all spikes of Calamariae, as is done bynbsp;Renault, had better be left undecided, and such is Weiss� opinion. Thenbsp;cases of Lycopodium and Selaginella warn us to be cautious in drawingnbsp;such conclusions.

The spikes, like the other parts of the plants, are presented to us, as might be expected, in different states of preservation. They are eithernbsp;petrified, and then we are able to study the details of their structure; ornbsp;they appear in impressions, in which case, if the lateral members have been

brought close to one another, the surface only can be seen, if the arrangement is looser, the organisation also can be examined, but usually much less perfectly than in the petrified specimens. Owing to this difference in thenbsp;mode of preservation and also to the general similarity of habit, the identification of the several specimens with one another is difficult and uncertain.nbsp;Premature and misplaced attempts of this kind are among the chief causes ofnbsp;the distracting nomenclature and synonymy, which is nowhere a more seriousnbsp;hindrance to the study of the forms than it is in this case. The old namesnbsp;especially, Volkmannia, Stbg, Bruckmannia, Stbg, have been differently interpreted by almost every later author, and have been connected with variousnbsp;recently discovered types. It will conduce to a better understanding, if withnbsp;Weiss ^ we discard them altogether. It is certain that a final system of classification and nomenclature is at once excluded by the fragmentary characternbsp;of our knowledge of all these remains, and that our only object must be tonbsp;frame provisional groups, which, corresponding to the state of our knowledge,nbsp;may afford a general view of the facts as they have been ascertained, Weiss�nbsp;arrangement secures this advantage in a high degree by refusing to makenbsp;every difference though not unimportant in itself the occasion of a newnbsp;name, and by attending only to the ground-plan of the structure; we willnbsp;follow it therefore in our subsequent remarks.

With the exception of a few remains of abnormal character which will be considered at the end of the chapter, the spikes of Calamariae are allnbsp;cylindrical in form and more or less thickly covered with leaves, while therenbsp;is much difference in the relative size of the parts. Wherever it has beennbsp;possible to examine them, they have been found to be composed of fertilenbsp;and sterile whorls of leaves which succeed one another in regular alternation.nbsp;The sterile whorls usually consist of a considerable number of lanceolatenbsp;sharply-pointed leaves, which are either free or united together by a largernbsp;or smaller portion of their bases, the free apices being bent upwards in suchnbsp;a manner as to lie like tiles on the leaf-bases of the whorl next above them ofnbsp;the same description, and to arch over the interposed fertile leaves, being thusnbsp;the only ones seen in the surface-view of the whole fructification. Thenbsp;fertile leaves are usually, as in Equisetae, not united together, and arenbsp;furnished with an umbellately peltate lamina, which bears the sporangia onnbsp;the under side. According to the relative position of the two whorls to onenbsp;another Weiss distinguishes the types Calamostachys and Palaeostachya, tonbsp;which latter Huttonia is attached. The entirely provisional names Paracala-nrostachys and Macrostachya are applied to spikes of imperfectly ascertainednbsp;structure, in order to connect them with one or the other type, Macrostachyanbsp;including the forms which in habit resemble forms of Palaeostachya. To

these must be added Cingularia, Weiss, a fructification of anomalous structure. Stur^ considers that he finds his three distinct whorl-traces in regular and characteristic position in each case in the fructification as well as in thenbsp;stems and branches; but his speculations on this point have been alreadynbsp;noticed, and it is unnecessary to go further into them in this place. It isnbsp;plain that the impressions, the only specimens here in question, are not tonbsp;be directly compared with the interior casts, on the study of which thisnbsp;author has founded his views.

In Calamostachys, Weiss (Fig. 45 A), the umbellate sporangial leaves are inserted exactly in the middle between every two leaf-whorls; theirnbsp;stalks are at right angles to the axis of the spike, and bear the sporangianbsp;at their more or less distinctly expanded and scutiform extremity. Ournbsp;knowledge of the structure of the fructification in this genus is chieflynbsp;derived from a specimen preserved in siderite from Hattingen on the

Ruhr, which was first described and figured by Ludwig^, then named Volkmannia Lud-wigii, Carr, by Carruthers� and Calamostachys typica, Schpr. by Schimper*, and hasnbsp;finally been fully elucidated by Weiss�nbsp;with the addition of fine figures. Thenbsp;specimen contains a number of spikes lyingnbsp;parallel to one another, and may thereforenbsp;be a fragment of a tuft of fructifications.nbsp;The leaves in the sterile whorl, about twelvenbsp;in number, are free almost to the point ofnbsp;attachment, and from their horizontal basalnbsp;portion the lanceolate upper part curvesnbsp;upwards at a right angle, and exactly covers the curved portion of thenbsp;leaves of the whorl next above. The whorl of sporangiophores insertednbsp;between two leaf-whorls has six members; the members in the successive sporangial whorls are superposed; of the twelve members innbsp;the leaf-whorls six appear to alternate, six to be superposed. Thenbsp;substance of the sporangiophores, especially in the small scutiform expansion, is partly preserved in a few cases only. But the sporangianbsp;themselves, which are suspended in fours in a diagonal position from thenbsp;scutellum of the sporangiophore, are comparatively well preserved. Theirnbsp;wall, which is of one cell-layer only, at least in its present state, is formednbsp;of reticulated cells. The doubts expressed by Weiss * respecting the connection between the thickening-ridges and the membrane may have nonbsp;foundation. The sporangia are filled in uniform manner with the globular

spores, which show the triradiate ridge. From their size I should suppose them to be microspores, but this is not certain, for a similar spike, which willnbsp;be described presently, containing both kinds of spores, shows us that thenbsp;differences in size need not be very great, and that macrospores also may benbsp;formed in large numbers in a sporangium.

We have also learnt something respecting the anatomical structure of the axis Rind and pith partially preserved are parenchymatous, and arenbsp;separated from one another by a rather broad closed ring of wood nearlynbsp;triangular in shape. I was unable to form a clear idea of the character ofnbsp;the imperfectly preserved medullary sheath from the original sections sentnbsp;me by Weiss for my inspection. A preparation of Williamson ^ from thenbsp;nearly allied Calamostachys Binneyana will perhaps supply what is wantingnbsp;on renewed examination. What there was to be seen was quite in accordance with the structure of Calamitae, but I would rather not at presentnbsp;venture on positive and detailed statements.

A second species, the organisation of which is well known, Calamostachys Binneyana, Schpr., was first figured by Carruthers� as Volkmannia Binneyi, then by Binney ^ as the fructification of his Calamodendron commune, and lastly and repeatedly by Williamson �. It is smaller than thenbsp;preceding, and while the structure is in essential points the same it isnbsp;distinguished by the much smaller development of its woody body, andnbsp;especially by the circumstance that the leaves of the sterile whorls are seennbsp;to be united to one another almost as high as the point where they bendnbsp;over, and therefore form on the tangential section transverse connectednbsp;laminae ensheathing the sporangiophores, as is represented in Binney Sonbsp;far all these spikes, which are apparently plentiful in the English calcareousnbsp;nodules, agree with one another. Nevertheless both to myself and Weissnbsp;it appears doubtful whether they really all belong to one another, whethernbsp;different species of similar habit have not been included under the onenbsp;name. Williamson for example, describes a fragment of a spike whichnbsp;has macrosporangia below and microsporangia above. The two are exactlynbsp;alike and contain numerous spores, which are distinguished merely by anbsp;moderate difference in size, the larger having about three times the diameternbsp;of the smaller. Now it is very remarkable that Binney, though he figuresnbsp;the radial section of the base of a spike ¹, found no such macrosporangia innbsp;it, and it may be suspected that there were none in this particular spike.nbsp;And on the other hand in the collection of sections in the Botanical Department of the British Museum I have seen similar sections of spikes whichnbsp;appeared to contain only macrospores, and these seemed to show the three

Weiss (5), t. 34. nbsp;nbsp;nbsp;Williamson (1), x, t. 16, f. 16.nbsp;nbsp;nbsp;nbsp;¹ Carruthers (15).nbsp;nbsp;nbsp;nbsp;¹ Binney (1),

I. tt. 4, 5. nbsp;nbsp;nbsp;5 Williamson (1), v, t. 6 ; X, t. 15, ff. 13-17 ; XI, t. 54, ff. 23-26.nbsp;nbsp;nbsp;nbsp;� Binney (1),

1.1. 5. nbsp;nbsp;nbsp;� Williamson (1), XI, t. 54.nbsp;nbsp;nbsp;nbsp;� Binney (1), I, t. 5, f. 4.

small undeveloped sister-cells of the tetrad still distinguishable at their apex. Moreover in one of the specimens figured by Williamson^ the spores werenbsp;united in tetrads and still surrounded by the mother-cell, but this might benbsp;explained by the young condition of the fructification when it was buried.nbsp;The view lately expressed by Renault on the subject of Calamostachysnbsp;Binneyana will be noticed presently, when we are considering the speciesnbsp;which he has examined.

Weiss ^ has given the name of Calamostachys superba to a spike known only in longitudinal fracture, which, though not very well preserved, presentsnbsp;essentially the same conditions as the forms already noticed. Whether thenbsp;leaves of the sterile whorls, which are marked by the excessive elongationnbsp;of their apical parts, cohere or not cannot be ascertained^ as the specimennbsp;shows only the true radial section. It comes from the Augustus mine innbsp;the Plauensche Grund near Dresden, and is imbedded in a whitish clay.nbsp;There is no exact account of the mode of preservation. There is anothernbsp;specimen with it in the Museum at Dresden which was found in the samenbsp;spot, and which Weiss ^ has named Calamostachys mira. Its radial longitudinal section shows most distinctly the position of the two kinds of whorlsnbsp;and the point of attachment of the sporangia. But it also shows a portionnbsp;of the surface ; we see the free apices of the sterile leaves, which have undoubtedly become united together below into a horizontal lamina after thenbsp;manner of Calamostachys Binneyana. From the place where the leaf isnbsp;bent, and which is not covered by leaves of the whorl next beneath it, anbsp;lamelliform emergence hangs down like a curtain, the foi'm and limits ofnbsp;which cannot be determined, but which appears even on the sides of thenbsp;fracture in the form of a fine line of through section running down in frontnbsp;of the sporangiophores. Weiss says of it'^, �bracts . . . with a reflexednbsp;appendage protecting the sporangia.� We find something like it also innbsp;Huttonia. Weiss also cites as perhaps analogous with this form a specimennbsp;described and figured by Renault� and named Macrostachya infundi-buliformis, but which is of so questionable a character that I should notnbsp;attribute much importance to it.

Mention must also be made here of an object from Autun of which a section was made by Renault�, and which was described by him as thenbsp;fructification of Annularia longifolia. It is evidently a true Calamostachys,nbsp;though the attachment of the sporangia to the sporangiophore is not clearlynbsp;shown, and the sterile whorls of entirely free lanceolate leaves, being spreadnbsp;out flat, and even bent a little backwards in the basal portion, do notnbsp;cover the fertile leaves from the outside. The distinguishing mark innbsp;this spike is that its axis, which has a similar structure to that of Equisetum,

� Williamson (1), X, t. 15, f. 27. nbsp;nbsp;nbsp;�� Weiss (6), t. 4, f. 2.nbsp;nbsp;nbsp;nbsp;^ Weiss (6),t. 3, f. 1, and t. 4, f. i.

Weiss (6), p. 43. nbsp;nbsp;nbsp;� Renault (2), vol. ii, t. 19, ff. 7, 8.nbsp;nbsp;nbsp;nbsp;� Renault (16 and 2), vol. ii, t. 21, f. 2.

shows a hollow medullary cylinder and a weakly developed ring of primary bundles, in each of which is a lacuna. Renault says distinctly that he hasnbsp;found tracheal elements only in the immediate neighbourhood of the lacuna.

Renault^ has also described two other spikes of Calamostachys as Bruckmannia Grand� Euryi and B. Decaisnei. As they were obtainednbsp;from sections of the siliceous fragments of Grand� Croix, the details onlynbsp;of their structure are known. The structure of their axes agrees perfectlynbsp;with that of the form already described from Autun. A remarkable featurenbsp;is the large number of members both in the fertile and in the sterile whorls,nbsp;eighteen in the fertile whorls in Bruckmannia Grand� Euryi and twelve innbsp;B. Decaisnei, while in the sterile whorls there are twice these numbers.nbsp;With this agreement between the numerical relations and those of Calamostachys Ludwigii, we may assume that there was here the same alternationnbsp;as in that species. The sporangial leaves have the usual umbrella-like form;nbsp;they bear four sporangia, as Renault ^ distinctly states � and as his figurenbsp;shows, exactly in the position which they have been described as occupyingnbsp;in Calamostachys Ludwigii; the upper surface of the umbrella-roof is stronglynbsp;developed, and reaches to the leaf-whorl next above it and unites with it.nbsp;A branch of the foliar bundle, which bifurcates twice, runs to each of thenbsp;sporangia, which are themselves badly preserved. The spores in Bruckmannia Grand� Euryi lie connected together in fours in their mother-cells,nbsp;which also unite together in fours In the sterile whorl the leaves, whichnbsp;cohere below, form the often-mentioned horizontal disk, while their free uppernbsp;extremities bend sharply over and are directed upwards. There is one circumstance peculiar to these two species and sharply distinguishing them from thenbsp;typical forms just described, namely, that each sporangiophore is connectednbsp;by means of a vertical radial plate of tissue with the basal disk of the leaf-whorl next above it, and thus the sporangia, at least those in the uppernbsp;row, come to lie in radial compartments, which are open below but arenbsp;covered towards the outside by the extension of the umbrella-roof. In thisnbsp;way I understand, and I believe correctly, Renault�s description, in whichnbsp;there is absolutely no room for assuming the presence close beneath thenbsp;sterile whorl of a third whorl from which the plates spring, and whichnbsp;Stur � makes the foundation of his interpretation of the structure.

Renault�, who formerly ranked all the spikes which we have been describing with his Asterophylliteae and Annularieae, has very recently putnbsp;forth the view, that a part of them belong as male flowers to Arthropitys,nbsp;and to Calamodendron as he understands that genus. He expressly mentions Calamostachys Binneyana and C. Grand� Euryi as belonging to thisnbsp;division, and calls their spores directly pollen-grains. He relies in this

^ Renault (5), tt. 3, 4. Renault (5), t. 4, ff. 8, 9. nbsp;nbsp;nbsp;� Renault (5), p. 16.nbsp;nbsp;nbsp;nbsp;^ Renault (5),

matter partly on the structure of the wood in the axis of the spikes, partly on the details observed in the spores, in which he is persuaded that he seesnbsp;an interior cell-formation resembling that in the pollen-grain of Cordaitae.nbsp;He appeals also to the combination of the grains into tetrads, comparingnbsp;them with the teti'ads in the pollen of Angiosperms, and lastly to the circumstance that tetrads of perfectly similar character are found in thenbsp;pollen-chamber of certain Trigonocarpae and of Gnetopsis trigona. Henbsp;considers that the leaves of the sterile whorls were coherent in Arthropitysnbsp;and free in Calamodendron. The following sentence is characteristic � :nbsp;� In Calamodendron, Arthropitys, Annularia and some species of Astero-phyllites the fructifications are disposed in almost the same manner, thatnbsp;is to say, in the form of spikes composed of sterile and fertile whorlsnbsp;alternately; in most cases it is not possible to determine from the impressions the precise nature of the reproductive bodies belonging to thesenbsp;groups of plants, which are however somewhat remote from one another.�nbsp;It is not easy to criticise so dogmatic a statement, especially when thenbsp;grounds for it are all put before us in so brief and prefatory a manner;nbsp;but I would make the following observation. We have no analogue anywhere of a male flower with alternating fertile and sterile whorls of leaves.nbsp;That single spore-tetrads are found in the pollen-chamber of wind-fertilisednbsp;Gymnosperms is not conclusive; every cell which is smaller than the orificenbsp;of the micropyle will find its way into it, if it reaches it in its flight. Sporesnbsp;connected together in fours are not known indeed, but are perfectly possible.nbsp;The interior cell-formation can also prove nothing, if we suppose it to be anbsp;rudimentary prothallium, as I do notwithstanding Strasburger�s recentnbsp;arguments ; it is peculiar, as we know, to microspores, and the degree ofnbsp;development is of no importance. Lastly, what will Renault do withnbsp;Williamson�s spikes which contain macrospores and microspores? Thesenbsp;must necessarily remain with Annulariae in spite of their resemblance tonbsp;Calamostachys Binneyana. The sole criterion therefore remaining is thenbsp;secondary wood of the axis of the spikes, and with this we arrive once morenbsp;at the petitio principii of Brongniart�s school so often mentioned already,nbsp;which makes the understanding of their writings everywhere so difficult.

Lastly we may unite with Calamostachys Grand� Euryi certain fructifications which Weiss ^ names C. tuberculata (Fig. 45 B), while he makes the genus Stachannularia previously � created for them into a subdivision.nbsp;Renault and Grand� Eury ^ especially are inclined to regard the two asnbsp;directly synonymous, and they may be right, though as the states of preservation are not comparable we cannot at present have positive proof innbsp;either direction. Unlike the spikes hitherto described which are all petri-

factions, Calamostachys tuberculata, Weiss, is known only in the form of impressions, which however show the organisation since the sterile whorlsnbsp;are but slightly closed. It is a well-known spike already figured by Sternberg ^ as Bruckmannia tuberculata, and has been found not unfrequently innbsp;the Carboniferous schists of various deposits, at Ilmenau, at Saarbriicken,nbsp;at Zwickau, and at Schlan in Bohemia. According to Weiss two forms ofnbsp;organisation occur in Calamostachys tuberculata simultaneously on dilferentnbsp;spikes of the same plant. First there are the ordinary sporangiophoresnbsp;placed in the middle of the member, but each with only two sporangia, onenbsp;above and the other below. Besides these there are sporangiophores of anbsp;different character in the form of stout prickles like those of the rose andnbsp;bent downwards, which have a single sporangium only in the angle, and arenbsp;inserted immediately beneath a sterile whorl. This whorl has many members (twenty to thirty according to Weiss), and consists of upward-curvednbsp;linear leaves. Schenk ^ has since brought forward some important objectionsnbsp;to this account. He shows that the two types of organisation assumed bynbsp;Weiss are sometimes found even on the same spike, and he concludes fromnbsp;this that they only represent different modes of preservation of organsnbsp;originally alike. He says�; �What I dispute is, that two forms of sporo-phylls running a different course of development occur normally in thenbsp;same species, for the history of development in extinct plants is subject tonbsp;no other laws than those which govern it in living forms.� This, apart fromnbsp;the possibility which exists of a different development of the leaves bearingnbsp;macrosporangia and microsporangia, is no doubt true. Then to explainnbsp;the origin of the prickle-like sporangiophores, Schenk supposes that thenbsp;upper sporangium had its margin forced by the pressure beyond the sporan-giophore, and so the two became combined in a common impression.nbsp;Another similar explanation, which appears to myself and Stur�� to be stillnbsp;more satisfactory, and which is quite in keeping with Renault�s statementsnbsp;concerning Calamostachys Grand� Euryi, is that the prickle-like sporangio-phore is formed of the stalk of the sporophyll and the radial tissue-plate,nbsp;which connects the latter with the whorl above and which is here tornnbsp;away to the base. It is true that this mode of explanation presupposesnbsp;that there were not two or one but four sporangia present as usual, andnbsp;that only two of these are seen in the impression. The upper one of thenbsp;two, if still present, must also be flattened together with the vertical wingnbsp;of the sporangiophore into a homogeneous plate of coal. In this way thenbsp;structure of Calamostachys tuberculata may be reconciled with that of C.nbsp;Grand� Euryi. There remains only the peculiarity of the varying length ofnbsp;the internodes, for the whorls of sporophylls are undoubtedly placed far above

the middle of the interval between two leaf-whorls. Further researches will perhaps succeed in removing these doubts. Nearly allied to Calamostachysnbsp;tuberculata is C. calathifera \ but in this species only the normal sporophyllsnbsp;with two or four sporangia have at present been observed.

Palaeostachya, Weiss, differs from Calamostachys in having the whorls of the sporophylls inserted immediately above the sterile whorls, it may benbsp;almost said in the axils of their leaves, so that they project from them at anbsp;more or less acute and not at a right angle. Only one form of this type is

known in the petrified state, the rest are all impressions. The silicified specimen in question comes from Autun, and is named bynbsp;Renault Volkmannia gracilis^. He wouldnbsp;have done much better if he had given it anbsp;new name, considering the difference in agenbsp;of the beds of Autun and Radnitz, in thenbsp;latter of which Sternberg�s original Volkmannia was found; and also because Sternbergnbsp;unites branches and cones which it is possiblenbsp;do not belong to one another, while the roughness of his figures precludes the possibilitynbsp;of any certain identification. Renault�s � drawings show a hollow axis, and the well-knownnbsp;lacunae answering to the initial bundlesnbsp;reappear in its peripheral tissue.

The sterile whorls are separated by internodes of some length, and consist of as many as twenty lanceolate free leaves, which are atnbsp;first straight and spreading, but afterwardsnbsp;bend geniculately upwards, while the elongatednbsp;apical portions overlap one another like thenbsp;tiles of a roof. At the bend they show on the dorsal side a round ornbsp;ridge-like emergence projecting downwards. The sporangiophores arenbsp;inserted immediately above these sterile whorls and are axillary; theirnbsp;solid stalk expands into a large covering plate, from the inner side ofnbsp;which are suspended four sporangia (Fig. 46, 3).

The most important of the species known to us in good and clear impressions is Palaeostachya elongata, PresH, from the coal-producingnbsp;mountain country of Bohemia (Fig. 46, i and i). The original specimennbsp;in the Museum at Prague shows a much divided branch-system, composednbsp;of members with the striation of Calamitae and bearing numerous elongate-

'� Weiss (6), t. 3, f. II, and Sterzel (3), t. 28, ff. 2-4. nbsp;nbsp;nbsp;� Sternberg, Graf von (1), Parts 5-8,

t. 15, ff. 1-3. nbsp;nbsp;nbsp;^ Renault (5), t. 2, and (2), vol. ii, tt. 18, 19.nbsp;nbsp;nbsp;nbsp;� Weiss (6), p. 108; t. 15.

cylindrical and somewhat narrow spikes. Another fragment from the Myslowitzer Wald in Upper Silesia referred by Weiss ^ to this genus is innbsp;a less perfect state of preservation. The leaf-whorls are formed of many,nbsp;perhaps twelve, narrow-lanceolate free members which do not touch onenbsp;another laterally. They seem at the first glance to have obcordate sessilenbsp;sporangia in their axils; but in many of them may be seen a verticalnbsp;median strip of tissue running to their apex, which is explained bynbsp;Weiss to be the sporangiophore and which comes out most plainly in thenbsp;Myslowitz specimen. If this is the true explanation, as it probably is,nbsp;then there is in this case no umbrella-like apical expansion. There arenbsp;some doubts respecting the number of the spores; from the drawings itnbsp;might be concluded that there were two median spores ; but Weiss considers it possible that they were as usual developed in fours.

Of Palaeostachya .Schimperiana^ we can only conjecture that it belongs to the genus. It is a large long cylindrical spike of considerable thicknessnbsp;and with the habit of the plant usually known in the literature asnbsp;Macrostachya, Schpr. It appears in Weiss� � earlier publication as Macro-stachya Schimperiana. This spike which comes from Saarbriicken and isnbsp;inclosed in gray argillaceous sandstone is broken through longitudinally,nbsp;and shows the axis and the sporangiophores in the axils of the leavesnbsp;in the form of strips of coal, the latter as very fine strokes.

The spikes also which are supposed to belong to the genus Huttonia have only been found up to the present time in the form of impressions.nbsp;In habit they are extremely like the large impressions of Microstachya,nbsp;so that it is not easy to distinguish the two without a knowledge of the internal structure. The only species certainly determined as belonging to thenbsp;genus, Huttonia spicata, a well-known fossil first described by Sternbergnbsp;appears unfortunately to be rare, having been found hitherto according tonbsp;Weiss only in Bohemia and near Eckersdorf in Lower Silesia. Goodnbsp;figures are given in Schenk� and Weiss�, the older ones being reproducednbsp;in these authors and also in Schimper�. I have never myself had opportunity for minute examination of this form, and I therefore keep to Weiss�nbsp;statements, which however notwithstanding the careful studies on whichnbsp;they are based are still of rather fragmentary character. The sporangiophores for instance are known only from vestiges of remains, which arenbsp;found on the longitudinal fracture of the spike and which spring from thenbsp;axils of the leaf-whorls. These whorls are composed of numerous, thatnbsp;is of from sixteen to twenty, free lanceolate members which narrow upwards into subulate extremities, and which from the partial overlapping of

' Weiss (5), t. 22, f. 15. nbsp;nbsp;nbsp;2 Weiss (6), p. 105 ; t. 5, and (5), p. 271; t. 21, f. 8.nbsp;nbsp;nbsp;nbsp;^ Weiss

(1), p. 122 ; t. 18. nbsp;nbsp;nbsp;� Sternberg, Graf von (2),nbsp;nbsp;nbsp;nbsp;� Schenk (2), t. 41, ff. i, 2.nbsp;nbsp;nbsp;nbsp;� Weiss

(6), t. 13, f. 4, and t. 14, and (5), t. 21, f. 9. nbsp;nbsp;nbsp;� Schimper (1), t. 17.

their margins often appear to unite into a sheath. But close underneath each leaf-whorl is a disk-shaped plate, the margin of which, though verynbsp;imperfectly preserved, is seen to be divided into obtuse lobes. Whethernbsp;this object really represents a free sheath, or whether the lobes spring asnbsp;duplicatures from the dorsal side of the single leaves in a similar mannernbsp;to that observed in Calamostachys mira or Palaeostachya gracilis, Ren.,nbsp;are points on which Weiss himself does not speak very decidedly. Fromnbsp;Schenk�s figures cited above, especially from the first of them, we shouldnbsp;perhaps incline to the latter supposition.

Besides the remains of fructifications which have been discussed at length in the preceding pages there are still a considerable number ofnbsp;similar objects, which are described in the literature under a great varietynbsp;of names. So far as their inner structure is known, they are allied to thenbsp;types of Calamostachys and Palaeostachya. We must not attempt tonbsp;consider all these remains' one by one ; we can obtain nothing either fromnbsp;them or from the Macrostachyae or Paracalamostachyae, of which we knownbsp;the habit only, that can in any way add to our knowledge. Two of them,nbsp;which were found attached to their vegetative parts, will have to be noticednbsp;again presently from this point of view; here we need not go further intonbsp;them. One or two remains of impressions of very doubtful character may,nbsp;however, be mentioned here for completeness sake. These are Volkmannianbsp;pseudosessilis ^ and the analogous form Annul aria brevifolia^, then Volkmannia effoliata� and lastly Volkmannia Morrisii^. A form, which mightnbsp;be suitably named Paracalamostachys has been described by G�ppert asnbsp;Aphyllostachys lugleriana. It would only be of interest, if, as G�ppertnbsp;supposes, it really came from the Lias. But since it is not certainly knownnbsp;where the specimen, which is in the Museum at Breslau, was found, thoughnbsp;it is said to have been picked up near Engern in Hanover, and might verynbsp;well come from the Coal-measures of Westphalia, as G�ppert himself intimates after all, we need not for the present devote any attention to it.

It remains still to notice a few essentially abnormal fructifications, mentioned before as anomalous forms, of which the most important andnbsp;best-known is Cingularia typica� (Fig. 47). This is a very remarkable fossil, found up to the present time, as far as I know, only atnbsp;Saarbr'ucken and St. Ingbert, but not infrequent in those localities andnbsp;occurring in seams of very different description. The long slender spikesnbsp;have a thread-like striated axis, with sterile and fertile whorls spreadnbsp;out quite horizontally and closely approximated to one another in pairs.nbsp;In each pair of whorls the upper member is sterile, the lower fertile; the

internodes are considerably elongated between the pairs. The leaf-whorl forms a horizontal sheath-plate, which is prolonged outwards into a largenbsp;number of lanceolate sharply pointed teeth. In contrast to all othernbsp;known kinds of Calamariae, the fertile whorl does not consist of separatenbsp;free umbrella-like leaves, but forms a connected circular sheath, independent though inserted on the axis close beneath the sterile whorl,nbsp;and having its somewhat deeply incised margin composed of wedge-shaped almost truncated lobes. Twelve of these lobes were counted

on a perfect whorl figured by Weissk Stur�s reconstruction, in which the lobes are not united at the base into a' sheath, must be corrected bynbsp;the above description. Each of the lobes is slightly bipartitely mar-ginate along a furrow which follows the median line, and is also divided bynbsp;a distinct transverse fold into an anterior and a posterior segment. On thenbsp;under side of each of the somewhat rectalngular areolae, formed by the intersection of the median furrow and the transverse fold, is a circular attachment-scar, which when the preservation is good is surrounded, as the sun by its rays,nbsp;with a delicate radial striation. The sporangia, four in number, were attached to these scars : they were found so connected in a specimen figurednbsp;by Weiss in which they hang vertically downwards from the under side

of the lobes of the sheath. They are peculiar in form, being a little compressed on one side. They are comparatively very large and are marked with a very fine striation in an oblique direction, which may be distinguishednbsp;even when they have fallen from the sheath which bore them and lienbsp;about beside and between the specimens, as is usually the case. Thenbsp;positions of the entire spikes in the stone are peculiar; they either lienbsp;horizontally on the surface of the beds, or, which is the more common case,nbsp;the slender axis is vertical to the beds, and the separate whorls are spreadnbsp;out flat on their surfaces. This would imply that the whorls were stillnbsp;stiff and rigid when they were buried. Though the spikes usually occurnbsp;very many together�I found a block of stone on the refuse-heap of thenbsp;Skalley mine which contained hundreds of them�yet the vegetative organsnbsp;which bore them are scarcely known ; a few specimens only have beennbsp;found, in which one or two spikes were attached to bits of articulatednbsp;striated branches resembling those of Calamitae^. I did not succeed innbsp;finding more of the same kind on the occasion referred to, though I lookednbsp;for them very carefully. Brongniart�s^ Equisetum infundibuliforme maynbsp;also belong to Cingularia. Only the sterile whorls are disclosed by thenbsp;fracture. I have seen specimens in Goldenberg�s collection at Saarbriicken,nbsp;which were evidently Cingulariae and which answered to Brongniart�s figure.

There is another quite peculiar fossil, supposing the reconstruction of it to be correct, which has been described by Williamson ^ and which wasnbsp;found, unfortunately only in a small fragment, as a petrifaction in anbsp;calcareous nodule from Lancashire. Its hollow axis shows the usualnbsp;peripheral lacunae which answer to the primary bundles, but here theynbsp;are curiously approximated to one another in pairs. According to Williamson�s account there was only one kind of whorl, in which the leavesnbsp;were united below into a somewhat concave plate and prolonged abovenbsp;into numerous erect free apices. The sporangiophores are supposed tonbsp;have been placed on the inner side of the ba.sal plate of the leaf-whorl,nbsp;and the sporangia to have been attached to them. But the small sizenbsp;and the imperfect state of this fossil give room for many doubts.

The genus Bowmanites, Binney, is also founded on some problematical remains. The type is Bowmanites cambrensis^, which was found in somenbsp;clay iron-stone workings near Hartypool in South Wales, and appears fornbsp;the most part only in the form of a mould. The chief portions of it arenbsp;lost; two which were saved are in Binney�s collection, which during mynbsp;many visits to Manchester was always inaccessible. The figures too arenbsp;partly from sketches by the former owner of the specimen, Mr. Bowman.nbsp;The compact cylindrical spike surrounded by long erect leaf-tips is attached

to the extremity of a branch with striated internodes and somewhat swollen nodes, and showing distinctly the characters of Asterophyllitae.nbsp;According to the sketch of a longitudinal section by Mr. Bowman reproduced in Binney^, the spike would appear to consist entirely of whorls allnbsp;like one another. In the interval between every two whorls is a rownbsp;of roundish bodies, which Binney explains as macrospores, but whichnbsp;Weiss^ considers to be sporangia. It is in favour of the correctness of thenbsp;sketch alluded to, that Weiss ^ figures a fossil of exactly similar structure,nbsp;Bowmanites germanicus, Weiss, from the Gustav mine near Schwarzwaldaunbsp;in Lower Silesia. Whether Volkmannia Dawsoni^, which will be describednbsp;presently, belongs, as Weiss thinks, to the group which we are considering,nbsp;is in my opinion very doubtful. The structure of the axis is not in favournbsp;of its belonging to Calamarieae. The same structure might also have beennbsp;present in well-ascertained Bowmanitae, and remove them from Calamarieae ; but only fortunate discoveries can enable us to determine these points.

Lastly, there are a few very imperfectly known fructifications which should be mentioned, and which, though differing to some extent fromnbsp;each other, have been referred by various authors to Archaeocalamites.

There is first of all a series of doubtful impressions known as Pothocites, Paterson from the lowest beds of the Carboniferous formation of Scotlandnbsp;(the Calciferous limestone series), which Kidston� has sought to place withnbsp;Calamarieae. The older literature of these objects has also been collectednbsp;by this author. The remains in question are long spikes on the extremitiesnbsp;of branches like those of Asterophyllitae, and bearing short leaves. Thenbsp;spikes are divided by constrictions into cylindrical members, and innbsp;each constriction is a sterile leaf-whorl composed of short filiform freenbsp;leaves. The only quite perfect known specimen, Pothocites Grantoni,nbsp;Paters.� has eight cylindrical members. These members are alwaysnbsp;much compressed and converted into a tolerably thick compact covering of coal, and appear to consist of numerous small ovoid bodiesnbsp;(sporangia ?) arranged in longitudinal and transverse rows. Besides thesenbsp;bodies there are also peculiar star-shaped figures with from four to fivenbsp;rays, also disposed in longitudinal rows and belonging to the surface ofnbsp;the member, so that they are not visible when that is badly preserved;nbsp;the rays have raised margins'^. Kidston considers these stars to benbsp;sporangia, but I must doubt this, as I have already intimated ; but thoughnbsp;I have had opportunity of examining several specimens, I am unable tonbsp;offer any other explanation of them. Again Stur� sees in Asterophyllitesnbsp;spaniophyllus, Feistm., described by O. Feistmantel� from the Carboni-

� Binney (1), ii, t. 12, f. 3. nbsp;nbsp;nbsp;� Weiss (5), p. 200.nbsp;nbsp;nbsp;nbsp;� Weiss (5), p. 201; t. 21, f. 12.

� Williamson (9). nbsp;nbsp;nbsp;= Kidston (4).nbsp;nbsp;nbsp;nbsp;� Kidston (4), t. 12, f. 13.nbsp;nbsp;nbsp;nbsp;� Kidston (4), t. 9,

3-5. nbsp;nbsp;nbsp;* Stur (6).nbsp;nbsp;nbsp;nbsp;� O. Feistmantel (5), p. 498 ; t. 14, f. 5.

ferous limestone of Rothwaltersdorf in Silesia, a branch of Archaeocalamites radiatus bearing terminal fertile spikes, and known by its long dichotomouslynbsp;divided leaves. He gives a new figure^ of the impression of the spike,nbsp;which unfortunately is in a very bad state of preservation. He believesnbsp;that he recognises in it a spike composed of numerous sporophylls interrupted from time to time by a sterile leaf-whorl. This view is to somenbsp;extent in accordance with the arrangement of the parts in Pothocites, andnbsp;it reminds us of the structure of the fructifications, perhaps belongingnbsp;to Phyllotheca, which was described above on p. i8i. Lastly, Renault^ innbsp;a preliminary communication has described fructifications, which he saysnbsp;that he has found in a good state of preservation and still attached to theirnbsp;branches. The more detailed account of these objects will perhaps thrownbsp;more light on them. According to his statements, the � male fructifications of Bornia � are spikes bearing sporophylls only. These sporophylls,nbsp;from eight to ten in a whorl, are umbrella-shaped, and as usual bear fournbsp;sporangia. They come from the anthracite-beds of La Vend�e, and, asnbsp;Renault distinctly says, have been already figured by Grand� Eury�. Thenbsp;figure in the text of Grand� Eury�s work does not indeed appear to me tonbsp;answer too well to the description. We are not told whether the spikesnbsp;which Grand� Eury found attached to his Bryon (see on p. 323) are referred,nbsp;as they might be, to these forms.

It would be very important to know what were the organs of vegetation belonging to each of the fructifications in the rich series whichnbsp;has now been described. On this point unfortunately there are but fewnbsp;quite certain facts to which we can appeal. It has been ascertained innbsp;the case of a number of spikes, as appears from the foregoing remarks,nbsp;that they are attached to leafy branches resembling those of Asterophyl-litae, but this leaves us still in ignorance in almost every case of thenbsp;stems to which the leafy shoots belonged. Conjectures on this subjectnbsp;there are indeed in plenty, based more or less on personal persuasion fornbsp;which no exact reasons can be given, but such views cannot be discussednbsp;here to any profit because of the instability of their foundations. In thenbsp;following remarks therefore I shall mention only those cases in whichnbsp;spikes of known organisation have been found in direct connection withnbsp;vegetative parts capable of being determined, for only these can serve as anbsp;basis for further research. The first that should be mentioned are Cala-mostachys tuberculata, Weiss, and C. calathifera, Weiss, both of which werenbsp;found attached to leafy branches of Annularia longifolia and A. sphenophyl-loides in impressions near Lugau in Saxony. SterzeH has illustrated thenbsp;connection between the two latter forms by means of excellent figures.

which are wanting in the case of the others, but we have meanwhile his express testimony Both leafy branches and fertile spikes were foundnbsp;together attached to rather thick flattened stalks covered with a thin rindnbsp;of coal, exactly in the manner represented by Weiss Now Weiss hadnbsp;already compared the piece of stem in his specimen, which has an annularnbsp;swelling at the upper node, with the doubtful Equisetides lingulatus (seenbsp;above on p. 178); Renault� too, though not as the result of more searchingnbsp;examination, had referred this form to Annularia longifolia, and Schenk ^ onnbsp;the strength of the specimen figured had assented though not unreservedly tonbsp;this view. And now it receives fresh support from Sterzel. Sterzel was notnbsp;able to distinguish a specimen before him of the remains in question fromnbsp;his Annularia-stalks. He says that there should be eight fertile spikes atnbsp;the nodes, and their sporophylls should show the customary structure ofnbsp;Calamostachys. Weiss� again has found a quite normal Calamostachysnbsp;in direct connection with Calamites ramosus and its leaves, that is withnbsp;Annularia ramosa. Another colossal spike with the habit of Palaeostachyanbsp;Schimperiana and similar Macrostachyae, which has also been proved tonbsp;belong to Calamostachys, Calamostachys Solmsi was found by myselfnbsp;connected with a Calamitina in the Skalley mine at Saarbriicken. Thenbsp;block of stone was of huge size, and contained in its different planes ofnbsp;stratification a large number of spikes a foot long and converging in tuftsnbsp;towards one point. It is true that the connection of the tuft with the impression of Calamitina was not perfect so that the case cannot be takennbsp;as quite certainly established, though personally I am fully convincednbsp;that it is to be trusted. Lastly, Palaeostachya arborescens, Weiss, anbsp;form so near to P. Schimperiana above described that it perhaps coincidesnbsp;with it, has been found in connection with Stylocalamites arborescens,nbsp;Weiss To the literature cited by Weiss may be added the figure innbsp;Lesquereux as a fine specimen illustrating the connection in correspondingnbsp;manner. The specimen is named in the text'� Volkmannia crassa, Lesq.nbsp;It is characteristic of this form that the large cylindrical spikes, which arenbsp;borne in large numbers on quite short thin branchlets, are every one ofnbsp;them directly attached to the nodes of the stems of Calamitae. There arenbsp;leaves to be seen in one of Weiss� figures which may perhaps have belonged to the stem. Such leaves are depicted in Lesquereux also, thoughnbsp;they are shorter and apparently still attached.

To the foregoing statement of facts serving as a basis for further conclusions, it will be necessary to add a few words on the points of view

which may be made use of for or against such a division of Calamariae into Calamitae and Calamodendrae, as is desired by the school ofnbsp;Brongniart. I may say at once that it cannot in fact be strictly provednbsp;that all forms of Calamariae belong to one another in the sense of Williamson, Stur and Weiss, but that on the other hand the reasons of thenbsp;French authors for separating them into two quite different series are innbsp;my opinion far from sufficient for that purpose. It will be best therefore,nbsp;till stronger proofs can be alleged in support of the latter theory, to keep tonbsp;the more simple view of the English and German authors, treating thenbsp;whole matter at the same time as an open question.

Of the arguments which must be urged against Brongniart and Renault, there are two of great and special importance.. First it mustnbsp;be asked which of the Calamitae are supposed to have borne gymno-spermous fructifications, since we find archegoniate fruiting spikes on stemsnbsp;and branches of very various kinds, on Stylocalamitae (Palaeostachyanbsp;arborescens), on Calamitinae (Calamostachys Solmsi), on Eucalamitaenbsp;(Calamostachys ramosa) and also on Annulariae (Calamostachys tubercu-lata and C. calathifera). It is true that Renault has recently endeavourednbsp;to meet this difficulty by turning the spikes into male flowers. But thisnbsp;does not seem to me to have been a happy idea ; it does not appear whynbsp;this interpretation should not be extended to all spikes, and thus we shouldnbsp;have all the Calamariae united into one group, only under a different setnbsp;of a.ssumptions and with a different terminology.

On the other side it is to be observed that all known stems of this group were capable of growth in thickness. If there were other Calamitaenbsp;which had no such power of growth, it must certainly seem very strangenbsp;that they should never have been found in a state of petrifaction. Grand�nbsp;Eury himself cannot help expressing his astonishment at this. He says ^;

� It is, to say the least, surprising that no one has yet met with a Calamite with the structure preserved.� The objection, that they may have allnbsp;perished owing to the more delicate nature of their tissue, cannot benbsp;regarded as sufficient, for in that case the young and slender branches ofnbsp;Calamariae could not well have been preserved, whether we suppose themnbsp;to have belonged to Calamitae or to Calamodendrae. But such branchesnbsp;have been more than once, though not very often, described and figured bynbsp;Williamson^. They show the well-preserved parenchymatous pith, surrounded by a circle of conspicuous primary bundles with large lacunae.nbsp;It may indeed be replied, that in point of fact remains of stems of Calamitaenbsp;have been found with the structure of Equisetae and with no secondarynbsp;growth, and the famous specimens from the Plauensche Grund near

Dresden, figured and discussed by Petzholdt ^ and Geinitz may be cited in proof of this. Petzholdt�s Calamitae are imbedded in grayish whitenbsp;Carboniferous sandstone, and show on the transverse section a centralnbsp;space filled with the stone, and surrounded by a rather thick compactnbsp;envelope of coal. But this layer of coal, itself with a rather irregularnbsp;outline on the outside and on the inside and with many small projectingnbsp;teeth, is cut up by a circle of lacunae filled with the stony matter intonbsp;segments which have the shape of the transverse section of a double T. Inbsp;have myself seen several sections of the kind in Dresden and Strassburgnbsp;from Petzholdt himself, and they appear in his tables well-drawn and truenbsp;to nature. Now he has explained the whole of this structure by thenbsp;direct unaltered preservation of the original state of the stems, and Schimper�nbsp;and others have adopted this view. The lacunae therefore in the rindnbsp;of coal were the vallecular canals, the central space the medullary cavitynbsp;of the Equisetum-like stem. Still the irregular nature of the layer of coalnbsp;must cause some hesitation, and its thickness must seem surprising, if wenbsp;hold to the view that it was produced from the wall of a herbaceousnbsp;hollow stem. And in fact Schenk^, who has submitted these remainsnbsp;to fresh examination, has succeeded in proving that the mass of coal innbsp;it consists entirely of secondary wood, which was torn and broken upnbsp;only in the process of imbedding; that the lacunae are thus in thenbsp;middle of the wood and only represent defective places in it, and thatnbsp;they therefore cannot be compared with the vallecular canals. Thenbsp;specimens are in fact remains of Calamodendron or mixed masses ofnbsp;Calamodendron and Psaronius, which are not in question as regards ournbsp;argument.

The view of Brongniart and his pupils is founded in the main on the petitio principii which will not hear of secondary growth in Archegoniatae.nbsp;But it appears to me that the facts as observed in Lepidodendron andnbsp;Sigillaria, and even in the recent Iso�tes, leave so little foundation for thisnbsp;idea, that it can no longer be employed as a main argument. Thenbsp;points brought forward in support of it, where they have not been alreadynbsp;disposed of, are of little value. Much importance is attributed fornbsp;instance to the difference in the thickness of the rind of coal. But thinnbsp;coverings of coal are formed even when there is only a small amountnbsp;of secondary growth, and we discover how greatly the amount variednbsp;by examining large collections of sections. No one of the many differences which Grand� Eury ascertained in the underground organs ofnbsp;our plants is of such a kind as to imply more than a generic, or shall

we say a family difference. All that we learn then in this way is, that in Calamariae we are dealing with a more copiously differentiated seriesnbsp;of forms than appears to be the case at first sight. Hence so long asnbsp;the existence of female flowers or seed of Calamodendrae is not clearlynbsp;demonstrated, and so long as the difficulties here discussed cannot benbsp;quite removed, we shall be obliged to maintain the sceptical positionnbsp;previously described.

XIV.

The Sphenophyllae are members of one of the most remarkable among the leading genera of the Middle and Upper Coal-measures. They do notnbsp;pass beyond the Lower Rothliegende, in which they have been found atnbsp;Autun, and it is doubtful whether the species described from older depositsnbsp;belong to the group. This is especially the case with Sphenophyllumnbsp;tenerrimum, Ett.^ from the Culm, the beds of Ostrau and Waldenburg,nbsp;which may even be a Calamites, and be parallel with Archaeocalamitesnbsp;radiatus, and still more with the rather obscure and dubious Devoniannbsp;remains which Dawson'quot;* named Sphenophyllum antiquum.

The genus, owing to its striking appearance, has been repeatedly figured by the old authors; a copious collection of the older literature andnbsp;of the descriptions of the several species is given by Coemans and Kickx�.nbsp;The slender stems, which in the impressions are simply a thin rind of coal,nbsp;are articulated, and bear at the nodes leaves in whorls, and branchesnbsp;standing singly and according to the statements of authors in the axils ofnbsp;the leaves. The stems are usually marked by rather strong ridges andnbsp;furrows, which always run unaltered and uninterrupted over the nodes.nbsp;Each whorl consists of at least six leaves, often of more, and in that case thenbsp;number is always a multiple of six, beingtwelve, eighteen, or even twenty-four.nbsp;On this point I find that all authors virtually agree. The single sessile leafnbsp;broadens and becomes wedge-shaped from a narrow base, and is obtuselynbsp;rounded at the anterior margin and sometimes toothed (Sphenophyllumnbsp;Schlotheimii, Brongn., S. emarginatum, Brongn.), or else it is repeatedlynbsp;and dichotomously divided with more or less deep incisions into broader ornbsp;narrower points. The lamina of the leaf is traversed by simple unconnectednbsp;nerves of equal size, which bifurcate once or repeatedly, and are slightlynbsp;divergent. According to Schenk^ one nerve only enters the base of thenbsp;leaf. This is certainly true of the form which he has described (Sphenophyllum emarginatum, Brongn., var. truncatum, Schpr), but I should doubt

its being the same in all species for reasons to be discussed presently. How far the degree of division and incision of the lamina can be employednbsp;in determining species requires further consideration, for Coemans andnbsp;Kickx^ state that the stems of several species have deeply incised leavesnbsp;below, and almost entire leaves above, in the manner of our living Batrachiae.nbsp;If they mean to infer that Sphenophylleae were aquatic plants, their view isnbsp;opposed by both Schimper^ and Schenk who appeal to the anatomy of thenbsp;stem. I prefer not to give a decided opinion on this point for the present.nbsp;As regards the heterophylly, which Weiss ^ also regards as an establishednbsp;fact, the only instances of it which I can find are the branched specimensnbsp;figured in Germar� and Schenk�; and in these it is only the main axisnbsp;which bears incised leaves, those of the lateral branches are alike and havenbsp;entire margins, so that the comparison with Batrachiae is not exact.

As soon as the wedge-like form of the leaves is disguised by the copious and deep incision of the anterior margin, it necessarily becomes difficultnbsp;and sometimes quite impossible to distinguish the remains of Sphenophylleaenbsp;with any certainty from Asterophyllitae and Annulariae. To be convincednbsp;of this, we have only to examine the figures of Sphenophyllum angusti-folium, Germ, in Schenk'^. Gerrnar�s� figure of the same species is not tonbsp;be distinguished from an Asterophyllites ; it may even be doubted whethernbsp;it belongs to Sphenophylleae. It is necessary to insist upon this pointnbsp;because of its importance as showing, in opposition to Williamson�s resultsnbsp;which will be considered further on, that in impressions where the anatomynbsp;cannot be examined no certain line of distinction can be drawn between thenbsp;two genera, if Asterophyllites may be called a genus. We must not losenbsp;sight of this in judging of Stur�s Asterophyllites mentioned above on p. 314,nbsp;from which a branch of Sphenophyllum is growing. It is possible thatnbsp;some of the remains which we should now call Asterophyllitae will ultimately prove to be Sphenophylleae. We have a case already in Spheno-phyllum teperrimum, Ett. which gives room for much doubt. This slendernbsp;diminutive plant has been figured and described by Stur � with his usualnbsp;care. Its furrowed stems bear whorls of dissimilar once or twice dividednbsp;leaves, in which the incisions follow the nervation in such a manner, thatnbsp;each point is traversed only by a median nerve. Where the whorls lienbsp;spread out in the plane of stratification, the number of leaves has beennbsp;found to vary; I find the numbers nine, ten, eleven, and twelve given innbsp;Stur, which does not quite agree with the regularity observed in genuinenbsp;Sphenophyllae, though I do not consider the point to be very important.nbsp;But this specirnen might quite as well be compared with Archaeocalamites,

in which the leaves are of like form, but of somewhat greater length, though we must not omit to say that fructifications occur at the same spotnbsp;which very probably belong to the stems in question, and which, thoughnbsp;imperfectly preserved, yet show some resemblance to those known to havenbsp;belonged to Sphenophyllum. This is why the plant is considered in thisnbsp;place. If it really belongs to our group, we shall be able to follow the typenbsp;of Sphenophylleae much farther back than the limits usually assigned tonbsp;it. An equally strong splitting of the repeatedly forked leaf-blade isnbsp;figured by Zeiller ^ in the plant which he has named Sphenophyllumnbsp;saxifragaefolium.

As abnormal form, whose connection with the group appears not to be entirely free from doubt, may be mentioned first, Sphenophyllum Thoniinbsp;hitherto found only in the highest beds of the Carboniferous formationnbsp;at Ilmenau and in France. According to Zeiller� this plant is distinguishednbsp;essentially from other species of the genus only by the size of its parts, andnbsp;by the strength and prominence of the nervation of its leaves, in which thenbsp;anterior margin is slit up into narrow fringe-like teeth. More decidednbsp;differences appear in the doubtful remains described as Trizygia speciosa*,nbsp;which, as belonging to the Damuda group of the Lower Gondwana systemnbsp;of India, comes from a higher level than that of the Carboniferous formation,nbsp;perhaps from the Trias. O. Feistmantel� has given a description andnbsp;figures of this plant, and has also collected the literature. I have seennbsp;specimens only in the Botanical Department of the British Museum. Thenbsp;thin filiform stems which are swollen at the nodes bear six-leaved whorls,nbsp;which appear to be regularly superposed. The roundish wedge-shapednbsp;leaves in each node are arranged in three pairs, two of which are exactlynbsp;opposite to one another, while the third, formed of much shorter members,nbsp;occupies the interval between them on one side. The arrangement of thenbsp;leaves is thus unilateral, and there is in all the whorls a broad intervalnbsp;opposite the smaller pair of leaves. Branching has, as far as I know,nbsp;not yet been observed on the plant. The genus Sphenoglossum foundnbsp;in the blue shales of the apparently Triassic coal-field of Deep River innbsp;North Carolina, and described by Emmons�, is less known, and as thenbsp;verticillate broadly wedge-shaped leaves are in fours it can scarcely belongnbsp;to our group.

Here again it is to Renaultmore than to anyone else, and next to him to Williamson�, that we owe our knowledge of the inner structure ofnbsp;the Sphenophyllae. This structure has proved to be highly remarkable,nbsp;and not directly comparable with that of any other plants. A primary

� Zeiller (3), t. i6i, ff. 3, 4, 6. nbsp;nbsp;nbsp;^ Mahr (1), t. 8.nbsp;nbsp;nbsp;nbsp;= Zeiller (3), p. 34, t. 161, f. 9.

* Royle (1), t. 2, fif. I-}'. nbsp;nbsp;nbsp;^ Pal. Inci. ser. XU, Pt. II, p. 69, tt. ii, 12.nbsp;nbsp;nbsp;nbsp;' Emmons (1).

� Renault (2), vol. ii, p. 91, and vol. iv, Introd., also (16) and (20). nbsp;nbsp;nbsp;* Williamson (1), V and ix.

triarch xylem-strand, the only one which appears at first, is afterwards inclosed by a secondary growth of quite peculiar structure, after thenbsp;manner observed in growth in thickness in roots. These stems appear,nbsp;according to Williamson, to be comparatively rare in the calcareous nodulesnbsp;of Lancashire, but they are much more abundant in those of Langen-dreer, from which I have a considerable number of specimens before me.nbsp;In Autun also, and especially in the pebbles of Grand� Croix, they havenbsp;been repeatedly found by Renault and Grand� Euryk The material fromnbsp;Grand� Croix has enabled Renault^ to prove that the stalks in questionnbsp;have really belonged to Sphenophyllum. A plane of fracture in a favourablenbsp;direction showed him an undoubted leaf of that genus, with the characteristicnbsp;transverse section of the stalk in connection with it. He has repeatedlynbsp;figured � transverse sections of the stalks, which are surrounded by thenbsp;leaves still in the original position (Fig. 48, 2).

If we first examine the young stem as yet without growth in thickness, we find it to consist simply of a thick rind inclosing the three-winged bundle.nbsp;If the transverse section has exactly hit the node, we also get the leaf-trace-strands passing through the rind and running outwards almost at a rightnbsp;angle to the axis. In the leaf-trace may be distinguished an inner bast-layer, which in such young stems is almost always destroyed and replacednbsp;by an annular vacant space, and outside the bast Renault ^ maintains thatnbsp;he has sometimes found the protecting sheath consisting of thick-wallednbsp;elements closely united laterally with one another. The sheath is surrounded by a thick mantle of primary cortical parenchyma, the hypodermalnbsp;cells of which are said to be fibre-like. The form of the transverse sectionnbsp;of this cortex is peculiar (Fig. 48, 2). Generally three-angled approachingnbsp;to circular in shape, it shows on the outer side at each angle a longitudinalnbsp;furrow which divides the angle into two ribs lying in pairs side by side.nbsp;Each pair of ribs lies in front of one of the surfaces of the xylem-strand,nbsp;the flat sides between the ribs are in front of its angles, and consequentlynbsp;the outer surface does not repeat the form of the central strand. Thenbsp;section is less frequently simply cylindrical �, without any angles and furrows.nbsp;As the ordinary impressions all belong to the outer surface, we see againnbsp;how little comparison there can be between any trace-points visible on itnbsp;and the prominences on the substance which replaces the pith in Calamitae,nbsp;though such a comparison has been attempted by Stur�. The centralnbsp;xylem-strand consists chiefly of tracheides with bordered pits, which arenbsp;broadest in the middle and gradually diminish in size towards the angles,nbsp;and here too are replaced by scalariform vessels. At the extreme edge of

Grand� Envy (1), p. 50. nbsp;nbsp;nbsp;Renault (20), p. 288, t, 9, f. 12.nbsp;nbsp;nbsp;nbsp;� Renault (16), t. 4,

ff. 5, 6 ; (20), t. I, f. 2 ; (2), vol. ii, t. 15, f. 2. nbsp;nbsp;nbsp;¹ Renault (2), vol. iv, Introd. t. A, f. 2.

each wing are two weak initial strands, lying close together and composed of spiral and annular cells with threads that may be unwound, and as therenbsp;is usually a small gap in the tissue between them, they project into it andnbsp;form two teeth at the angle of the xylem-strand. The entire xylem-strandnbsp;is usually uniform, though in the young state its tracheal elements wouldnbsp;appear to be accompanied with a parenchyma, which may be supposed tonbsp;be destroyed at a later period, as the tracheides increase in diameter though

probably not in number Renault ^ has found a macerated silicified stem in which the xylem-strand, by destruction of the more central tissue, isnbsp;broken up into three curved rows of vessels with their convexity turnednbsp;towards each other, and with their six free extremities formed of six initialnbsp;bundles. He supposes therefore that the whole body was originally composed of three separate diarch strands. Van Tieghem� indeed thinks thatnbsp;it was developed from six separate monarch strands united together in pairs,nbsp;and having their initial bundles on the outer side.

and plausible; but as there can be no certainty in the matter without a knowledge of the development, we do not gain much by these explanations.

The wood-strand goes through the nodes, as Renault showed, without perceptible change. Here a leaf-trace of a single strand emerges at oncenbsp;and attaches itself to each of the initial bundles. The traces which thusnbsp;arise in pairs at the corners (Fig. 48, 4) pass through the rind in a horizontalnbsp;course and with slight divergence, and usually branch dichotomously whilenbsp;still inside it. If now we may assume that a single bundle enters the leafnbsp;in all the forms, as Schenk has shown to be the case in one of them (seenbsp;above on p. 343), the number of the leaves may be concluded directly fromnbsp;the structure of the transverse section of the node. The node figured bynbsp;Renault^ and given here (Fig. 48, 4) must thus have borne twelve leaves,nbsp;those represented by the same author in a previous publication^ must havenbsp;had eighteen. But the difference in their outline shows that these sectionsnbsp;belong to different species, in which there might very well be distinctions innbsp;this direction, such as are in fact alleged by Grand� Eury One thingnbsp;however is by this means absolutely proved, as Renault has pointed out,nbsp;namely, that the leaves in consecutive whorls were superposed. And if thisnbsp;can be directly shown in Trizygia speciosa, and its leaves are moreovernbsp;combined in pairs, it appears to me that we have no slight proof that thenbsp;plant belongs to the present group. The unequal distribution of the leavesnbsp;round the periphery of the nodes will be accompanied, as might perhaps benbsp;expected, by bilateral symmetry in the structure of the central strand.

Pieces of young stems showing only the primary structure are however rare; specimens with secondary wood more or less developed are muchnbsp;more common. Van Tieghem�s� charge against Renault, that he hasnbsp;mistaken the nature of this wood, seems to me, as so put, to be unfounded;nbsp;Renault has described it correctly, only he has preferred to use a neutral expression which does not prejudge anything, and to call it a �sheath ofnbsp;punctate tubes.� The woody body in question consists then chiefly of broadnbsp;tracheal elements, having the form of four-sided prisms with a regularlynbsp;square transverse section, and with the vertical and radial angles replaced bynbsp;narrow planes of truncation. On the tangential section therefore they arenbsp;seen as continuous vessel-like tubes, in the radial direction they have thenbsp;appearance of being made up of many members set one on another, andnbsp;looking like the component members of normal vessels (Fig. 48,3). Whethernbsp;they are really of this kind has not yet been ascertained ; there is nonbsp;appearance of transversal parting walls, but these might have perished bynbsp;maceration before petrifaction. On the other hand, no pointed extremitiesnbsp;pushed in between one another, such as are usual in tracheides, have ever

� Renault (20), t. 7, f. 3. nbsp;nbsp;nbsp;� Renault (16), t. 4, ff. 3, 4, and t. i, f. 5. Grand� Eury (1), p.

* Renault (2), vol. iv, Introd. p. 29. nbsp;nbsp;nbsp;* van Tieghem (3), p. 173.

been observed. We can scarcely hope to give a decisive answer in the case of fossil remains to a question which is sometimes so difficult in dealingnbsp;with living material. These elements are arranged on the transverse sectionnbsp;of the stem in regular radial rows, and at the same time in concentricnbsp;successive layers; they touch one another in the four chief planes which arenbsp;their lateral boundaries. But the truncation of their angles causes thenbsp;formation between them of irregularly four-angled spaces, which, as thenbsp;radial angles suffer a similar truncation, communicate with one another innbsp;this direction and form a more or less regularly arranged system. Thisnbsp;system is seen, when the preservation is good, to be filled with small-cellednbsp;parenchyma, the elements of which are radial in radial sections, in othersnbsp;vertical and somewhat elongated'. This tissue differs essentially from thenbsp;medullary rays of other plants in arrangement and distribution, but may benbsp;its equivalent as regards function.

The bays in the originally thi'ee-winged woody body are soon filled in by a large development of secondary tissue. But this is not brought aboutnbsp;in the present case by the introduction of a larger number of tracheides;nbsp;the concentric layers are always and everywhere maintained with unvarying regularity (Fig. 48, a, 4). Only the breadth of the elements changes,nbsp;and is much greater in the portions of the secondary growth in front of thenbsp;bays than elsewhere. It is peculiar that there is no gradual passage fromnbsp;the one to the other, but that the small-celled portions in front of thenbsp;angles, which increase in breadth towards the outside and have parabolicnbsp;inwardly convex bounding lines, are in quite sharp contrast with the others.nbsp;In this way the primary strand is surrounded by a closed mantle of anbsp;secondary formation of tracheides, which proceed from an external cambialnbsp;zone and pass layer by layer into the permanent state. Specimens arenbsp;often found, in which one layer only (Fig. 48, a) or a few are developed ^nbsp;and these are then always equally and fully developed all round. In oldernbsp;stems on the contrary layers are often observed which have not reachednbsp;their complete development in every part, and here it looks as if this development began in the area of the small-celled corner-portions. Thenbsp;growth in thickness may not last very long. In the transverse sectionsnbsp;figured by Renault I find the largest number of concentric layers of woodnbsp;to be eleven, and he says� that one stem which he has not figured hasnbsp;fifteen. Williamson^ indeed has figured a transverse section with a greatnbsp;many more layers, but with Renault I question most decidedly whether thisnbsp;preparation belongs to the group which we are considering. Its secondarynbsp;wood of scalariform tracheides shows quite normal medullary rays of anbsp;single row of cells, such as do not occur in Sphenophyllum. We may

� Renault (20), t. 7, ff. 2, 3, and t. 9, f. 4. * Williamson (1), v, t. 4, f. 21.

therefore consider it to be a transverse section of a root, but to what plant it belongs is quite uncertain. In the nodes the secondary growth isnbsp;traversed by the leaf-trace-strands, and near each of these is an interspacenbsp;of tubular form filled with a delicate parenchyma.

In some particularly well-preserved specimens Renault ^ has observed the bast in the form of a thin-walled crushed tissue surrounding thenbsp;secondary wood. Single larger lumina in it he considers to be sieve-tubes. Immediately outside the bast is a layer of tissue, which he ^ terms anbsp;�suberous layer corresponding to the protecting sheath of the mass of phloemnbsp;and xylem,� and which he derives from the tangential division of the cells ofnbsp;the protecting sheath. This tissue, with its patelliform or tubular cells innbsp;radial rows as given in Renault�s figure looks in fact very like a periderm,nbsp;and may be a periderm, if Renault�s further statements, which I cannotnbsp;judge of from the material in my possession, are ultimately confirmed. Henbsp;says in effect that in the old piece of stem mentioned above with fifteen layersnbsp;of secondary wood and with the rind removed, there are several of thesenbsp;� couches sub�reuses� present, separated from each other by layers of crushednbsp;bast (� tissu corn�). This, as he distinctly says would mean normal formation of bark. The accompanying figure would ratherlead us to regard thesenbsp;layers of � tissu corn� to be simply layers of sclerenchyma, such as so oftennbsp;alternate in the phellem with the cork-cells. In that case we must regardnbsp;the whole not as rhytidom, but as one connected mass of periderm.

The pieces of stem which come under notice are usually short fragments without their leaves, and commonly even without their rind. Renault however has in two cases succeeded in finding specimens which showed thenbsp;leaves in situ and with their structure preserved. Williamson � also dealsnbsp;with a similar case. Here the stem was imbedded in the stone, and onlynbsp;the longitudinal and the transverse sections could be observed, not the formnbsp;of the lamina of the leaf. Fig. 48, 2 reproduces the drawing in Renaultnbsp;which gives the clearest view of a specimen of the kind. It shows the stemnbsp;surrounded by six four-nerved leaves. Renault � has also given two transverse sections of another species, his Sphenophyllum Stephanense, takennbsp;from a stem at different heights. Only two leaves are distinctly preserved ;nbsp;those in the lower section are three-nerved, in the upper section they arenbsp;replaced by six small one-nerved transverse sections swollen in the middle,nbsp;and answering to the three teeth into which each leaf has meanwhile divided.nbsp;Here too from the position of the leaves there would not have been morenbsp;than six present. In Williamson�s specimen just alluded to the arrangement of the leaves is less clear, because only radial and tangential sections

* Renault (2), vol. iv, Introd. t. A, f. 3 c. ^ Renaiilt (2), vol. iv, Introd. p. 4. nbsp;nbsp;nbsp;� Renault (2),

vol. iv, Introd. t. D, ff. 3, 4. nbsp;nbsp;nbsp;� Renault (21, vol. iv, Introd. p. 13; t. D, f. 4.nbsp;nbsp;nbsp;nbsp;� Williamson

were observed. The leaf-teeth, several of which are combined together in the lower part of the stem, are enlarged in the middle and one-nerved, andnbsp;properly comparable with those of Sphenophyllum Stephanense. Williamson, on account of the deep incisions in these leaves which reach nearlynbsp;to the base, refers his specimen not to Sphenophyllum but to Astero-phyHites, and tries to justify this by comparing the facts of the case withnbsp;the diagnoses of the two genera obtained from impressions. That such anbsp;proceeding is inadmissible is evident from our remarks on p. 344; thenbsp;structure of the stem in this specimen is that observed in acknowledgednbsp;Sphenophyllae and only in them, and is sufficient to prove that it belongsnbsp;to that group. And if Stur' writes: � As far as we know at present it isnbsp;the fact, that the Calamariae show as great differences of anatomical structure in the variously leaved branches of the same individual, as we arenbsp;accustomed to find in living vegetation even in different and very dissimilarnbsp;families,� it is simply from once more overvaluing the results obtained fromnbsp;impressions. For who will venture to say that the supposed Asterophyllites,nbsp;from which the branches of Sphenophyllum grew, had not the same structurenbsp;as Sphenophyllum and was not simply a Sphenophyllum.

Some account is also to be found in Renault ^ of the structural details of the leaves, but unfortunately he does not say from which of his specimensnbsp;they are taken. The weak vascular bundles consist only of a few tracheidesnbsp;combined into one strand, and surrounded by delicate bast-elements. Abovenbsp;and between these are hypodermal fibre-strands. Van Tieghem� indeednbsp;maintains that the bundles are diploxylous, like those of Cycadeae, butnbsp;Renault disputes this very decidedly. After seeing the preparations whichnbsp;he was kind enough to demonstrate to me, I must declare myself to benbsp;entirely of his opinion. Little is known of the attachment of the lateralnbsp;branches. No anatomical details are given of the only specimen figured bynbsp;Renault ^; it is a suspicious circumstance that there is no node to be seennbsp;at the point of departure of the branch, though it may indeed have beennbsp;rubbed off. Hence the possibility that this fragment may come from anbsp;triarch root is not to be ignored. Stur� too has his doubts. The root,nbsp;the structure of which appears in the transverse section supplied'by Renault has a diarch primary strand in the form of a transversal line andnbsp;surrounded by secondary wood, which, though perfectly uniform all round,nbsp;presents in other respects the structure of the stem of Sphenophyllum.nbsp;Hence we can hardly have any doubt about the true character of this object.

It remains only to examine the fructifications. These appear chiefly in the form of cylindrical spikes with close resemblance in habit to those ofnbsp;Calamariae, and have been repeatedly found as lateral ramifications of leafy

' Stur (10), p. 328. nbsp;nbsp;nbsp;^ Renault (2), vol. iv, Introd. p. i6, t. B. � van Tieghem (3), p. 1^3.

' Renault (16), t. 1, f. 3. nbsp;nbsp;nbsp;^ Stur (9), p. 16.nbsp;nbsp;nbsp;nbsp;� Renault )2), vol. iv, t. E, f. 2.

branchlets undoubtedly belonging to Sphenophyllum, as for instance near Wettin in tolerable abundance. Figures of such objects are to be found innbsp;Germar\ Geinitz^, Schenk�, and Schimper^, and diagrammatic representations in Grand� Eury�. Geinitz and Schimper agree in their accounts ofnbsp;the structure of these spikes, and a careful examination by Schenk � yieldsnbsp;the same results. Not having devoted any study to them myself, I willnbsp;adopt Schenk�s description of them in the following remarks. He says thatnbsp;the fructification is composed of moderately crowded uniform sporangiferousnbsp;whorls. The leaves of the whorls are hollowed out at the base, in somenbsp;cases forming a spur-like pocket, and then ascend so that their apicesnbsp;reach to the whorl next above, or are imbricated upon it. They resemblenbsp;the foliage-leaves of the vegetative branches in having the anterior marginnbsp;divided into several teeth. These fertile leaves are exactly superposed innbsp;the consecutive whorls in all Germar�s figures. If this is strictly correct, itnbsp;would agree well with the inner organisation of the plant as described to us.nbsp;On the other hand it would be hard to reconcile or be even irreconcileablenbsp;with that organisation, if it is really the case, as Schenk thinks, that fournbsp;leaves were usually united in one whorl. Renault � too protests against this.nbsp;Schenk states that the specimens hitherto examined were not adapted tonbsp;settle this point. It may therefore be supposed that with better materialnbsp;the number six characteristic of the group will be found also in the fructifications. The sporangia stand singly in the hollow of the base of the leaf,nbsp;which in Sphenophyllum angustifolium is almost spurred : they are lenticularnbsp;in shape and sessile, and vary in diameter from one to two and a halfnbsp;millimetres.

Diminutive spikes have been found by Witkowitz with Sphenophyllum tenerrimum in the beds at Ostrau, and as their leaves agree with the leavesnbsp;of that species in shape and in their dichotomous branching, they may belongnbsp;to it. They have been figured and described by Stur The sporangia lienbsp;closely crowded together between the leaf-whorls, filling the space betweennbsp;every two leaves; their insertion has not been exactly ascertained, thoughnbsp;Stur inclines to think that they were attached to the axis and not to thenbsp;base of the leaf.

Hitherto unfortunately no unquestionable inflorescence of Sphenophyllum has been found as a petrifaction. Renault� met with one fragment in the pebbles of Grand� Croix which may possibly belong to the group, but it is involved in too many doubts to be really taken into consideration. The bit of spike, which is only four millimetres in length, showsnbsp;superposed uniform leaf-whorls and a thin rudimentary central xylem-

Strand, and has therefore been refei'red to Sphenophyllum. Bodies like sporangia, but much out of shape, are attached partly in the axils of thenbsp;leaves, partly to the upper surface of the leaves. Those which originate innbsp;the leaves contain granulations of a whitish colour, and it is said thatnbsp;� these can only be microspores; � in and close to the axillary bodiesnbsp;are one or more larger bodies which are explained to be macrospores, butnbsp;which seem from the figure to be pluricellular and to have no very pronouncednbsp;character. Williamson again has described under the name Volkmannianbsp;Dawsoni a fossil, known only in one specimen, which from the structure ofnbsp;its axis may perhaps belong to Sphenophyllum, but which, so far as itsnbsp;imperfect preservation enables us to judge, differs essentially in its othernbsp;details from the recognised structure of that genus. Of the axis only thenbsp;outer rind and the central bundle-strand are preserved. The latter doesnbsp;in fact appear to consist entirely of tracheal elements, but they are badlynbsp;preserved. I satisfied myself of this from some preparations kindly lentnbsp;me by their owner. The transverse section is three-winged, but the wingsnbsp;are shorter and thicker than is usually the case in Sphenophyllae, andnbsp;have a broader tez'minal emai'gination. The sporangiferous leaves are notnbsp;bent geniculately upwards, and below they are united into a funnel-shapednbsp;continuous plate, from the inner surface of which there arise many stalk-likenbsp;processes. Several leaves are seen together obliquely cut through on thenbsp;transverse section, owing to the steepness with which the whorl ascends.nbsp;Then the space between them is filled with numerous sporangia, which arenbsp;arranged in a single row between the outer, in several rows between thenbsp;inner leaves; and between and close to the latter there are sections to benbsp;seen passing irregularly through the before-mentioned stalks, to whichnbsp;Williamson supposes the sporangia to have been attached. I cannot however find clear proof of this in the preparations. The sporangia containnbsp;many rather large globular uniform spores with a reticulately ornamentednbsp;exosporium, which appears on the section to be covered with small prickles.

Turning for the last time to the question, to which group of recent plants we shall consider Sphenophyllae to be most nearly related, I findnbsp;it veiy difficult to give a positive answer. Different authors have attemptednbsp;various arrangements, which have been discussed at length by Renault^.nbsp;It has gradually become the custom to bring them into the neighbourhoodnbsp;of Lycopodiaceae. Schenk^ especially and van Tieghem� have very recently and earnestly supported this view. Stur^ and Renault� are the onlynbsp;authors who have not assented to it. The former, relying on his theorynbsp;of the whorl-traces, would class them with Calamariae; and Renault�nbsp;unites them with Salviniae, and has defended this arrangement against

Schenk particularly and van Tieghem. I can find no grounds for this union with Salvinia, which is opposed to all that we know of thenbsp;fructifications. The heterospory which is employed to defend it isnbsp;more than doubtful^ and a comparison with the rudimentary central strandnbsp;of that aquatic plant would be a bold step, even if there was a resemblance between them ; but no such resemblance has been disclosed bynbsp;Janczewski�s careful examination of the bundle in Salvinia. On the othernbsp;hand, as it seems to me, the primary structure precludes all thoughtnbsp;of Calamariae and Equisetae. There therefore remains only the series ofnbsp;Lycopodeae, in which we may perhaps find some points of connection.nbsp;But here too much good-will is needed and various presuppositions.nbsp;Assuming for instance that the primary central bundle belongs to thenbsp;concentric type, then it may no doubt be compared with the axile strandnbsp;of Lycopodiae. But this is as yet only an assumption; the bundle mightnbsp;just as well be a triarch radial strand, and then there would be nonbsp;resemblance to the stmcture of the stalk in any living plant. Schenknbsp;endeavours to prove that the verticillate position of the leaves, which doesnbsp;indeed often occur in Lycopodium, is an unimportant difference, but he hasnbsp;overlooked the remarkable superposition of these whorls, which mustnbsp;however be an important element in the question and requires muchnbsp;consideration. To these peculiarities in Sphenophyllae must be addednbsp;the structure of the secondary wood, which has no analogue either innbsp;living or in any known fossil plants. It is not so much the appearancenbsp;of this formation, as its absolutely peculiar character, which must makenbsp;us hesitate, and all the more because, as has been already said, the comparison of the external characters and of the primary structure with thosenbsp;of Lycopodieae rests on very weak foundations. To compare the secondarynbsp;wood of Sphenophyllum with that of Sigillaria, as van Tieghem proposes,nbsp;is to my mind simply impossible. It will be best therefore to renouncenbsp;for the present all forced attempts at classification and to regard the groupnbsp;as sui generis, as standing by itself and independent. I myself inclinenbsp;to the view that it is only from the discovery of fresh specimens furthernbsp;back in the series of deposits that we can hope to find such a place fornbsp;Sphenophylleae in the system as will be fruitful of further results; but itnbsp;must be confessed that the prospect of such discoveries is at present unfortunately very small.

REMAINS OF STEMS OF DOUBTFUL AFFINITY, IN WHICH THE CHARACTER OF THE SURFACE IS UNKNOWN.

We have still to examine a certain number of fossil stems, the position of which is open to question because the character of their surface is quitenbsp;unknown. All stems of this kind, which could be connected with definitenbsp;groups of plants^ have been discussed in the preceding chapters; herenbsp;therefore we have to deal only with a few forms, for which no appropriatenbsp;place could be found before.

The first that may be mentioned is the genus Sigillariopsis, Ren.^, which might perhaps have been noticed in the chapter on Sigillariae. Itsnbsp;author has obtained several specimens from the pebbles of Autun. Thenbsp;one which he has figured^ consists of a fragment of stem in rather imperfect preservation, which is surrounded by the spirally arranged leavesnbsp;still in their natural position. The transverse section of the stem, smallnbsp;in diameter and with the rind and pith badly preserved, shows likenbsp;Sigillaria Menardi a narrow layer of secondary wood with scalariformnbsp;tracheides on the inside and pitted tracheides on the outside, after thenbsp;manner of Cycadeae. The longitudinal section� in the same work shouldnbsp;also be compared. Inside this ring of wood are numerous primary wood-strands, as in Sigillaria, lying close together, which, as we are expresslynbsp;told, are in a bad state of preservation, but which have their sfiiralnbsp;tracheides outside, as in that genus, and next to these on the insidenbsp;scalariform and pitted elements. We see that all this agrees perfectlynbsp;wfith what is known in the case of Sigillaria Menardi, with the singlenbsp;exception of the pitted tracheides which are not found in that species.nbsp;The leaves too are similar, narrow-lanceolate or linear, as may be concluded from their rhombic or somewhat irregularly triangular transversenbsp;sections ; but the rhombic sections show two vascular bundles close tonbsp;one another, while in the triangular section which is figured there isnbsp;only a median bundle. Renault considers that the latter is the transversenbsp;section of the tip of a leaf, and says^: � In the broadest part of the leafnbsp;are seen two vascular bundles, which are reduced to a single bundle

towards the point.� Other modes of explanation, for example the supposition of an alternation of leaves, seem to me to be preferable. The transversenbsp;section of the trace-bundle, according to the figure and the descriptionsnbsp;shows a structure essentially similar to that of Cordaites ; it is surrounded bynbsp;a stout parenchymatous sheath, and exhibits the initial group characterisednbsp;by spiral tracheides between the two wood-strands, the upper one ofnbsp;which forms an irregular group and is surrounded on one side by the lowernbsp;strand which is in the form of an arch. A hypodermal fibrous layer withnbsp;blunt projecting ribs is developed beneath the epidermis on both sidesnbsp;of the leaf. I have been obliged to depend entirely on Renault�s descriptionnbsp;for this interesting genus, which I have never examined myself; a fullernbsp;account of it from better preserved specimens would be very desirable.

The remains which Renault ^ has collected together provisionally under the name Poroxylon, and which differ from one another in not unimportant points, are also known to me only from the literature. There is anbsp;prospect of a full account of them by Bertrand and Renault, the main resultsnbsp;of which have already been published in a short preliminary communicationnbsp;by Bertrand�. According to Renault�s figures we must here distinguishnbsp;two separate types, one of which is represented by Poroxylon Boysseti andnbsp;P. Edwardsii, the other by P. Duchartrei. While the first two forms,nbsp;judging by the figure and the description, appear to have much resemblancenbsp;to Sigillariopsis, and show pith and rind and between them a ring of bundlesnbsp;surrounded by secondary wood, the figure of P. Duchartrei ^ has a centralnbsp;wood-strand of circular transverse section, in which groups of broad pittednbsp;tracheal elements are imbedded in a delicate parenchyma. This centralnbsp;strand is surrounded by a ring of secondary wood divided by very broadnbsp;medullary rays into a great number of wedges, which in their turn containnbsp;narrower, rays of parenchyma. The tracheides are pitted. Few scalariformnbsp;or s'piral cells were found on the borders of the central strand. Nothingnbsp;I'emains of the rind except a few fragments of secondary bast-wedges answering to the segments of the ring of wood.

It is possible that Bertrand�s and Renault�s � statements refer only to the type represented by the first-named species. At least I am unablenbsp;to reconcile the following words with the structure of Poroxylon Duchartrei:nbsp;� The centripetal ligneous masses (the primary bundles) do not converge towards the centre of the stem, even in slender stems.� This quite suits the firstnbsp;two species which resemble Sigillariopsis. In these there is a central pith,nbsp;and in it in P. Edwardsii there are dark points, which Renault takes fornbsp;gum-passages. Similar passages are found in P. Boysseti in the parenchymatous rind. On the inner border of each segment of the ring of wood

there is a primary bundle with an initial strand towards the outside. The bundle consists of pitted and scalariform tracheides. In the secondarynbsp;wood there are only pitted tracheides �, and these have the bordered pits,nbsp;which are crowded together as in Araucaroxylon and flattened into anbsp;polygonal shape, only on the radial surfaces. The secondary bast-regionnbsp;in Poroxylon Boysseti is homogeneous, in P. Edwardsii ^ it contains sieve-tubes with a broad lumen, which are said to resemble those of Encephalartos.nbsp;Outside it is the thick parenchymatous rind containing a large numbernbsp;of hypodermal fibre-strands with a radially elongated transverse section.nbsp;Bark is formed according to Bertrand and Renault in Poroxylon Edwardsii;nbsp;and in this process the first layer of periderm is developed on the innernbsp;border of the primary rind. The succeeding layers arise in the bast andnbsp;cut out flat scales of bark from beneath. The preliminary communicationnbsp;of the two authors already mentioned contains further important anatomico-morphological data, from which I select the following. The phyllotaxynbsp;isnbsp;nbsp;nbsp;nbsp;the leaf-trace is formed of a single strand. There are lateral

buds in the axils of the leaves, but they are not always developed. Unfortunately nothing is said about the leaves themselves. But Renault ^ has found fragments of leaf-stalks associated with the stems of Poroxylonnbsp;in the pebbles of Autun, which he inclines to refer to this group on accountnbsp;of their great resemblance to the stems. He says on this point in hisnbsp;Memoir �: � Their structure is so like that of the branches, that therenbsp;can be no doubt of their connection.� They show first of all on thenbsp;elliptical transverse section exactly the same short radial hypodermalnbsp;strengthening ribs mentioned above. In the middle of their stout thicknbsp;parenchyma, which is marked throughout with isolated dark points, liesnbsp;a much-expanded vascular bundle which is divided by medullary raysnbsp;into several segments lying beside one another. The bundle consistsnbsp;of an upper portion of wood, and an under portion of the same tonbsp;which the bast-layer is attached. The whole gives the impression thatnbsp;secondary growth must have taken place. The upper wood-portion,nbsp;which in that case would answer to the primary bundle of the stem, isnbsp;traversed by tracheides without regular arrangement, the scalariformnbsp;elements being beneath, the pitted above. In the lower portion thenbsp;pitted tracheides form straight parallel rows, as is usually the case innbsp;secondary wood. If all these statements are confirmed, there is notnbsp;much to be said against placing these two species of Poroxylon withnbsp;Cycadeae. Still they would differ from our recent forms in the importantnbsp;point, that the trace-bundles maintain the anomalous position of theirnbsp;initial strand on the outer side of the bundle even in the stem.

The next forms to be mentioned are the genera Lyginodendron, Will., and Heterangium, Corda, which seem to stand in a relation to one anothernbsp;similar to that of Poroxylon Boysseti to P. Duchartrei. Lyginodendronnbsp;Oldhamiamum, Will., a full account of which we owe to Williamson^, occursnbsp;frequently in the calcareous nodules of the coal-fields of Lancashire andnbsp;Yorkshire, and also in those of Langendreer and Orlau. A transversenbsp;section of a stem in a nodule from the latter locality is figured by Stur^.nbsp;These remains were first discovered by Binney, and were called Dadoxylonnbsp;Oldhamium. The name Lyginodendron adopted by Williamson was invented by Gourlie, who used it to express the peculiar impressions of rindsnbsp;with Dictyoxylon-structure mentioned above on pp. 8 and 218. As the namenbsp;is no longer necessary for this purpose, Williamson has transferred it to'ournbsp;plant, and not without reason, since some of these impressions do certainlynbsp;come from it, and it also shows Dictyoxylon-structure in the rind. A fullnbsp;account of the history of this genus will be found in Williamson.

At first sight the transverse section presents essentially the appearance of a stem of Cycadeae. We find a well-developed and rather thick ring ofnbsp;secondary wood divided by many broad medullary rays into numerousnbsp;plates a few cell-rows in breadth, quite after the manner of Cycadeae. Thenbsp;elements of this wood appear to be entirely pitted tracheides. Williamsonnbsp;states that zones have been observed which look like annual rings, but I donbsp;not find any in my specimens; they are said to occur particularly on oldnbsp;and very thick specimens, such as the one figured by Williamson�. Thenbsp;space inclosed by the ring of wood contains a central mass of parenchyma,nbsp;which in many cases however is entirely destroyed, and this is surrounded onnbsp;all sides by irregularly shaped bundles of varying length and breadth. Thesenbsp;bundles immediately adjoin the inner surface of the ring of wood; thenbsp;elements of smallest transverse section lie on their outer side. The bundlesnbsp;stand in no regular relation to the segments of the ring of wood. They arenbsp;usually more or less pushed out of their original position, owing to thenbsp;disappearance of the central parenchyma and the collapse of the stems;nbsp;but where these are preserved intact, as in one of Williamson�s figuresnbsp;there the bundles appear less as single separate bundles than as fragmentsnbsp;of a ring inclosing the central parenchyma, as in Sigillaria spinulosa (seenbsp;p. 352�3 Fig. 49). This would be in favour of the explanation thatnbsp;they are axile bundles with a parenchymatous centre, such as we foundnbsp;in Lepidodendrae. Further investigation will be required to determinenbsp;the truth of the one or the other view.

The rather thick rind separates into three layers. The innermost layer is the bast in the form of wedges, which are the direct continuation of the rays

of wood, and like them are separated from one another by broad medullary rays. The middle layer is the parenchymatous inner rind which is seldomnbsp;preserved ; its closed tissue contains many isolated darker cells. Lastly, thenbsp;outer rind is always well preserved; it consists of thick-walled elements,nbsp;and is traversed by hypodermal fibre-plates which appear on the transversenbsp;section as crowded radial stripes. The tangential section shows that thesenbsp;plates have a sinuous course, so that they meet in places and coalesce withnbsp;one another for short distances. In this way fusiform meshes filled with

parenchyma are formed between them ; we have in a word the well-known Dictyoxylon-structure (Fig. i).

Further investigation is required to make us fully acquainted with the structure of the bundles which pass from this ring of wood to the lateralnbsp;members. At present there is scarcely anything satisfactory to tell aboutnbsp;it. Bundles of different character are met with in the inner rind on everynbsp;transverse section, but it has not hitherto been possible to determine theirnbsp;course with certainty in the longitudinal direction. These bundles occur innbsp;three principal forms. The most frequent are bundles of somewhat irregularnbsp;roundish-ovate form on the transverse section, which lie side by side in

pairs and symmetrically with respect to one another ; this form is met with in three or four places in every preparation. The distance between thenbsp;bundles is of varying breadth ; sometimes they are in direct lateral contactnbsp;with one another (Fig. 49). This depends no doubt on the different heightsnbsp;at which the section has passed through them. It is difficult to determinenbsp;whether this bundle is concentric or collateral, because the bast-portion hasnbsp;been destroyed ; I am also still in doubt respecting the position of thenbsp;initial strand. It is to be hoped that the fine material which has beennbsp;recently obtained will soon settle this point. Its tracheal elements are likenbsp;those of the wood. I am inclined to think that these strands are leaf-traces,nbsp;though it is strange that they have never been met with in tangentialnbsp;sections in the Dictyoxylon-meshes of the outer rind. Their course mustnbsp;in any case be steeply ascending, since Williamson, on the strength of anbsp;longitudinal section which he has figured^, declares it to be vertical andnbsp;parallel to the ring of wood. I cannot however accept the view whichnbsp;he founds on this observation, namely that they are cauline bundles, fornbsp;reasons which will be mentioned presently. Next we have bundles ofnbsp;occasional but much less frequent occurrence, which are evidently composednbsp;of two separate parts. They always stand isolated and unusually close tonbsp;the outer edge of the wood, where there is always a broad open gap-likenbsp;primary ray corresponding to them from which they seem to emerge.nbsp;Each of these bundles consists of an outer normal secondary wood, whichnbsp;has its elements arranged in rows and is usually spread out like a fan, andnbsp;a primary strand forming its inner boundary and with its tracheides notnbsp;disposed in any order (Fig. 49 d). This strand is exactly like those whichnbsp;bound the pith, and the impression which it gives is as if one of thesenbsp;strands with the piece of secondary wood corresponding to it had comenbsp;out through the ring of wood. But as traces of a similar secondary growthnbsp;are found also in the transverse sections of the bundles of the first kind,nbsp;where they still lie near together, it is natural to regard all these transversenbsp;sections not only as collateral, but as actually belonging to one another.nbsp;If this is the true view,�a point which has yet to be determined,�then thenbsp;emerging strands, which are simple below and have experienced growth innbsp;thickness, would lose this growth further on, and ascending in the rindnbsp;would ultimately separate into two contiguous branches.

The bundles which have now been described are the only ones which I have myself observed in the material before me. But Williamson^ has innbsp;some cases met with a third kind, which he takes for the attachment-tracesnbsp;of lateral branches, because he was also able to observe their emergencenbsp;through the meshes of the Dictyoxylon-rind Their primary strand

appears to agree perfectly with that of the preceding kind, but it is surrounded by a secondary ring of normal wood divided by medullary rays.

Ti-ansverse sections of leaf-stalks ai'e very commonly found in company with the pieces of stem of Lyginodendron, and in such a position that thenbsp;unbiassed observer would at once think it probable that they belong to thenbsp;stems. They do in fact show exactly the same habit as the stems, the samenbsp;sub-epidermal plates of strengthening tissue, and a leaf-trace of twonbsp;symmetrical elliptical approximated bundles, which resemble minutely thenbsp;bundles of the first kind described above. Their transverse section is broad,nbsp;the upper side flat, the lower slightly convex; there are sharply projectingnbsp;edges on both sides. The resemblance to certain transverse sections ofnbsp;stalks of fern-leaves, for example to one figured by Williamson ^ andnbsp;referred to Rhachiopteris aspera, is evident. Moreover, countless fragmentsnbsp;of the laminae of this or of a very similar form are always to be found innbsp;the immediate neighbourhood of the nodules, and they have on them verynbsp;commonly small slightly projecting winged ribs, which appear in transversenbsp;section as odd, horn-shaped, entirely parenchymatous excrescences. Thesenbsp;ribs, strange to say, are found almost invariably in exactly the same formnbsp;on the leaf-stalks thus associated with Lyginodendron, in which they springnbsp;each of them from one of the meshes of parenchyma between the hypodermalnbsp;Dictyoxylon-plates. Williamson himself inclines to consider that these fern-leaves and leaf-stalks belong to the stems of Lyginodendron. He says^,nbsp;�I have pointed out the existence in the Lancashire nodules of abundance ofnbsp;small stems or petioles, to which I gave the provisional name of Edraxylon.nbsp;I have since succeeded in connecting these petioles with the leaflets ofnbsp;a Pecopteris. I think it far from impossible that these may prove to belongnbsp;to Dictyoxylon Oldhamium, but since I have not yet succeeded in correlatingnbsp;them with any certainty, I shall add no more respecting them at present.�nbsp;Strict proof can only be supplied by sections passing through the point ofnbsp;union of the two.

On the other hand, there is the resemblance to Cycadeae in respect of the structure of the stem, which has been already pointed out. Felix especially has drawn attention to these relations in a preliminary communication^.nbsp;But it is not so much recent Cycadeae which this writer would comparenbsp;with Lyginodendron, as the partial rings in the pith of Medullosa stellata.nbsp;Even if the Rhachiopteridae just mentioned really belong to Lyginodendron,nbsp;this would be no objection to Felix�s view, since, as was shown above, therenbsp;is no essential difference in the lamina of the leaf between Ferns andnbsp;Cycads; and Osmunda, Myelopteris and Sphenopteris refracta, G�pp. warnnbsp;us also to be careful in employing the leaf-bundle and its structure asnbsp;a ground of discrimination. But still there must have been important

Williamson (1), Vi, t. 52, f. 6. � Williamson (IJ, IV, p. 403.nbsp;Felix (2), p. 9;

differences in character between the central cylinder inclosed within the ring of wood, and the same cylinder as known in Cycadeae. All thesenbsp;things considered, I abstain from expressing an opinion one way or thenbsp;other with respect to the affinities of these remains. Renewed investigationnbsp;will no doubt throw more light upon them. Into speculations respectingnbsp;certain groups intermediate between Ferns and Cycads which might readilynbsp;be connected with the present subject, I do not propose to enter herenbsp;any more than in other places in this work, which would have been suitablenbsp;for them; the reader will find no difficulty in forming such an idea of themnbsp;as may be needful from the facts here given, and they will not fit into thenbsp;frame of such an account of our subject as was intended in the present work.

Corda ^ has described as Heterangium paradoxum a very imperfect bit of stem from the sphaerosiderites of Radnitz in Bohemia. It is nothing butnbsp;some shreds of tissue, in which irregular groups of broad and narrow pittednbsp;vessels are seen in the middle of a small-celled tissue which has been brokennbsp;up and disintegrated. Williamson subsequently recognised in these remainsnbsp;some fragments of the central strand of a stem which he had obtainednbsp;in section from the infra-Carboniferous calcai'eous nodules of Burntisland,nbsp;and which he accordingly named Heterangium Grievii^. I have receivednbsp;another and similar species through Cash�s kindness, which was obtained bynbsp;Mr. Binns at Halifax from the Lancashire nodules; it will probably benbsp;soon and fully described by Williamson. The identification with Corda�snbsp;specimen may be taken to be perfectly satisfactory; at all events I cannotnbsp;sympathise with the doubts expressed by Renault which are founded onnbsp;too strict an interpretation of Corda�s statements.

We shall have an idea of the structure of the stem in Heterangium Grievii, Will., if we imagine the central portion in a stem of Lyginodendronnbsp;to be occupied by a uniform closed primary vascular bundle, with its trachealnbsp;elements in irregular groups and irregularly imbedded in a fundamentalnbsp;parenchymatous tissue. The surrounding secondary wood is less stronglynbsp;developed than that of Lyginodendron, but is like it in all other respects.nbsp;All the tracheal elements have bordered pits. The thick parenchymatousnbsp;rind is traversed by leaf-traces which are here formed of one strand only;nbsp;these bundles Williamson in this case accepts as leaf-traces, though theynbsp;ascend almost as steeply as the analogous bundles in Lyginodendron. Thenbsp;outer hypodermal Dictyoxylon-layer is narrower than in Lyginodendron,nbsp;but its fibre-plates are more crowded together and of larger size. Thenbsp;inner layer is formed of compact parenchyrna, in which transverse lines ofnbsp;darker cells may be seen on the radial section following one another atnbsp;regular distances.

Corda (1), p. 22, t. 16. nbsp;nbsp;nbsp;� Williamson (1), iv, p. 394; tt. 28-31.nbsp;nbsp;nbsp;nbsp;'' Renault (1), p- 277-

even more doubtful than that of Lyginodendron. It cannot well be reckoned with Cycadeae on account of its central primary bundle; and onnbsp;the other hand, if there were no secondary growth, there would scarcely benbsp;any reason for doubting that it is of the nature of Ferns. The large andnbsp;few leaf-bundles are against its belonging to plants resembling Lycopo-diaceae, such as Williamson^ has suggested. But the near affinity tonbsp;Lyginodendron is obvious.

A quite peculiar and still little known genus is Kaloxylon^ Will., which was discovered by its author in the Lancashire calcareous nodules, and wasnbsp;subsequently obtained in some specimens from the Burntisland nodules,nbsp;which are from a much lower part of the series. It consists of axes of verynbsp;small diameter, and with their centre occupied by a uniform vascular strand.nbsp;This strand, the only one present in young specimens, shows a somewhatnbsp;polygonal outline, and is surrounded by a secondary growth formed ofnbsp;wedge-shaped portions not more than six in number, which are traversednbsp;by ordinary medullary rays of one row of cells, and are separated from onenbsp;another by broad gaps or rays. Each gap or ray is wedge-shaped bynbsp;increase of breadth towards the outside and is filled with parenchyma,nbsp;and, according to Williamson�s� description and figure, answers to a bay innbsp;the line of cambium. The rind outside of this cambium-zone is parenchymatous, and according to Felix ^ who examined sections of Kaloxylonnbsp;from the Langendreer nodules, is full of lacunae; two layers of somewhatnbsp;broader fibre-like elongated cells are developed on the extreme outside. Asnbsp;regards the character of the tracheal elements of the wood of Kaloxylon,nbsp;Williamson says that it belongs to the � reticulated type.� But this expression is very indefinite, for the English author refers to this type not onlynbsp;true reticulated vessels, but very often also bordered pit-elements, in whichnbsp;owing to imperfect preservation only the outer line of the border of thenbsp;pit is visible, as for example in Lyginodendron and Heterangium. In anbsp;rather oblique transverse section obtained by the author himself I thoughtnbsp;I saw scalariform vessels; but the specimen departs a little from the description in other respects, so that I do not quite trust to the determination.nbsp;Of the affinities of this fossil, which Williamson seeks in Lycopodinae,nbsp;nothing at all certain can in my opinion be for the present said.

Lastly must be mentioned here certain fossil remains from the Carboniferous formation, which probably represent roots of unascertained genera of Gymnosperms, and which have been described by Williamson � under thenbsp;name Amyelon radicans. Like many more sections of roots which cannotnbsp;at present be determined, they occur not unfrequently in the calcareousnbsp;nodules of Langendreer and England, and often reach a considerable thick-

� Williamson (l),iv, p. 405. nbsp;nbsp;nbsp;� Williamson (1), vii, p. 13:nbsp;nbsp;nbsp;nbsp;5-7-nbsp;nbsp;nbsp;nbsp;quot; Williamson (1),

Vll, t. 6, f, 32, and t. 7, f. 34. nbsp;nbsp;nbsp;* Felix (2).nbsp;nbsp;nbsp;nbsp;= Williamson (1), V, p. 67.

ness, due entirely to the compact massive secondary wood. Williamson ^ has both described and figured them. The copiously branched roots ^ shownbsp;in the centre a triarch primary wood-strand, and next to this and allnbsp;around it is the secondary wood which is frequently excentric. In oldernbsp;specimens concentric lines like rings of annual growth are plainly to benbsp;seen in the secondary wood�, and these should be carefully examined,nbsp;because a true formation of yearly rings has never been observed in anynbsp;other remains from the Carboniferous formation, and would therefore benbsp;particularly interesting. In other respects the wood shows little structuralnbsp;peculiarity. It consists of a uniform mass of pitted tracheal elements,nbsp;and is traversed by a great many secondary rays, which are formed of anbsp;single row of cells, and are often only one cell in depth. Two layers maynbsp;be distinguished in the thin rind. The inner layer consists of parenchymanbsp;with no regular disposition of its cells, but the outer layer shows on thenbsp;transverse section nothing but short fusiform rows of cells thrust in betweennbsp;one another, each row consisting of a large number of quite flat tabularnbsp;elements. It is obvious that each of these rows represents an originalnbsp;parenchymatous mother-cell, in which a number of tangential divisionsnbsp;were subsequently formed.

XVI.

PLANT-REMAINS OF DOUBTFUL AFFINITY, IN WHICH THE CHARACTER OF THE SURFACE ONLY IS KNOWN,nbsp;WHILE THE STRUCTURE IS UNKNOWN.

The name Vertebraria, Royle has been given to some obscure fossil remains known at present only from the Damuda beds of India which arenbsp;probably Triassic, and from the Newcastle beds of New South Wales. Inbsp;have had the opportunity of seeing many specimens of these remains in thenbsp;British Museum, and in the collection of Professor Boyd Dawkins at Manchester. The name comes from Royle who published good figures of hisnbsp;Vertebraria, but unfortunately without description of any kind. Somenbsp;account of these remains and a full report of the literature will be found innbsp;Bunbury ^ and O. Feistmantel

The Vertebrariae are cylindrical simple or more or less copiously branched forms with a circular transverse fracture. They fill the thicknbsp;beds of a brick-red or brownish-gray stone, often crossing the stratification.nbsp;The circular transverse section is divided by thin bands of coal, which meetnbsp;in the centre and spread ray-like to the circumference, into a few wedge-shaped masses, which increase in breadth towards the outside, and whennbsp;regularly disposed might at first sight suggest a comparison with thenbsp;surface-view of the leaf-whorl of Sphenophyllum. This comparison has innbsp;fact been made by M�Coy^, who finds the chief distinction betweennbsp;Sphenophyllum and Vertebraria in the crowding of the successive whorls,nbsp;which are so close together as to touch one another. If this were so, we shouldnbsp;see the spaces which answer to the surfaces of the leaves covered with anbsp;layer of coal, whereas they show in most cases only surfaces of fracture ofnbsp;the stone.

The cylinders are very frequently brought under our observation in radial and tangential longitudinal fractures, and then a strip of coal is seennbsp;running down the middle of the cylinder. The radiating bands of coal ofnbsp;the transverse section prove to be so many vertical plates, and appear of

is a similar but smaller stem, and is unbranched in the only known specie men, which is in the Museum at Strassburg. With such imperfect knowledgenbsp;of these remains, we can hardly expect to succeed in determining theirnbsp;affinities. Schimper wavered originally between Lycopodiaceae and variousnbsp;Monocotyledons. At length he says^: � We were on the point of declaringnbsp;in favour of the latter hypothesis (Lycopodiaceae), when minute examination disclosed in the spikes some seeds like small seeds of Coniferae,nbsp;a discovery scarcely calculated to advance us in our researches.� Butnbsp;he then refers them to Monocotyledons on account of these seeds,nbsp;about which I have been unable to satisfy myself from the originalnbsp;specimens. I quite agree myself with Schenk�s ^ opinion, that such anbsp;classification is altogether in the air, and that it can do no good andnbsp;may do harm, so long as we have no present proof of the existence of undoubted Monocotyledons or of any Angiosperms in these ancient deposits.nbsp;It may just be mentioned that another spike-like object, also found in thenbsp;Buntsandstein of Sulzbad, has been described by Brongniart � as Echino-stachys, and figured by Schimper

How little we know of the real nature of Spirangium � is shown at once by the variety of names which the remains in question have received in thenbsp;course of time from different authors. The first-known species was describednbsp;by Brongniart � as Palaeoxyris regularis. It comes from the Buntsandsteinnbsp;of Sulzbad in the Vosges, and has been figured by Schimper and Mougeot�^.nbsp;A second species is Palaeoxyris Miinsteri, Presl from the Rhaetic beds ofnbsp;Franconia, which has since been minutely examined by Schenk Othernbsp;remains of the same kind are stated by Saporta to have been found innbsp;the Rhaetic beds of Couches near Autun (Spirangium ventricosum andnbsp;in those of Palsj� in Schonen by Nathorst Spirangium Quenstedti, Schpr.nbsp;(Palaeoxyris^^) comes from the Keuper of Waldhausen near T�bingen. Anbsp;form which is common in the Wealden formation of Hanover has beennbsp;described by Ettingshausenas Palaeobromelia Jugleri, and Schenk^� hasnbsp;given fine figures of the same. The genus occurs also in the Carboniferousnbsp;formation, and has therefore an unusually extended vertical distribution.nbsp;It is true that the specimens of Palaeoxyris carbonaria from the Uppernbsp;Carboniferous deposits ofWettin are not above suspicion. These specimensnbsp;and the remains from the American Coal-measures described by Les-quereux as Spirangium Prendelii, Lesq. are declared by Schenk to be

course on the tangential section as vertical lines. Longitudinal sections of the kind were figured by Royle, and good descriptions of them are givennbsp;in the Palaeontologia Indica^. If the radial fracture passes through thenbsp;intervals between these plates, then there appears on each side of thenbsp;central strip of coal a series of fractures with rectangular bounding linesnbsp;passing through the stone ; and the transverse dividing planes in these fractures, which do not correspond on the two sides, also seem sometimes to contain traces of coal. More minute examination of the best specimens studiednbsp;by me would, I believe, bring to light some further remains of structure.

So far as it is possible to judge of the matter from mere outside view, it seems to me that Bunbury, whose opinion is shared by O. Feistmantel, isnbsp;quite right in supposing that the Vertebrariae were roots or stems with anbsp;central solid axis and a less compact cortical cylindei', and that prismaticnbsp;intercellular spaces in the latter were filled with the substance of the stone,nbsp;while the diaphragms were preserved in the form of bands of coal. Butnbsp;whether, as Feistmantel assumes, they really belong as roots to Phyllothecanbsp;and so to Schizoneura Gondwanensis, with which they are usually associatednbsp;in the beds, must remain at present undetermined. Specimens of greaternbsp;thickness are very rare ; a figure of such a cylinder is given in O. Feist-manteL. The form which Schmalhausen � describes as Vertebraria, fromnbsp;the Lower Oolite of Siberia, can scarcely belong to this group. The figurenbsp;gives the impression of pinnae of a fern-leaf rolled up after the manner ofnbsp;Scolecopteris, but the description of the remains does not well admit of thisnbsp;interpretation.

The remains named Aethophyllae, of which two species have been found in the quarry in the Buntsandstein at Sulzbad in the Vosges, are asnbsp;remarkable as they are little understood. No objects certainly belongingnbsp;to this group have, as far as I know, been found elsewhere. They appearnbsp;indeed sometimes in lists of Triassic plants from different localities, but innbsp;all these cases it is found that the determinations rest on quite unsatisfactory linear fragments of leaves. The two species, Aethophyllum stipu-lare, Brongn., and Ae. speciosum, Schpr, the former of which had beennbsp;previously described by Brongniart^ in i8a8, have been carefully examinednbsp;by Schimper �. Aethophyllum speciosum is an acropetally branched stemnbsp;more than two feet long, bearing linear leaves that lie scattered about onnbsp;the slab of stone, and having their main axis and lateral branches terminatednbsp;by long cylindrical spikes which form the fructifications. The spikes appearnbsp;to be composed of numerous small lanceolate acuminate scales, but thesenbsp;through imperfect preservation are very indistinct. Aethophyllum stipulare

absolutely nothing but badly preserved fragments of Lepidodendron. This decision appears to some extent forced and improbable, even in the case ofnbsp;the above remains, but it is shown to be without foundation by the manynbsp;fine specimens which have been found in the clay-ironstone workings innbsp;the Coal-measures of Coalbrookdale (Palaeoxyris helicteroides, Morris). Inbsp;have seen these remains in a hundred forms in the finest preservation innbsp;the British Museum, to which they had been recently removed through thenbsp;purchase of a large local collection.

These Spirangiae are peculiar fusiform bodies, in which we can distinguish an ovoid enlarged middle portion and two long extremities which narrow gradually in the form of a cone. They are usually found singly onnbsp;the planes of stratification ; but specimens of Spirangium Jugleri are notnbsp;uncommon in the Wealden, in which several of the fusiform bodies arenbsp;borne in an umbel on the top of a thin filiform stalk, on which there is nonbsp;appearance of nodes or appendages of any kind. The surface of the wholenbsp;body is marked with sharp ribs, usually six in number, which wind spirallynbsp;round it once or one and a half times, and then straighten themselves outnbsp;at the conical extremity. In consequence of the strong compression thenbsp;edges of the two sides are often seen simultaneously, and these cutting onenbsp;another necessarily produce rhombic areolae. This appearance is particularly striking in the specimen first described by Brongniart, and hence he 'nbsp;took the whole object for a flowering spike and the areolae for imbricatednbsp;bracts. He compared it with the spikes of the genus Xyris and chose itsnbsp;name accordingly. Ettingshausen perceived Brongniart�s error, and supposednbsp;that there were six valve-like twisted bract-scales surrounding a central body.nbsp;But I do not understand from this how he arrived at a comparison with thenbsp;inflorescences of Aechmea, Pourretia, and Bromelia. By Quenstedt Spirangium is compared with Cycadeae. Schenk ^ with a greater show of reasonnbsp;suggests for comparison the fructifications of Helicteres with their spirallynbsp;twisted carpels, but does not express any decided opinion. Schimper alsonbsp;simply places the plant with 'genera incertae sedis.� Nathorst has recentlynbsp;attempted to work out the comparison with Characeae; he sees in Spirangiae gigantic sporangia of Charae surrounded by spirally twisted envelope-tubes. The lateral boundaries of these tubes are supposed to correspond,nbsp;as in Chara, with the screw-lines. His work is written unfortunately in thenbsp;Swedish tongue, with which I, like most botanists, am unacquainted, so thatnbsp;I can only refer to reports upon it. Now that I have had the opportunitynbsp;of examining carefully the numerous specimens of Spirangium Jugleri in thenbsp;collection at Marburg, and also the large series from the Carboniferousnbsp;formation in the British Museum, I can only say with Schenk� thatnbsp;Nathorst�s view is the most attractive, but that it is impossible to obtain

the needful proofs in any direction until we can examine specimens in which the structure is preserved.

The Spirangiae do not represent a perfectly isolated type; that there may have been a whole group of similar forms in existence, may benbsp;concluded from the recent discovery of the genus Fayolia^ by Renaultnbsp;and Zeiller in the coal-mines of Commentry. Figures and a full descriptionnbsp;of this form may be expected in the great Flora of Commentry, uponnbsp;which these authors are engaged. The resemblance between Fayolia andnbsp;Spirangium is obvious, though in the former there are only two much morenbsp;strongly twisted screw-lines, which appear to answer to the margins of twonbsp;ribbon-like valves. On each of these is an appendage (� collerette') peculiarlynbsp;striated and entire or toothed, which is prolonged beneath the beak ofnbsp;the body into a free erect pointed and winged tooth. The plates themselves bear a I'ow of small circular scars, which approach the lower marginnbsp;and represent the points of attachment of subulate spines which arenbsp;occasionally preserved.

Some identical remains have been recently and almost simultaneously described by Weiss^ and Newberry�, which appear to be allied to Fayolianbsp;but are unfortunately in a much worse state of preservation. Gyrocalamusnbsp;palatinus, Weiss, was discovered in the Rothliegende (Lebach beds) nearnbsp;Cusel in the Rhenish Palatinate; Spiraxis major and S. Randallii ofnbsp;Newberry come from the Chemung beds of the Upper Devonian formation,nbsp;the former having been found in the State of New York, the latter innbsp;Pennsylvania. If these forms, as Weiss ^ assumes without any hesitation,nbsp;are really to be classed with Fayolia, it would not say much for the relationship of that genus to Characeae ; for both Gyrocalamus and Spiraxis,nbsp;owing to their greater length and more cylindrical form, have muchnbsp;less the appearance of fructifications. The unprejudiced observer wouldnbsp;take Weiss� fossil, which is broken off at both ends, simply for a fragmentnbsp;of the cylindrical cast of a stem. The surface unfortunately is verynbsp;imperfectly preserved, the American specimens showing only the stronglynbsp;projecting broad obtuse ribs running in very flat spirals; in the Germannbsp;specimen we see that each of the apparently simple ribs consists of twonbsp;parts, an inferior sharp keel, the proper rib, and a flatly convex stripnbsp;lying upon it, which belongs to the twisted band and bears a row of indistinct roundish scars exactly at the spot where the scars of the spinesnbsp;appear in the better preserved remains from Commentry.

We may now turn in conclusion to the genus Williamsonia, the last group of fossil remains w'hich we shall have to consider. The species ofnbsp;Williamsonia are very peculiar remains of fructifications, and their precisenbsp;structure is still very imperfectly known to us. That they are associated

by Williamson^ and Carruthers.^ with leaves and stems of Zamia gigas has been already stated on p. 91. O. Feistmantel� among more recent authorsnbsp;has adhered to this view, while Nathorst ^ and Saporta and Marion � rightlynbsp;consider that the grounds on which it rests are insufficient. These remainsnbsp;were first discovered in the Lower Oolites of Whitby. The greater partnbsp;of the specimens obtained from that locality have found their way alongnbsp;with the Yates collection into the Paris Museum, which may in consequence possess as many of them as all the English collections takennbsp;together. Various specimens were next found in the Upper Gondwanasnbsp;of India and at different levels in them ; in the Rajmahal, Cutch, andnbsp;Jabalpur beds (Jurassic). A full description of these remains will be foundnbsp;in O. Feistmantel. Another species, Williamsonia Forchhammeri, Nath,nbsp;comes from the Jurassic formation of Bornholm, and other forms havenbsp;recently been found in France, W. pictaviensis, Sap. et Mar., for example,nbsp;in the Oxfordian beds in the neighbourhood of Poitiers. According tonbsp;Saporta and Marion the type goes still further back ; these authors statenbsp;that they have remains of it, at present unpublished, from the infra-Liassicnbsp;beds of Hettange (Angulatae beds). They also refer to it a fossil, whichnbsp;resembles it but is still doubtful, from the Rhaetic beds of Bayreuth; thisnbsp;form will be found mentioned and figured in F. Braun � under the name ofnbsp;Weltrichia mirabilis, but Schenk strange to say, has left it unnoticed.nbsp;The determination has gained probability from the recent discovery of annbsp;apparently well-ascertained species, Williamsonia angustifolia � in thenbsp;Rhaetic beds of H�r in Schonen. The best-known species is thenbsp;large W. gigas, Carr, from Whitby. Specimens in the ordinary state ofnbsp;preservation show a wreath of numerous broadly lanceolate leaves, lyingnbsp;many deep on one another and curved or connivent into the shape of anbsp;bell or dome, and occurring as impressions with a thin rind of coal in thenbsp;brownish red sandstone of Whitby. The objects found are either mouldsnbsp;of the outer side of the bells, or more commonly the matter which fillednbsp;the bells in the form of rounded nodules bearing on their surface thenbsp;impressions of the leaves. In the latter case in the place where the axisnbsp;must have been and between the leaf-bases there is a hollow space, whichnbsp;under favourable circumstances is prolonged into the interior of the wreathnbsp;of leaves, and there answers to the space originally occupied by the organsnbsp;of fructification. A cast has been found in these specimens in a very fewnbsp;instances, corresponding in form to the casts which are artificially obtained.nbsp;This cast, figured by Williamson � from nature, has the form of a flasknbsp;with a protuberant body which passes gradually into a narrow neck with

� Williamson (10). nbsp;nbsp;nbsp;^ Carruthers (4).nbsp;nbsp;nbsp;nbsp;^ O. Feistmantel (1), II.nbsp;nbsp;nbsp;nbsp;* Nathorst (8).

^ Saporta et Marion (2), p. 234. nbsp;nbsp;nbsp;� F. Braun (1), t. 2.nbsp;nbsp;nbsp;nbsp;� Schenk (3).nbsp;nbsp;nbsp;nbsp;� Nathorst (8),

t. 8, ff. 8-ro. nbsp;nbsp;nbsp;� Williamson (10), t. 52, f. 4 and t. 53, ff. 6-8.

an expanded rim. Attached to it is a globular process with its upper extremity somewhat emarginate and even spread out into a small flatnbsp;surface. This flask-like body is ornamented externally with radiatingnbsp;striae or even with a polygonal mesh-work, which is regarded by authorsnbsp;as the remains of crowded anthers, attached to the extremity of the flaskshaped axis. O. Feistmantel ^ has figured a doubtful specimen which alsonbsp;perhaps represents the cast of a Williamsonia. The involucre of surrounding leaves is formed according to Saporta of several series, the leavesnbsp;in which increase successively in length. The stalk, which bears the wholenbsp;structure and which is covered with lanceolate leaves lying one on anothernbsp;like scales, has been preserved only in a very few cases. The leaves arenbsp;of a firm and solid character, and have a keel in the middle of the dorsalnbsp;side ; according to Saporta ^ they show an anastomosing nervation like thatnbsp;of Dicotyledons. I have myself been unable to discover anything of thenbsp;kind in the specimen in the Paris Museum, in which he observed it, and anbsp;French botanist who examined the piece with me for this purpose was notnbsp;more successful.

In the same beds are found peculiar circular disks with a funnel-shaped depression, and with the margin slit into long lanceolate lobes. Accordingnbsp;to Williamson ^ each of these lobes bears not far from its base an ovoidnbsp;projection formed of two parallel ridges, which Saporta however did notnbsp;find in the specimens to which he has had access. While Williamson seesnbsp;in these disks the remains of female flowers (he terms them �carpellarynbsp;disks�) and in the projections traces of the ovules, Saporta and Marionnbsp;think that they are only terminal expansions of the above-mentioned flaskshaped axis of the male flowers, and they consider that they have foundnbsp;the two in connection with one another. They say on this point : � Thisnbsp;expansion was the upper termination of the male apparatus and might benbsp;compared to the spongy cushion at the top of the spadix of Amorphophal-lus : one might even be tempted to see in it something analogous to thenbsp;circle of leaves above the inflorescence in Ananas. The organ in questionnbsp;is certainly the result of a transformation of the upper leaves of the branchnbsp;which has been changed into a spadix.� It is to be hoped that a publication yet to come from Saporta will contain further and more convincingnbsp;particulars on this subject.

There are moreover certain other objects which Saporta and Marion have considered to be female fructifications of our plant. For these theynbsp;refer especially to a specimen found by Nathorst� in Cloughton Bay on thenbsp;coast of Yorkshire, and named Williamsonia Leckenbyi. Close beside an

' O. Feistmantel nbsp;nbsp;nbsp;t. 3, f. 3.nbsp;nbsp;nbsp;nbsp;* Saporta et Marion (2), p. 237.nbsp;nbsp;nbsp;nbsp;� Williamson (10),

t. 52, f. I and t. 53, f. 2. nbsp;nbsp;nbsp;* Saporta et Marion (2), p. 240.nbsp;nbsp;nbsp;nbsp;* Nathorst (8), t. 8, f. 5.

involucre, the leaves of which are spread out by pressure into a stellate form, there lies on a surface of gray schist an irregular shred of tissue formednbsp;entirely of small cylinders placed palisade-fashion side by side, and showingnbsp;therefore crowded polygonal facets on its surface. This fragment in theirnbsp;opinion represents a portion of a rolled up spadix beset with peripheralnbsp;organs. They also figure^ a very fine and well-preserved fragment petrified innbsp;carbonate of iron and found by Mori�re in the Oxfordian strata of the Vachesnbsp;Noires in Normandy, which shows a spadix still in part surrounded by in-volucral leaves and with its surface actually presenting the same facetednbsp;appearance. The facets, which answer to small angularly pyramidal prominences, are arranged with regularity in a circle or rosette around a centralnbsp;deep-lying point. A layer of seeds lying beneath the surface is seen on thenbsp;longitudinal fracture, and the substance of the spadix underneath the seedsnbsp;is composed of stout parallel fibres. That this object is a fructification isnbsp;unquestionable on account of the seeds, and its resemblance to the spadix,nbsp;described above on p. 95, as belonging to the genus Bennettites, is obvious;nbsp;its connection with Williamsonia is only concluded from the presence of thenbsp;peripheral lanceolate involucral leaves, but we have seen that these occur innbsp;a similar manner in Bennettites. I have no doubt therefoi'e that this specimen belongs to Bennettites, but in saying this I have no intention of prejudging the question of its relation to Williamsonia; for it is still possiblenbsp;that further discoveries may show that the fructifications of Bennettites andnbsp;Williamsonia both belong to similar stems resembling the stems of Cycadeae,nbsp;and confirm the opinion of Williamson and Carruthers. But until the truthnbsp;of these conjectures is ascertained, we must be content to leave the relationship of Williamsonia undetermined. The improbability of F. Braun�s andnbsp;Nathorst�s ideas, who would place them, as they would Bennettites, withnbsp;Balanophoreae or Rafflesiaceae is patent, and needs no prolonged discussion.

LIST OF PUBLICATIONS.

Balfour, J. H. (1) Introduction to the study of Palaeontological Botany. Edinburgh, 1872.

Beneeke, E. W. (1) Ueher die Umgebungen von Esino in der Lombardei. Benecke, Geognostisch-palaontologische Beitrage, Bd. 2, Heft III.

Berendt. (1) Die im Bernstein befindlichen organischen Reste der Vorwelt. Bd. l, Abth. I. G�ppert und Berendt, Der Bernstein und die in ihm befindlichennbsp;Pflanzenreste der Vorwelt, 1845.

Berger, H. A. C. (1) Die Versteinerungen der Fische und Pflanzen im Sandstein der Coburger Gegend. Coburg, 1829.

Bergeron, J. (1) Note sur les strobiles du Walchia piniformis. Bulletin de la soc.

Bertrand, C. Eg. (1) Note sur le genre Vesquia, Taxin�e fossile du terrain Aachenien de Tournai. Bull, de la soc. bot. de France, vol. 30 (1883), p. 293.

(2) nbsp;nbsp;nbsp;Bertrand et B. Renault. Remarques sur les faisceaux foliaires des Cycad�es

actuelles et sur la signification morphologique des tissus des faisceaux unipolaires diploxyles. Comptes rendus de I�Acad., 24 Mai, 1886.

(3) nbsp;nbsp;nbsp;Bertrand et B. Renault. Caract�ristique de la tige des Poroxylons (Gymno-

spermes fossiles de I�epoque houill�re). Comptes rendus de TAcad., 17 Mai, 1886.

Beust, F. (1) Untersuchung fiber fossile Holzer aus Gr�nland. Inaug.-Diss. Z�rich, 1884.

Beysclilag, P. (1) Rhacopteris sarana, Beyschlag. Zeitschrift ffir die gesammten Natur-wissenschaften, herausgegeben von dem naturw. Verein ffir Sachsen und Thfiringen in Halle. Folge IV, vol. i (55) (1882), p. 411 seq.

Binney, E. W. (1) Observations on the structure of fossil plants found in the Carboniferous strata. Palaeontographical Society.

(2) nbsp;nbsp;nbsp;On some fossil plants showing structure from the lower Coal-measures of Lancashire.

(3) nbsp;nbsp;nbsp;A description of some fossil plants showing structure, found in the lower coal-seams

of Lancashire and Yorkshire. Philosophical Transactions, vol. 155 (1865), p. 579 seq.

(4) nbsp;nbsp;nbsp;Some observations on Stigmaria ficoides. Quarterly Journal of the Geological Soc.

(5) nbsp;nbsp;nbsp;E. quot;W, Binney and R. Harkness. An account of the fossil trees found at

St. Helens. London, Edinburgh and Dublin Philosoph. Mag. and Journ. of Sc., ser. 3, vol. 27 (1845), P- 241 seq.

(6) nbsp;nbsp;nbsp;Description of the Dukinfield Sigillaria. Quarterly Journal of the Geol. Soc. of

(7) nbsp;nbsp;nbsp;Remarks on Sigillaria and some spores found imbedded in the inside of its roots.

Bischoff. (1) Lycopodiolithes hexagonus, Bisch. Leonhard�s Zeitschrift fiir Mineralogie, Nette Folge, vol. i (1828), p. 253 seq.

Blanckenhorn, M. (1) Die fossile Flora des Buntsandsteins iind des Muschelkalks der Umgegend von Commern. Palaeontographica, vol. 32, Lief. 4 (1886).

Blum, B,. (1) Nachtrage zu den Pseudomorphosen des Mineralreiches. 1 (1847), II (1852), III (1863), IV (1879).

Bornemann, J. G. (1) Ueber organische Reste der Lettenkohlengruppe Thiiringens. Leipzig, 1856.

Boulay. (I) Le terrain houiller du Nord de la France et ses v�g�taux fossiles, 1876. Bowerbank. (1) A history of the fossil fruits and seeds of the London Clay. London,nbsp;1840.

Braun, A. (1) Ueber fossile Goniopterisarten. Zeitschr. der deutsch. geol. Ges., Bd. 4 (1852), p. 545.

(2) Ueber Marsilea Marioni, eine fossile Art aus der Tertiarzeit. Botan. Zeitg., 1872,nbsp;P- 653-

Braun, Fr. (1) Weltrichia, eine neue Gattung fossiler Rhizantheae. Flora, 1849, p. 705 seq.

(2) nbsp;nbsp;nbsp;^ V�g�taux fossiles' in Dictionnaire universel d�hist. nat. dirig� par M. Charles

(3) nbsp;nbsp;nbsp;Sur la classification et la distribution des v�g�taux fossiles en g�n�ral etc. M�moires

(4) nbsp;nbsp;nbsp;Prodrome d�une histoire des v�g�taux fossiles. Paris, 1828.

(5) nbsp;nbsp;nbsp;Sur les relations du genre Noggerathia avec les plantes vivantes. Coraptes rendus

(6) nbsp;nbsp;nbsp;Recherches sur les graines fossiles silicifi�es. Paris, 1881.

(7) nbsp;nbsp;nbsp;Observations sur la strucHcre int�rieure du Sigillaria elegans compar�e � celle des

L�pidodendro7i et des Stigtnaria et d, celle des v�g�taux vivants. Archives du Mus�uni d'hist. fiat., vol. i (1839),/. 406 seq.

(8) nbsp;nbsp;nbsp;Notice sur un fruit de Lycopodiac�es fossiles. Comptes rendus de I�Acad., vol. 67,

(9) nbsp;nbsp;nbsp;Essai d�une flore du gr�s bigarr�, Ann. des sc. nat., s�r. i, vol. 15 (1828), p. 435 seq.nbsp;Bronn. (1) Beitrage zur triasischen Flora und Fauna von Raibl. Leonhard und Bronn,

Brown, Eich. (1) On a group of erect fossil trees in the Sydney Coalfield of Cape Breton. Quarterly Journal of the Geol. Spc. of Lond., vol. 2 (1846), p. 393 seq.

(2) nbsp;nbsp;nbsp;Description of an upright Lepidodendron with Stigmaria roots in the roof of the

Sidney main coal in the island of Cape Breton. Quarterly Journ. of the Geol. Soc. of Lond., vol. 4 (1848).

(3) nbsp;nbsp;nbsp;Erect Sigillariae with conical taproots found in the roof of the Sydney main coal in

the island of Cape Breton. Quarterly Journ. of the Geol. Soc. of Lond., vol. 5 (1849), P- 354-

Brown, Eob. (1) Some account of an undescribed fossil fruit (Triplosporites). Transactions of the Linnean Society, vol. 20 (1851), p. 469 seq.

Buckland, W. (1) On the Cycadoideae, a family of fossil plants found in the Oolite quarries of the island of Portland. Transactions of the Geological Society of London, ser. 2, vol. 2 (1829), p. 395 seq.

(2) Buckland and de la B�che. On the Geology of the neighbourhood of Weymouthnbsp;and the adjacent parts of the coast of Dorset. Transactions of the Geol. Soc.nbsp;of Lond., ser. 2, vol. 4 (1835), p. l.

Bunbury. (1) On some fossil plants from the Jurassic strata of the Yorkshire coast. Quarterly Journ. of the Geol. Soc. of Lond., vol. 7 (1851), p. 179 seq.

(2) Notes on a collection of fossil plants from Nagpur, Central India. Quarterly Journ. of the Geol. Soc. of Lond., vol. 17 (1861), p. 325 seq., tt. 8-12.

Carpenter, W. B. (1) Introduction to the study of the Foraminifera. Ray Society. London, 1862.

Carruthers, W. (1) On Gymnospermatous fruits from the secondary rocks of Britain. Seemann�s Journ. of Botany, vol. 5 (1867), p. i seq.

(2) nbsp;nbsp;nbsp;On some undescribed Coniferous fruits from the secondary rocks of Britain. Geol.

(3) nbsp;nbsp;nbsp;On Beania, new genus of Cycadean fruit from the Yorkshire Oolites. Geol. Mag.,

(4) nbsp;nbsp;nbsp;On fossil Cycadean Stems from the secondary rocks of Britain. Transactions of

(5) nbsp;nbsp;nbsp;On the history, histological structure and affinities of Nematophycus Logani, Carr.

(Prototaxites Logani, Dawson) an Alga of devonian age. Monthly Microsc. Journ., vol. 8 (1872), p. 160 seq.

(7) nbsp;nbsp;nbsp;On the plant remains from the Brazilian Coal-beds with remarks on the genus

(8) nbsp;nbsp;nbsp;On the structure of a Fern stem from the lower Eocene of Herne Bay. Quarterly

(9) nbsp;nbsp;nbsp;On some Lycopodiaceous plants from the Old Red Sandstone of the North of Scot

(10) nbsp;nbsp;nbsp;Notes on fossil plants from Queensland, Australia. Quarterly Journ. of the Geol.

(11) nbsp;nbsp;nbsp;On the nature of the scars in the stems of Ulodendron, Bothrodendron and Mega-

phytum, with a synopsis of the species found in Britain. Monthly Microsc. Journ., vol. 3 (1870), p. 144 seq.

(12) nbsp;nbsp;nbsp;On Halonia of Lindley and Hutton, and Cyclocladia of Goldenberg. Geol. Mag.,

(13) nbsp;nbsp;nbsp;On the structure of the stems of the arborescent Lycopodiaceae of the Coal-

measures. Monthly Microsc. Journ., vol. 2 (1869), p. 177 seq., et p. 255 seq., tt. 27,31

(14) nbsp;nbsp;nbsp;On an undescribed cone from the Carboniferous beds of Airdrie, Lanarkshire.nbsp;Geol. Mag., vol. 2 (1865), p. 433 seq.

(15) nbsp;nbsp;nbsp;On the structure of the fruit of Calamites. Seemann�s Journ. of Botany, vol. 5

Caruel, T. (1) Observazioni sul genere di Cicadacee fossili Raumeria e descrizione di una specie nova. Bollettino del Reale Comitato geologico d�ltalia, n. 7-8 (1870),nbsp;p. 181 seq.

Castracane degli Antelminelli, E. (1) Die Diatomeen in der Kohlenperiode. Pringsh. Jahrb., vol. 10 (1876), p. I seq.

Clarke, J. M. (1) On Devonian spores. Americ. Journ. of Sc., vol. 29 (1885), p. 284 seq. Claypole, E. W. (1) On the occurrence of a fossil tree (Glyptodendron) in the Clintonnbsp;limestone (base of upper Silurian) of Ohio, U. S. Geol. Mag., London, new ser..nbsp;Decade II, vol. 5 (1878), p. 558 seq.

Coemans, Eug. (1) Description de la Flore fossile du premier �tage du terrain cr�tac� du Hainaut. M�m. de 1�Acad. roy. de la Belgique, vol. 36 (1867).

(2) Coemans, E. et J. J. Kickx. Monographie des Sphenophyllum d'Europe. Bulletin de 1�Acad. roy. de Belgique, se'r. 2, vol. 18 (1864), p. 134 seq.

(2) Ueber die versteinerten Holzer aus dem Norddeutschen Diluvium. Inaug.-Diss.nbsp;Breslau, 1876.

Cotta, C. B. (1) Die Dendrolithen in Beziehung auf ihren inneren Bau. Dresden, 1832. Cr�pin, P. (1) Description de quelques plantes fossiles de l��tage des Psammites dunbsp;Condroz (D�vonien sup�rieur). Bulletin de 1�Acad. royale Belg., 2 s�r., vol. 38 (1874).nbsp;Dana, J. D. (1) United States exploring Expedition under command of Charles Wilkes,nbsp;U. S. N., Geology, without date.

Dauhr�e. (1) Min�ralisation subie par des d�bris organiques, v�g�taux et animaux dans I�eau thermale de Bourbonne-les-Bains. Comptes rendus de 1�Acad. des Sc. denbsp;Paris, vol. 81 (1875), p. 1008.

Dawes, J. S. (1) Remarks upon the internal structure of Halonia. Quarterly Journ.

Dawson, J. quot;W. nbsp;nbsp;nbsp;(1) Geological Survey of Canada; Alfred R. Selwyn, F.G.S., Director.

� The fossil flants of the devonian and upper silurian for7nations of Canada. Vol. I (1871), vol. 2 (1882).

(2) nbsp;nbsp;nbsp;Acadian Geology, an account of the geological structure and mineral resources of

(3) nbsp;nbsp;nbsp;Notes on Prototaxites and Pachytheca discovered by Dr. Hicks in the Denbig-

shire grits of Corwen. Quarterly Journ. of the Geol. Soc. of Bond., vol. 38 (1882), p. 103.

(4) nbsp;nbsp;nbsp;Notes on new Erian Plants. Quarterly Journ. of the Geol. Soc. of Bond., vol.

(5) nbsp;nbsp;nbsp;On fossil plants from the devonian rocks of Canada. Quarterly Journ. of the Geol.

(6) nbsp;nbsp;nbsp;On the Flora of the devonian period in North Eastern America. Quarterly Journ.

(7) nbsp;nbsp;nbsp;Geological Survey of Canada ; Alfred R. Selwyn, F.G.S., Director�Report on the

fossil plants of the lower Carboniferous and Millstone grit formations of Canada. Montreal, 1873.

(8) nbsp;nbsp;nbsp;On the conditions of the deposition of coal, more especially as illustrated by the coal

formation of Nova Scotia and New Brunswick. Quarterly Journ. of the Geol. Soc. of Bond., vol. 22 (i866), p. 95 seq.

(9) nbsp;nbsp;nbsp;On the structure and affinities of Sigillaria, Calamites and Calamodendron.

(11) nbsp;nbsp;nbsp;Further observations on the devonian plants of Maine, Gaspe and New York.

(12) nbsp;nbsp;nbsp;On the lower Coal-measures as developed in British America. Quarterly Journ. of

(13) nbsp;nbsp;nbsp;Geological Survey of Canada. Report on the fossil plants of the lower Carboniferous

(14) nbsp;nbsp;nbsp;Notice of the occurrence of upright Calamites near Pictou, Nova Scotia. Quarterly

Debey und v. Ettingshausen. (1) Die urweltl. Acrobryen des Kreidegebirgs von Aachen und Maestricht. Denkschr. d. k. k. Acad. d. Wissensch. zu Wien, vol. 17 (1859),nbsp;p. 183 seq.

Deecke, W. (1) Ueber einige neue Siphoneen. Neues Jahrb. f. Min., Geol. und Pal. Jahrgang 1883, Bd. l, p. l seq.

Delesse. (1) �tudes sur Ie m�tamorphisme. Ann. des mines, s�r. 5, vol. i2 (1857), pp. 127-708.

Delgado, J. P. N. (1) Etude sur les Bilobites et autres fossiles des quartzites de la base du syst�me silurique du Portugal. Section des travaux g�ologiques du Portugal.nbsp;Lisbonne, 1886.

Dyer, W. T. Thiselton. (1) On some coniferous remains from the lithographic stone of Solenhofen. Geol. Mag., vol. 9, No. 5 (May, 1872).

Ehrenherg. (1) Ueber das Massenverhaltniss der jetzt lebenden Kieselinfusorien und iiber ein neues Infusorienconglomerat als Polirschiefer von Jastraba in Ungam.nbsp;Abh. d. Berliner Akademie, 1836, p. 109 seq.

(2) Ueber noch jetzt zahlreich lebende Thierarten der Kreidebildung und den Orga-nismus der Polythalamien. Abh. der Berliner Akademie, 1839, p. 81 seq.nbsp;von Eichwald. (1) Lethaea rossica. Stuttgart, 1853-1868.

Emmons, Etaenezer. (1) Geological Report of the Midland Counties of North Carolina. New York and Raleigh, 1856.

Essner, B. (1) Ueber den diagnostischen Werth der Anzahl und H�he der Mark-strahlen bei den Coniferen. Abhandlungen der naturforschenden Gesellschaft zu Halle, Bd. 16 (1882).

von Ettingshausen, C. (1) Die Tertiarfioren der Oesterreichischen Monarchie. Abh. der k. k. geol. Reichsanst. zu Wien, Bd. 2 (1855).

(2) nbsp;nbsp;nbsp;Zur Lias- und Oolithflora. Abhandl. der k. k. geol. Reichsanstalt zu Wien, vol. l,

(3) nbsp;nbsp;nbsp;Die Steinkohlenflora von Stradonitz. Ahhandl. der k. k. geol. Reichsanstalt zu

(4) nbsp;nbsp;nbsp;Die fossile Flora des Tertiarbeckens von Bilin. Denkschr. der k. k. Akademie zu

(5) nbsp;nbsp;nbsp;Die Steinkohlenflora von Radnitz in Bohmen. Abhandl. der k. k. Reichsanst. zu

(6) nbsp;nbsp;nbsp;Ueber Palaeobromelia, ein neues fossiles Pflanzengeschlecht. Abhandl. der k. k.

(7) nbsp;nbsp;nbsp;Die fossile Flora des mahrisch-schlesischen Dachschiefers. Denkschriften der

(8) nbsp;nbsp;nbsp;Beitrag zur naheren Kenntniss der Calamiten. Sitzungsber. der k. k. Akademie zu

Eeistmantel, Karl. (1) Ueber die Noggerathien und deren Verbreitung in der b�h-mischen Steinkohlenformation. Sitzungsber. der k. b�hm. Ges. d. Wissenschaften in Prag, Jahrgang 1879, p. 75 seq.

Eeistmantel, Ottokar. (1) Palaeontologische Beitrdge. Palaeontographica, Suppletnent 3, Lief. 3, Heft 1-4.

I. Ueber die indischen Cycadeengattungen Ptilophyllum und Dictyozaniites.nbsp;Heft I, 1877.

III. Paldozoische und mesozoische Flora d. �stl. Australiens. Heft 2, 3, 4,nbsp;1878-1879.

(2) nbsp;nbsp;nbsp;Bemerkungen iiber die Gattung Noggerathia, Sternbg., sowie die neuen Gattungen

N�ggerathiopsis, Feistm. und Rhiptozamites, Schmalh.; Sitzungsber. d. k. bohm. Ges. d. Wissenschaften in Prag, Jahrgang 1879, p. 444 seq.

(3) nbsp;nbsp;nbsp;Die Versteitierungen der bohmischen KoMenablagerungen. Palaeontographica, Bd.

(4) nbsp;nbsp;nbsp;Ueber Baumfarrenreste der bohmischen Steinkohlen-, Perm- und Kreideformation.

Abhandl. der kgl. b�hm. Gesellsch. d. Wissenschaften, 6. Folge, Bd. 6 (1873), Prag, 1874.

(5) nbsp;nbsp;nbsp;Das Kohlenkalkvorkommen bei Rothwaltersdorf in der Grafschaft Glatz und dessen

organische Einschl�sse. Zeitschr. der deutschen geolog. Gesellschaft, vol. 25 (1878), p. 463 seq.

(2) Strukturzeigende Pflanzenreste aus der oberen Steinkohlenformation Westphalens.nbsp;Berichte der Naturf. Gesellschaft zu Leipzig. Jahrg. 1885, p. 7 seq.

Fischer, H. (1) H. Fischer und D. Eiist. Ueber das mikroskopische und optische Verhaken verschiedener Kohlenwasserstoffe, Harze und Kohlen. Groth�s Zeit-schrift f Krystallographie, vol. 7 (1882), p. 209 seq.

Fontaine and White. (1) Second geological survey of Pennsylvania PP. The permian or upper carboniferous Flora of West Virginia and Pennsylvania. Harrisburg,nbsp;1880.

Gardner, J. Starkie. (1) A monograph of the British eocene Flora. Palaeontograph.

Soc., vol. 33 (1879), vol. 34 (1880), vol. 36 (1882), vol. 37 (1883), vol. 38 (1884). Geinitz, H. B. (1) Dyas, 1861.

(2) nbsp;nbsp;nbsp;Nachtrage zur Dyas. I. Mitth. aus dem mmer. geolog. paliiont. Museum in

(3) nbsp;nbsp;nbsp;Ueber zwei neue dyadische Pflanzen. Jahrb. f Mineralogie, etc., 1863, p. 525.

(4) nbsp;nbsp;nbsp;Geinitz und von Gutbier. Die Versteinerungen des Zechsteingebirges und

(5) nbsp;nbsp;nbsp;Die Versteinerungen der Steinkohlenformation in Sachsen, 1855.

(6) nbsp;nbsp;nbsp;Ueber rhatische Pflanzen- und Thierreste in den argentinischen Provinzen La

Rioja, San Juan und Mendoza. Palaeontographica, Supplem. Ill, Lief 2, Cassel, 1876.

(7) nbsp;nbsp;nbsp;Ueber einige seltene Versteinerungen aus der unteren Dyas und der Steinkohlen

(8) nbsp;nbsp;nbsp;Darstellung der Flora des Hainichen-Ebersdorfer und des Fl'�haer Kohlenbassins.

Germar, E. F. (1) Die Versteinerungen des Steinkohlengebirges von Wettin tind Ldbejiin im Saalkreis. Halle, 1844-1849.

Gilkinet, A. (1) Sur quelques plantes fossiles de Tetage des Psammites du Condroz.

Goldenberg, Fr. (1) Flora Saraepontana fossilis. Die Pflanzenversteinerungen des Steinkohlengebirgs von Saarbriicken. Saarbriicken, 1855-1862.

(2) Ueber den Charakter der alten Flora der Steinkohlenformation im allgemeinen und die verwandtschaftliche Beziehung der Gattung Noeggerathia insbesondere.nbsp;Verhandlungen des naturhistor. Vereins der pr. Rheinlande, vol. 5 (1848), p. 17 seq.nbsp;G�ppert. (1) Die Gattungen derfossilen Pflanzen, 1841.

(fi) Die fossile Flora der permischen Formation. Palaeontographica, vol. 12, Cassel, 1864-1865.

(4) nbsp;nbsp;nbsp;Monographic der fossilen Coniferen. Natuurk. Verhandelingen van de Hollandsche

(6) nbsp;nbsp;nbsp;Revision meiner Arbeiten iiber die Stamme der fossilen Coniferen, insbesondere der

Araucariten und iiber die Descendenzlehre. Botanisches Centralblatt, vol. 5 (1881), p. 378 seq., vol. 6 (1881), p. 27 seq.

(7) nbsp;nbsp;nbsp;Beitrage zur Kenntniss fossiler Cycadeen. N. Jahrb. f Mineralogie, Geol. u. Pal.,

(8) nbsp;nbsp;nbsp;Ueber die fossilen Cycadeen �berhaupt, mit R�cksicht auf die in Schlesien verkom-

menden Arten. Uebersicht der Arbeiten und Veranderungen der schlesischen Gesellsch. f vaterlandische Cultur, 1843. Breslau, 1844, p. 114 seq.

(9) nbsp;nbsp;nbsp;Ueber die gegenwartigen Verhaltnisse der Palaontologie in Schlesien, sowie uber

fossile Cycadeen. Denkschr. der schles. Gesellsch. f. vaterland. Cultur (1853), p. 259 seq.

INDEX OF LITERATURE.

(11) nbsp;nbsp;nbsp;Goppert und Stenzel. Die Medulloseae. Eine netie Grufpe der fossilen Cycadeen.

(12) nbsp;nbsp;nbsp;Fossile Flora des Uebergangsgebirges. Nova Acta Loop. Carol., vol. 22, Stipplem.

(13) nbsp;nbsp;nbsp;Ueber die Kohlen von Mal�wka in Central-Russland, Gouvernement Tula,

Sitzungsber. der M�nchener Akad. d. Wissensch. Natw.-math. Cl., vol. l (1861), p. 199 seq.

(14) nbsp;nbsp;nbsp;Abhandlicng ah Antwort aiij die Preisfrage iiber die Entstehung der Steinkohlen.

Natuurk. Verhandl. v. de Holla7idsche Maatschappy de Wetensch. te Harle7ii, ser. 2, vol. 4 (1848).

(15) nbsp;nbsp;nbsp;Ueber die Bildung der Versteinerungen. Annalen der Physik und Chemie, Bd. 38

116) Skizzen zur Kenntniss der Urwalder Schlesiens und Bohmens. Nov. Act. Nat. Cur., Bd. 34 (1868).

(17) nbsp;nbsp;nbsp;Ueber den versteinten Wald von Radowenz bei Adersbach in B�hmen und iiber den

Versteinerungsprozess �berhaupt. Jahrb. d. k. k. geol. Reichsanstalt zu Wien, vol. 8 (1857), p. 725 seq.

(18) nbsp;nbsp;nbsp;Die tertiare Flora von Schossnitz in Schlesien. G�rlitz, 1855.

(19) nbsp;nbsp;nbsp;Ueber die fossile Flora der silurischen, der devonischen und unteren Kohlenforma-

tion Oder des sog. Uebergangsgebirges. Nova Acta Leopoldino-Carolina, Bd. 27 (Jena, i860), p, 425 seq.

(20) nbsp;nbsp;nbsp;Ueber die Stig77iaria ficoides. Zeitschrift der deiitschen geolog. Geselhchaft, vol. 3nbsp;(1851),/. 278 seq.

(21) nbsp;nbsp;nbsp;Goppert und. A. Menge. Die Flora des Bernsteins U7id ihre Bezieh7i7ige7i siir

Flora der Teriidrfor77iation U7id der Gegenwart, vol. i (1883), vol. 2 {bearb. v. Conwentz, 1886).

(22) nbsp;nbsp;nbsp;Ueber Aphyllostachys, eine neue fossile Pflanzengattimg aus der Gruppe der

Calamarien, sowie uber das Verhaltniss der fossilen Flora zu Darwin�s Trans-mutationstheorie. Nova Acta Leop. Carol., vol. 32 (1865).

Grand� Eury, Cyrille. (1) Flore Carbonifire du d�pt. de la Loire et die ce7itre de la Fra7tce, 1877.

(2) Me77ioire ster la for7nation de la hoieillc. A7inales des 77iines, sir. 8, t. 2 (1882), p. 99 seq. Revisio7i of the above by G. de Saporta in Revue des deux 77iondes,nbsp;t. 54 (1882),/. 657 seq.

Grey, George. (1) Remarks on some specimens from South Africa. Quarterly Journ of the Geol. Soc. of Bond., vol. 27 (1871), p. 49.

Grisebach, A. (1) Ueber die Bildung des Torfs m de7t E77is7nooren aus dere7i ienvera7t-derter PJlanzendecke. Gottingen, 1846. {Aus Gottinger Studi�n, Jahrgang Giimbel, C. W. (1) Die sogenannten Nulliporen, etc. Abh. der M�nchener Akad.,nbsp;math.-phys. Cl., Bd. ii (1S74).

1. nbsp;nbsp;nbsp;Theil. Die Nulliporen des Pflanzenreichs, Lithothamnium, p. 13.

2. nbsp;nbsp;nbsp;Theil. Die Nulliporen des Thierreichs, Dactyloporideae, p. 231.

(2) Beitrage zur Kenntniss der Texturverhiiltnisse der Mineralkohlen. Sitzber. d. M�nch. Akad., math.-phys. Cl., vol. 13 (1883), p. in seq.

Hall, J. (1) Natural History of New York, Part VI, Palaeontology, vol. l (1848), vol. 2 (1851).

(2) Descriptions of the fossil reticulate Sponges constituting the family Dictyospongidae. Thirty-fifth Annual Report of the New York State Museum of Nat. History (1884),nbsp;p. 465 seq.

Haughton, S. (1) On Cyclostigma, a new genus of fossil plants from the old red sandstone of Kiltorkan, Co. Kilkenny. Journal of the Royal Dublin Society, vol. 2 (1859), p. I seq. See also Annals and Mag. of Nat. Hist., ser. 3, vol. 5 (i860), p. 443 seq.

Hausmann, J. Fr. L. (1) Oryktographie des Harzes, in Holtzmann, Hercynisches Archiv. One volume, Halle, 1805.

(2) Ueber das Vorkommen verschiedener Kieselgebilde in Begleitung des Basaltes.nbsp;Studi�n des G�ttingischen Vereins bergmannischer Kreunde, vol. 7, p. 139 seq.nbsp;Heer, O. (1) Zur Geschichte der Ginkgoartigen Baume. Bot. Jahrb�cher f�r Syste-matik, Pflanzengeschichte und Pflanzengeographie, herausgeg. von Engler, vol. Inbsp;(1881), p. I seq.

(2) nbsp;nbsp;nbsp;Beschreibung der Pflanzen und Insekten in A. Escher von der Linth, Geologische

Bemerkungen �ber das n�rdliche Vorarlberg, etc. Neue Denkschriften der allgem. schweizerischen Ges. f. d. ges. Naturw., Bd. 13 (1853), p. 117 seq., t. 6.

(4) nbsp;nbsp;nbsp;Ueber das geologische Alter der Coniferen. Botan. Centralblatt, Bd. 9 (1882),

(7) nbsp;nbsp;nbsp;Beitrage zur Kreideflora. I. Fl. v. Moletein in Mahren. Neue Denkschr. d.

(8) nbsp;nbsp;nbsp;Zur Geschichte der Ginkgoartigen Baume in Engler�s Botanischen Jahrb�chern, Bd.

(9) nbsp;nbsp;nbsp;The lignites and clays of Bovey Tracey, Devonshire. Philosophical Transactions,

(12) nbsp;nbsp;nbsp;Miocane baltische Flora. Beitrage zur Naturkunde Preussens, herausgegeben v. d.nbsp;k. physikalisch-�konomischen Gesellschaft zu K�nigsberg, vol. 2 (1869).

(13) nbsp;nbsp;nbsp;Ueber permische Pflanzen von Fiinfkirchen in Ungarn. Mittheilungen aus demnbsp;Jahrbuch der k. ungarischen geol. Anstalt, vol. 5 (1878), p. I seq.

(14) nbsp;nbsp;nbsp;Contributions k la flore fossile du Portugal. Ziirich, 1881.

(15) nbsp;nbsp;nbsp;Beitrage zur Kreideflora. II. Zur Kreideflora von Quedlinburg. Neue Denk

schriften d. allgem. schweizer. Gesellsch. f. d. ges. Naturw., Bd. 24 (Ziirich, 1871),

(16) nbsp;nbsp;nbsp;Les charbons feuillet�s de D�rnten et d�Utznach. Discours de M. Ie Professeur O.

Heer, traduit par M. Charles-Th. Gaudin. Archives des sciences de la Biblio-th�que universelle de Gen�ve, vol. 2 (1858), p. 305 seq.

Heyer, F. (1) Beitrage zur Kenntniss der Fame des Carbon und des Rothliegenden im Saar-Rheingebiet. Botanisches Centralblatt, Bd. 19 (1884), p. 248 seq.

Hick, Th. and Cash, Wm. (1) Contributions to the fossil Flora of Halifax, pt. IV. Proceedings of the Yorkshire Geological and Polytechnic Society, New ser., vol. 8nbsp;(1883), p. 85 seq.

(2) Myriophylloides Williamsoni, Hick and Cash. Proceedings of the Yorkshire Geological and Polytechnic Society, vol. 7 (1881), part IV, p. 400 seq.

Hicks, H. (1) On the discovery of some remains of plants at the base of the Denbig-shire grits near Corwen, North Wales. Quarterly Journ. of the Geol. Soc. of Bond., vol. 37 (1881), p. 482, t. 25.

(2) Additional notes on the land plants from the Pen y Glog slate-quarry near Corwen, North Wales. Quarterly Journ. of the Geol. Soc. of Bond., vol. 38 (1882),nbsp;p. 97 seq.

Hirsehwald. (1) Ueber Umwandlung von verstiirzter Holzzimmerung in Braunkohle im alten Mann der Grube Dorothea bei Clausthal. Zeitschr. d. deutschen geol.nbsp;Ges., Bd. 25 (1873), p. 364-

Hooker, J. D. (1) J. D. Hooker and E. W. Binney. On the structure of certain limestone nodules enclosed in seams of bituminous Coal, with a description of somenbsp;Trigonocarpons contained in them. Philosophical Transactions, vol. 145 (l855)gt;nbsp;p. 149 seq.

(2) nbsp;nbsp;nbsp;On the sphaeroidal bodies resembling seeds from the Ludlow bonebed. Quarterly

(3) nbsp;nbsp;nbsp;Remarks on the structure and affinities of some Lepidostrobi. Memoirs of the

(4) nbsp;nbsp;nbsp;On some peculiarities in the structure of Stigmaria. Memoirs of the Geological

(5) nbsp;nbsp;nbsp;On a new species of Volkmannia. Quarterly Journ. of the Geol. Soc. of Lond., vol.

Kidston, E. (1) On the fructification of Zeilleria delicatula, Sternbg., with remarks on Urnatopteris tenella, Brongn. and Hymenophyllites quadridactylites, Gutb. Quarterly Journ. of the Geol. Soc. of Lond., vol. 40 (1884), p. 590 seq., t. 25.

(2) nbsp;nbsp;nbsp;On the relationship of Ulodendron to Lepidodendron, Bothrodendron, Sigillaria

and Rhytidodendron. Annals and Magazine of Natural History, ser. 5, vol. 16 (1885), p. 123 seq.

(3) nbsp;nbsp;nbsp;On a new species of Psilotites from the Lanarkshire Coalfield. Annals and Maga

(4) nbsp;nbsp;nbsp;On the affinities of the genus Pothocites, Paterson ; with the description of a

specimen from Glencartholm, Eskdale. Annals and Magazine of Natural History, ser. 5, vol. II (1883), p. 297 seq.

(5) nbsp;nbsp;nbsp;On a new species of Lycopodites, Gold, from the calciferous Sandstone series of

Scotland. Annals and Magazine of Natural History, ser. 5, vol. 14 (1884), p. ill seq.

Kleeberg, A. (1) Die Markstrahlen der Coniferen. Botan. Zeitung (1885), p. 673 seq. Knop. (1) Beitrage zur Kenntniss der Steinkohlenformation in dem Rothliegenden imnbsp;Erzgebirge. N. Jahrb. f. Min. v. Leonhard u. Bronn (1859), pp. 532-601, 671-720.nbsp;Kraus, G. (1) Mikroskopische Uniersuchungen iiberden Bau lebender und vorweltUchernbsp;Nadelh'�lzer. Wiirzburger Naturwissenschaftl. Zeitschrift.,vol. 5 (1864),/. 144^^7.

(2) nbsp;nbsp;nbsp;Emige Benierkungen iiber die verkieselten Stdmme des frdnkischen Keupers tmd

zur Kenntniss der Araucarien des Rothliegenden und der Steinkohlenformation. Wiirzburger Naturw. Zeitschr., vol. 6 (1866), �. 64 seq.

(3) nbsp;nbsp;nbsp;Beitrage zur Kenntniss fossiler Holzer. Abhandlungen der Naturforschenden

Kuntze, O. (1) Ueber Gey sirs und nebe?ianstehende verkieselte Bdume. Das Ausland, 1880.

Leckenby, J. (1) On the sandstones and shales of the oolites of Scarborough, with descriptions of some new species of fossil plants. Quarterly Journ. of the Geol.nbsp;Soc. of Lond., vol. 20 (1864), p. 74 seq.

Lesquereux, Leo. (1) Description of the Coal Flora of the carboniferous formation in Pennsylvania and throughout the United States. Second Geological Survey ofnbsp;Peftnsylvania, Report of Progress P. Harrisburg, vols. i and 2 (1880), vol. 5nbsp;(1884).

(2) nbsp;nbsp;nbsp;On a branch of Cordaites bearing fruit. Proceedings of the American Philosoph.

(4) nbsp;nbsp;nbsp;David Dale Owen�s Second Report of a Geological Reconnaissance of the middle

(5) nbsp;nbsp;nbsp;Land plants recently discovered in the Silurian rocks of the United States. Pro

Lindley, J. and Hutton. (1) The fossil Flora of Great Britain, vol. i (1831-32), vol. 2

liink. (1) Ueber den Ursprung der Steinkohlen und Braunkohlen nach mikroskopischen Untersuchungen. Abhandl. d. Berliner Akad., 1838, p. 33.

Ludwig, R. (1) Calamitenfr�chte aus dem Spatheisenstein bei Hattingen an der Ruhr. Palaeontographica, vol. 10 (1861), p. ll seq.

(2) nbsp;nbsp;nbsp;Fossile Pflanzen aus dem tertiaren Spatheisenstein von Montabaur. Palaeonto

(3) nbsp;nbsp;nbsp;Zur Palaontologie des Urals. Palaeontographica, vol. 10 (1861), p. 17 seq.

Lyell, Ch. (1) Second visit to the United States of North America, sec. ed., vol. 2

M�Coy, F. (1) On the fossil Botany and Zoology of the rocks associated with the coal of Australia. Annals and Magazine of Nat. Hist., vol. 20 (London, 1847), p. 145nbsp;seq.

Mahr. (1) Ueber Sphenophyllum Thonii, eine neue Art aus dem Steinkohlengebirge von Ilmenau. Zeitschrift d. deutschen geolog. Gesellschaft, vol. 20 (1868), p. 433.nbsp;Marion, A. F. F. (1) Sur les caract�res d�une Conif�re tertiaire voisine des Damma-r�es (Doliostrobus Sternbergii). Comptes rendus de I�Acad. de Paris, vol. 99nbsp;(1884), p. 821.

(2) Description des plantes fossiles des calcaires marneux de Ronzon (Haute Loire). Annales des Sc. Nat., s�r. 5, vol. 14 Bot. (1872), p. 326 seq.

Munier-Chalmas. (1) Observations sur les Algues calcaires appartenant au groupe des Siphon�es verticill�es (Dasyclad�es Harv.) et confondues avec les Foraminif�res.nbsp;Comptes rendus hebd. des s�ances de VAcad. des Sc., vol. 85 (1877), pp. 814-817.nbsp;Uebersetzung in bot. Ztg., 1879,/. 165.

(2) Observations sur les Algues calcaires confondues avec les Foraminif�res et appurtenant au groupe des Siphon�es dichotomes. Bull, de la Soc. G�ol. de France, 3 s�r. vol. 7, p. 661.

Ifathorst, A. G. (1) Om spamp;r af namp;gra evertebrerade djur m. m. ock deras palae-ontologiska betydelse. Kongl. Svenska Akademiens Ilandlingar, vol. 18, n. 7 (1881).

(2) nbsp;nbsp;nbsp;Bidrag til Sveriges fossil Flora. Kongl. Svenska Vetenskaps-Akad. Handlingar,

(3) nbsp;nbsp;nbsp;Bidrag til Sveriges fossil Flora. 11. Floran vid Hoganas och Helsingborg. Kongl.

(4) nbsp;nbsp;nbsp;Om Floran i Skamp;nes kolf�rande Bildningar. (i) Floran vid Bjuf. Sveriges Geolo-

(5) nbsp;nbsp;nbsp;Nigra anmarkningar om Williamsonia, Carr. �fversigt af Kongl. Vetenskaps-

(6) nbsp;nbsp;nbsp;Beitrage zur fossilen Flora Schwedens. Stuttgart, 1878. German edition of No. 2

with various alterations; table IV contains the supposed fruits of Sagenopteris, which are wanting in the Swedish original.

(7) nbsp;nbsp;nbsp;Om Spirangium och dess Forekomst i Skanes kolf�rande Bildningar. �fvers. af

Kongl. Vet.-Akademiens F�rhandlingar, 1879.�Sveriges Geologiska Undersokning Afhandlingar, ser. C, n. 36, 1879. A notice of it appeared in the Botanischesnbsp;Centralblatt, vol. l (1880), p. 293.

(8) nbsp;nbsp;nbsp;Nagra anmarkningar om Williamsonia, Carr. �fversicht af Kongl. Vetenskaps-

Ifaumann, C. F. (1) Ueber den Quincunx aJs Cesetz der Blattstelhing bei Sigillaria und Lepidodendron. Neues Jahrbuch f. Min. Geogn. Geol. u. Petrefactenkunde vonnbsp;Leonhard und Bronn. Jahrgang 1842, p. 410 seq.

TTewberry, J. S. (1) Descriptions of some peculiar screwiike fossils from the Chemung rocks. Annals of the New York Academy of Sciences, late Lyceum of Naturalnbsp;History, vol. 3 (1885), p. 217.

Vol. I. Pt. I. Rajmahal series in the Rajmahal hills, by T. Oldham and Morris (1863). Calcutta, 1880.

Pt. 11. Jurassic Rajmahal FI. in the Rajmahal hills, by Ottok. Feist-mantel (1877).

Pt. III. Liassic FI. of the Rajmahal group from Golapilli near Ellore, South Godavary, by O. Feistmantel (1877).

Pt. IV. Upper Gondwana flora of the outliers of the Madras coast, by O. Feistmantel (1879).

Pt. 11. Flora of the Jabalpur Group in the S. Narbada region, by O. Feistmantel (1877).

11. Flora of the Damuda and Panchet Divisions, by O. Feistmantel. Calcutta, 1880-81.

Eeinscli, P. P. (1) Neue Untersuchungen liber die Mikrostruktur der Steinkohle etc., 1881.

Renault, Bernard. (1) Stnccture compar�e de q^^elques tiges de la Flore carbonifere.

. (2) Cours de Botanique fossile, Annie I (1881), II (1882), III (1883), IV (1885).

(3) nbsp;nbsp;nbsp;Renault et C. Eg. Bertrand. Grilletia Sphaerospermii, Chytridiacee fossile du

(4) nbsp;nbsp;nbsp;Recherches sur les v�g�taux silicifi�s d�Autun et de St. Etienne; Etude du genre

Botryopteris. Ann. des sc. nat.. Bot., s�r. 6, vol. l (1875), p. 220 seq., tt. 10, ii. .

(5) nbsp;nbsp;nbsp;Recherches sur la fructification de quelques v�g�taux provenant des gisements

silicifi�s d�Autun et de St. �tienne. Ann. des. sc. nat.. Bot., s�r. 6, vol. 3 (1876), p. 5 seq., tt. 1-4.

(6) nbsp;nbsp;nbsp;Recherches sur les v�g�taux silicifi�s d�Autun. II. Etude du genre Myelopteris.

M�m. pr�sent�spar div. savants a VAcad�mie de Paris, vol. 22 (1875), n. 10.

(7) nbsp;nbsp;nbsp;�tude de quelques v�g�taux silicifi�s des environs d�Autun. Ann. des sc. natur.,

(8) nbsp;nbsp;nbsp;Renault et Q-rand�Eury. Recherches sur les v�g�taux silicifi�s dl A titun. I. Etude

du Sigillaria spinulosa. M�m. pr�s. par div. savants a 1 Acad�mie de Paris, vol. 22 (1875), n. 9.

(9) nbsp;nbsp;nbsp;Sur les fructifications des Sigillaires. Comptes rendus des s�ances de 1�Acad. d. sc.,

(10) nbsp;nbsp;nbsp;�tude sur les Stigmaria, rhizomes et racines de Sigillaires. Annales des sciences

(11) nbsp;nbsp;nbsp;Renault et ZeiUer. Sur quelques Cycad�es houill�res. Comptes rendus de 1�Acad.

INDEX OF LITERATURE.

(12) nbsp;nbsp;nbsp;Kenault et Zeiller. Sur un nouveau genre de fossiles v�g�taux. Comptes rendus

(13) nbsp;nbsp;nbsp;Recherches sur les v�g�taux fossiles du genre Astromyelon. Annales des sciences

(14) nbsp;nbsp;nbsp;Nouvelles recherches sur Ie genre Astromyelon. M�moires de la soc. des sciences

(15) nbsp;nbsp;nbsp;Recherches sur quelques Calamodendr�es et sur leurs af�init�s probables. Comptes

(16) nbsp;nbsp;nbsp;Recherches sur 1 organisation des Sphenophyllum et des Annularia. Ann. des

(17) nbsp;nbsp;nbsp;Sur les fructifications des Calamodendrons. Comptes rendus de 1�Acad. de Paris,

(18) nbsp;nbsp;nbsp;Sur les fructifications miles des Arthropitus et des Bornia. Comptes rendus de

(19) nbsp;nbsp;nbsp;Sur Ie genre Bornia, F. R�m. Comptes rendus de 1�Acad. des sc., vol. 102, 7 Juin,

(20) nbsp;nbsp;nbsp;Nouvelles recherches sur la structure des Sphenophyllum et sur leurs affinit�s

botaniques. Annales des sciences naturelles, s�r. 6, vol. 4 {1877), p. 277 seq.

(21) nbsp;nbsp;nbsp;Renault et Zeiller. Sur des Mousses de 1��poque houill�re. Comptes rendus de

Reuss, A. E. (1) Die Versteinerungen der b�hmischen Kreideformation, 1845-1848. Richter, R. (1) Der Kulm in Th�ringen. Zeitschrift d. deutsch. geol. Gesellschaft, Bd.nbsp;16 (1864), p. 155 seq.

von Roehl. (1) Fossile Flora der Steinkohlenformation Westphalens, einschliesslich Piesberg bei Osnabr�ck. Palaeontographica, vol. 18 (1868-1869), P- i seq.nbsp;Romer, A. (1) Beitrage zur geologischen Kenntniss des nordwestlichen Harzgebirges.

2. nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;IIInbsp;nbsp;nbsp;nbsp;(1854), p. 69nbsp;nbsp;nbsp;nbsp;seq.

3. nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;Vnbsp;nbsp;nbsp;nbsp;(1855-1858),nbsp;nbsp;nbsp;nbsp;p. I seq,

4. nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;IXnbsp;nbsp;nbsp;nbsp;(1862-1864),nbsp;nbsp;nbsp;nbsp;p. I seq.

5. nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;XIIInbsp;nbsp;nbsp;nbsp;(1866), p. 201 seq.

Royle, J. F. (1) Illustrations of the botany and other branches of the natural history of the Himalayan mountains and of the flora of Cashmere, 1839.

Salter, J. W. On some remains of terrestrial plants in the old red sandstone of Caithness. Quarterly Journ. of the Geol. Soc. of Lond., vol. 14 (1858), p. 72 seq. Sandberger, F. (1) Die Flora der oberen Steinkohlenformation im badischen Schwarz-wald. Verhandl. d. naturwissensch. Vereins in Karlsruhe, Heft I (1864), p. 30 seq.nbsp;de Saporta, G. (1) A propos des Algues fossiles, 1882.

(2) nbsp;nbsp;nbsp;Sap. et Marion. Evolution du rigne v�g�talj Phan�rogames, vol. i. Bibliotheque

scientifique internationalepubl. s. 1. dir. de M. �m. Alglave, vol. 52 (1885).

(3) nbsp;nbsp;nbsp;Sap. et Marion. Evolution du rlgne v�g�tals Cryptogames. Bibliotheque scien-

(4) nbsp;nbsp;nbsp;de Saporta. Pal�ontologie franqaise, s�r. 2, v�g�taux. Plantes jurassiques.

(5) nbsp;nbsp;nbsp;�tudes sur la v�g�tation du sud-est de la France. Part. I, nn. 3, 4. Ann. des sc.

(6) nbsp;nbsp;nbsp;�tudes sur la v�g. du sud-est de Ia France. Part. I, nn. 5, 6. Ann. des sc. nat.,

INDEX OF LFFERATURE.^

(7) nbsp;nbsp;nbsp;�tudes sur la v�g�tation du sud-est de la France. Part II, n. i. Ann. des sc. nat.,

(8) nbsp;nbsp;nbsp;�tudes sur la v�g�tation du sud-est de la France. Part II, n. 3. Ann, des sc. nat.,

(9) nbsp;nbsp;nbsp;Prodrome d�une flore fossile des travertins anciens de S�zanne. M�moires de la

(10) nbsp;nbsp;nbsp;Le monde des plantes avant l�apparition de 1�homme, 1879.

(11) nbsp;nbsp;nbsp;Observations sur la nature des v�g�taux r�unis dans le group� des N�ggerathia.

(12) nbsp;nbsp;nbsp;Les Organismes pfobl�matiques des anciennes mers. Paris, 1884.

(13) nbsp;nbsp;nbsp;Nouveaux documents relatifs k des fossiles v�g�taux et k des traces d�invert�br�s

associ�s dans les anciens terrains. Buil. de la Soc. Bot. de France, s�r. 3, vol. 14 (1886), p. 407 seq.

Schenk, A. (1) Beitrdge zur Flora der Vorivelt, IV. Die Flora der nordwestdeutschen Wealdenformation. Palaeontographica, vol. 19 (1874),/. 203 seq.

(2) nbsp;nbsp;nbsp;Richthofen, China. Bd. 4. Pflanzliche Versteinerungen v. A. Schenk. Berk, 1883.

(3) nbsp;nbsp;nbsp;Die fossile Flora der Grenzschichten des Keupers und Lias Frankens, 1868.

(4) nbsp;nbsp;nbsp;Beitrage zur Flora der Vorwelt, III. Die fossilen Pflanzen der Wernsdorfer Schich

(5) nbsp;nbsp;nbsp;Ueber die Pflanzenreste des Muschelkalkes von Recoaro, in E. W. Benecke, Geo-gnostisch-palaontologische Beitrage. Bd. 2, Heft l (1868), p. 71 seq.

(6) nbsp;nbsp;nbsp;Ueber einige in der Braunkohle Sachsens vorkommende Pflanzenreste. Botan.

(7) nbsp;nbsp;nbsp;Ueber die Flora der schwarzen Schiefer von Raibl. Wiirzburger naturwiss. Zeit-

(8) nbsp;nbsp;nbsp;Ueber die Gattungen Elatides, Heer, Palissya, Endl., Strobilites, Schpr. Englers bot.nbsp;Jahrb�cher f. Systematik, Pflanzengeschichte und Pflanzengeographie, vol. 5 (1884),nbsp;P- 341-

(9) nbsp;nbsp;nbsp;Ueber Medullosa elegans. Englers bot. Jahrb�cher f. Systematik, Pflanzen

(10) nbsp;nbsp;nbsp;Ueber die Fruchtstande fossiler Equisetineen. Botan. Zeitung, Bd. 34 (1876),

(11) nbsp;nbsp;nbsp;Die wahrend der Reise des Grafen Bela Sz�chenyi in China gesammelten fossilen

(8) Schimper et Mougeot. (i) Monographie des plantes fossiles du gres bigarr� de la chaine des Vosges, Leipzig, 1844.

(4) Les v�g�taux fossiles du terrain de transition des Vosges. (Terrain de Transition des Vosges par J. R�chlin-Schlumberger et W. Ph. Schimper.) Strassburg, 1862.nbsp;von Schlotheim, E. (1) Die Petrefactenkunde auf ihrem jetzigen Standpunkte, 1820�nbsp;Nachtrage, Abth. I u. II, 1822-1823.

Schl�ter, A. (1) Coelotrochium Decheni, eine Foraminifere aus dem Mitteldevon.

Schmalhausen, J. (1) Beitrage zur Juraflora Russlands. M�m. de 1�Acad. imp. des sc. de St. P�tersbourg, s�r. 7, vol. 27, n. 4 (1879).

(2) Die Pflanzenreste der Steinkohlenformation am �stlichen Abhange des Uralgebirges.

M�m. de FAcad. imp. des sciences de St. P�tersbourg, s�r 7, vol. 31, n. 13 (1883).

(8) Die Pflanzenreste aus der Ursastufe im Flussgeschiebe des Ogur in Ostsibirien. M�langes physiques et chimiques tir�es du Buil. de 1�Acad. imp. des sciences denbsp;St. P�tersbourg, vol. 9 (1876), p. 625 seq.

INDEX OF LITERATURE.

Schmid, E. B. und Schleiden. (1) Die geognostischen Verhaltnisse des Saalthals bei Jena, 1846.

Schmitz, Er. (1) Fruchtrest aus der Steinkohlenformation. Sitzungsbericht der nie-derrhein. Gesellschaft fiir Natur- und HeiJkunde 2U Bonn, 14 Juli, 1879.

Schultze, E. Ueber das Vorkommen wohlerhaltener Cellulose in Braunkohle und Steinkohle. Monatsber. der Berliner Akad., Jahrg. 21 (1855), p. 676 seq.nbsp;Schweinfurth, G. (1) Zur Beleuchtung der Frage �ber den versteinerten Wald.

Graf zu Solms, H. (1) Die Coniferenformen des deutschen Kupferschiefers und Zech-steins. Palaontologische Abhandlungen von Dames und Kayser, vol. 2, Heft 2, Berlin, 1884.

Stefani. (1) Vorlaufige Mittheilung iiber die rhatischen Fossilien der apuanischen Alpen (Bactryllium). Verhandl. d. k. k. geol. Reichsanstalt zu Wien {1882), p. 96 seq.nbsp;Steinhauer, H. (I) On fossil reliquia of unknown vegetables in the coal strata. Transactions of the American Philosophical Society held at Philadelphia, vol. l, new ser.nbsp;(1818), p. 265 seq. (The portion on Stigmaria was reprinted in Bindley undnbsp;Hutton, fossil Flora, vol. l, 31-36.)

Steinmann, G. (1) Zur Kenntniss fossiler Kalkalgen (Siphoneen). Neues Jahrbuch f. Mineralogie, Geologie und Palaontologie, Bd. 2 (1880), p. 130 seq.

(2) Referat iiber Munier Chalmas 2. Neues Jahrb. f. Mineralogie, Geognosie undnbsp;Palaontologie (1882), p. 321.

Stenzel, C. G. (1) Ueber die Staarsteine. Nova Acta Leop. Carol., vol. 24 (1854), p. 823 seq.

(2) nbsp;nbsp;nbsp;Ueber Farnwurzeln aus dem Rothliegenden. Nova Acta Leop. Carol., vol. 26, P. l

(3) nbsp;nbsp;nbsp;Rhizodendron Oppoliense, Gopp. Erganzungsheft zum 63. Jahresbericht der schle-

Graf von Sternberg, Caspar. (1) Versuch einer geognostisch botanischen Darstellung der Flora der Vorwelt. Leipzig., 1821-1838.

(2) Beschreibung der Huttonia spicata, einer neuen fossilen Pflanze. Verhandlungen der Gesellschaft des vaterlandischen Museums in Bohmen. Jahrgang 1837.nbsp;Beilage C zur Rede des Prasidenten in der Versammlung vom 5. April, 1837, t. I.nbsp;Sterzel, J. T. (1) Ueber Scolecopteris elegans Zenk. und andere fossile Reste aus demnbsp;Hornstein von Altendorf bei Chemnitz. Zeitschr. der deutschen geologischennbsp;Gesellschaft, vol. 32 (1880), p. i seq.

(2) nbsp;nbsp;nbsp;Die fossilen Pflanzen des Rothliegenden von Chemnitz. Fiinfter Bericht der

(3) nbsp;nbsp;nbsp;Ueber die Fruchtahren von Annularia sphenophylloides Zenker etc. Zeitschr. der

(4) nbsp;nbsp;nbsp;Palaontologischer Charakter der oberen Steinkohlenformation und des Roth

liegenden im erzgebirgischen Becken. Siebenter Bericht der Naturf. Gesellschaft zu Chemnitz (1881).

Stiehler. (1) Brief an Herrn von Carnall. Zeitschr. der deutschen geologischen Gesellschaft, vol. 2 (1850), p. 181.

Stokes, Ch. (1) Notice respecting a piece of recent wood partly petrified by carbonate of lime with some remarks on fossil woods. Transactions of the Geol. Soc. ofnbsp;Lond., ser. 2, vol. 5, London, 1840.

Strasburger, Eduard. (1) Ueber Scolecopteris elegans, Zenk. Jenaer Zeitschrift f. Naturw., vol. 8 (1874), p. 88 seq.

INDEX OF LITERATURE.

Stiir, D. (1) Beitriige zur Kenntniss der geologischen Verhaltnisse von Raibl und Kaltwasser. Jahrb. d. k. k. geol. Reichsanstalt zu Wien, Bd. 18 (1868).

(2) nbsp;nbsp;nbsp;Ueber die in Flotzen reiner Steinkohle enthaltenen Steinrundmassen und Torf-

spharosiderite. Jahrb. der k. k. geol. Reichsanstalt zu Wien, vol. 35 (1885), p. 613 seq.

(3) nbsp;nbsp;nbsp;Die Carbonflora der Schatzlarer Schichten. I. Fame. Abh. d. k. k. geol. Reichs

(4) nbsp;nbsp;nbsp;Zur Morphologic und Syste/natik der Culm- und Carbonfarne. Sitzber. d. k. k.

(5) nbsp;nbsp;nbsp;Die Culmjlora der Ostrauer und Waldenburger Schichten. Abh. d. k. k. geol.

(6) nbsp;nbsp;nbsp;Die Culmjlora des mdhrisch-schlesischen Dachschiefers. Abh. d. k. k. geol.

(7) nbsp;nbsp;nbsp;Die obertriadische Flora der Lunzer Schifhten und des bituminosen Schiefers vonnbsp;Raibl. Sitzber. d. k. Akad. d. Wissensch. zu Wien, 1885, I. Marzheft.

(8) . Zur Morphologie der Calamarien. Sitzber. d. k. Akad. d. Wissensch. zu Wien,

(9) nbsp;nbsp;nbsp;1st das Sphenophyllum in der That eine Lycopodiacee ? Jahrb. d. k. k. geol.

(10) Sphenophyllum als Ast auf einem Asterophylliten. Verhandl. d. k. k. geol. Reichsanstalt zu Wien, Jahrgang 1878, p. 327 seq.

Temme. (1) Der am Piesberg gefundene und aufgestellte Wurzelstock einer Sigillaria. Sechster Jahresbericht des naturwissenschaftl. Vereins zu Osnabriick (1885),nbsp;p. 266, c. tab.

Thompson, D�Arcy W. (1) Notes on Ulodendron and Halonia. Transact, of the Edinburgh Geological Society, vol. 3, pt. 3 (1880), p. 341 seq.nbsp;van Tieghem, Ph. (1) Sur le ferment butyrique (Bacillus Amylobacter) k I�epoquenbsp;de la houille. Comptes rendus hebd. de I�Acad. de Paris, vol. 89 (1879), p. 1102nbsp;seq.

(3) nbsp;nbsp;nbsp;Sur quelques points de 1'anatomie des Cryptogames vasculaires. Bttll. de la Soc.

(2) nbsp;nbsp;nbsp;Beitrag zur naheren Kenntniss des Leithakalkes. Denkschriften der k. k. Akad. d.

(3) nbsp;nbsp;nbsp;Die fossile Flora von Kumi auf der Insel Euboea. Denkschriften der k. k. Akad. d.

(4) nbsp;nbsp;nbsp;Iconographia plantarum fossilium. Denkschriften der k. k. Akad. d. Wissensch. zu

(5) nbsp;nbsp;nbsp;F. Unger wnd R. Richter. Beitrag zur Palaontologie des Thiiringer Waldes.

(7) nbsp;nbsp;nbsp;Der versteinerte Wald bei Cairo. Sitzber. der mathem.-naturw. Classe der Wiener

(8) nbsp;nbsp;nbsp;Ein fossiles Famkraut aus der Ordnung der Osmundaceen nebst vergleichendennbsp;Skizzen iiber den Bau des Farnstammes. Denkschriften der k. k. Akad. dernbsp;Wissensch. zu Wien. Mathem.-naturw. Classe, vol. 6 (1854), p. I37 seq.

(9) nbsp;nbsp;nbsp;Ueber die Struktur der Calamiten und ihre Rangordnung im Gewachsreich. Flora,nbsp;Jahrgang 23, Bd. 2 (1840), p. 654 seq. Unger�s drawings were published for the firstnbsp;time in Petzholdt�s Calamiten und Steinkohlenbildung, tt. 7, 8 ; some of the figuresnbsp;were reproduced by Goppert in his Permische Flora.

(10) nbsp;nbsp;nbsp;Anthracitlager in Karnthen. Sitzber. der k. k. Akad. d. Wissensch. zu Wien.

C c a

Vanuxem, Lardner. (1) Natural History of New York, Geology, Part III (1842). Vater, H. (1) Fossile H�lzer der Phosphoritlager Braunschweigs. Zeitschrift dernbsp;deutschen geol. Gesellsch., vol. 36 (1884), p. 783 seq.

Waloh, J. E. J. (1) Die Naturgeschichte der Versteinerungen zur Erlauterung der Knorrischen Sammlung von Merkwiirdigkeiten der Natur., vol. l, N�rnberg, 1773.nbsp;Weisa, Cli. E. (1) Fossile Flora der jUngsten Steinkohlenformation und des Rothlie-genden im Saar-Rheingebiet. Bonn, 1869.

(2) nbsp;nbsp;nbsp;Einige Carbonate aus der Steinkohlenformation. Jahrb. d. k. preuss. geol. Landes-

(3) nbsp;nbsp;nbsp;Zur Flora der altesten Schichten des Harzes. Jahrb. d. k. preuss. geol. Landes-

(4) nbsp;nbsp;nbsp;Ueber Lomatophloios macrolepidotus, Goldenb., Zeitschrift der deutschen geol.

Gesellsch., Bd. 33 (1881), p. 354. See also Botan. Centralblatt, vol. 8 (1881), p. l57-

(5) nbsp;nbsp;nbsp;Beitrdge zur fossilen Flora III. Steinkohlen-Calamarieji II. Abhandl. zur geolo-

gischen Specialkarte von Preussen und den Thiiringischen Staaten, vol. 5, Heft 2,/. 87 seq. Berlin, 1884.

(6) nbsp;nbsp;nbsp;Beitrdge zur fossilen Flora I. Steinkohlen-Calatnarien mit besonderer Beriicksich-

tigung ihrer Fructificationen. Abhandl. zur geol. Specialkarte von Preussen, vol. 2, Heft I (1876).

(7) nbsp;nbsp;nbsp;Vorlaufige Mittheilungen uber Fructificationen der fossilen Calamarien. Zeitschrift

(8) nbsp;nbsp;nbsp;Sphenophyllum, Asterophyllites, Calamites. Neues Jahrbuch fur Min., Geol. u.

(9) nbsp;nbsp;nbsp;Ueber eine Buntsandsteinsigillaria und deren nachste Verwandte. Jahrbuch der

�Williamson, W. C. (1) On the organisation of the fossil plants of the coal-measures.

Ft. II, Lycopodiaceae, Lepidodendreae and Sigillarieae. Philos. Transact., 1872,/. 197 seq.

Pt. VII. Myeloptcris,Psaronius, Kaloxylo7i. Philos. Transact., 1876,/. i seq. Pt. VIII. Ferns, Gyinnospermous Stems and Seeds. Philos. Transact., 1877,nbsp;p. 213 seq.

(2) nbsp;nbsp;nbsp;On some undescribed tracks of invertebrate animals from the Yoredale rocks and

on some inorganic phenomena produced on tidal shores simulating plant remains. Memoirs of the Literary and Philosophical Society of Manchester, ser. 3, vol. 10nbsp;(1885), p. 19 seq.

(3) nbsp;nbsp;nbsp;Contributions towards the history of Zamia gigas, Lindl. et Hutt. Tra7isact. of the

(4) nbsp;nbsp;nbsp;On the structure and affinities of the plants hitherto known as Sternbergiae.

Memoirs of the Literary and Philosophical Society of Manchester, ser. 2, vol. 9 (1851), p. 340.

(5) nbsp;nbsp;nbsp;Williamson, W. C. et M. Hartog. Les Sigillaires et les L�pidodendr�es.

(6) nbsp;nbsp;nbsp;A 7nonograph on the morphology and histology of SHgtttaria Jicoides. Palaeonto-graphical Society, 1887.

(7) nbsp;nbsp;nbsp;On the structure of the woody zone of an undescribed form of Calamite. Memoirs

of the Literary and Philosophical Society of Manchester, ser. 3, vol. 4 (1869), P- 155 seq.

(8) nbsp;nbsp;nbsp;On a new form of Calamitean strobilus from the Lancashire Coal-measures.

Memoirs of the Literary and Philosophical Society of Manchester, ser. 3, vol. 4 (1870), p. 248 seq.

(9) nbsp;nbsp;nbsp;On the organisation of Volkmannia Dawsoni. Memoirs of the Literary and Philo

(10) Contributions towards the history of Zamia gigas, Ldl. et Hutt. Transactions ofnbsp;the Linnean Society, vol. 26 (1868),nbsp;nbsp;nbsp;nbsp;663 seq.

Witham of Lartington, W. (1) The internal structure of fossil vegetables found in the carboniferous and oolitic deposits of Great Britain, Edinburgh, 1833.

Wright, Berlin H. (1) Notes on the Geology of Yates County, New York. Thirty-fifth Annual Report on the New York State Museum of Nat. Hist. (1884), p. 195 seq.

W�nsoh, E. A. (1) Carboniferous fossil trees imbedded in Trappean ash in the isle of Arran. Seemann�s Journ. of Botany, vol. 5 (1867), p. 305.

Zeiller, E.. nbsp;nbsp;nbsp;(1) Sur des traces dTnsectes simulant des empreintes v�g�tales. Bulletin de

(2) nbsp;nbsp;nbsp;Observations sur quelques cuticules fossiles. Ann. des sc. nat. (Bot.), s�r. 6, vol. xiii.

(3) nbsp;nbsp;nbsp;V�g�taux fossiles du terrain houiller de la France. Extrait du tome IV de I�expli-

(4) nbsp;nbsp;nbsp;Note sur quelques plantes fossiles dq terrain permien de la Corr�ze. Bulletin de la

(5) nbsp;nbsp;nbsp;Note sur le genre Mariopteris. Bulletin de la Soc. G�ol. de France, s�r. 7, vol. 3

(6) nbsp;nbsp;nbsp;Sur quelques genres de Foug�res fossiles noicvellement cr��s. Ann. des sc. nat., s�r.

(7) nbsp;nbsp;nbsp;Fructifications de Foug�res houUl�res. Ann. des sc. nat, s�r. 6, vol. xvi. (1883).

(8) nbsp;nbsp;nbsp;Sur les affinit�s du genre Laccopteris. Bulletin de la Soc. Bot. de France, vol. 32

(9) nbsp;nbsp;nbsp;Note sur quelques troncs de Foug�res fossiles. Bulletin de la Soc. G�ol. de France,

(10) nbsp;nbsp;nbsp;Note sur quelques troncs de Foug�res fpssiles. Bulletin de la Sqc. G�ol. de France,

(11) nbsp;nbsp;nbsp;Observations sur les genres Ulodendron et Bothrodendron. Bulletin de la Soc.

(12) nbsp;nbsp;nbsp;Cbnes de fructification des Sigillaires. A,nn. des sc. 7iat., s�r. 6, vol. xix. (1884),nbsp;p. 256 seq.

(13) nbsp;nbsp;nbsp;Note sur la Flore du Bassin houiller de T�te (Region du Zamb�se). Annales des

Zittel, K. A. (1) Edandbuch der Paldontologie, Bd. II, Lieferung I (1879) und II (1880), bearbctfet vo7i ]V. Ph. Schi77tper. Lieferu7tg III (*884) 7i7id IV (1885),nbsp;bearbeitet V07i A. Schenk.

INDEX.

jtft* .,-i-j-lt;- quot;ji gt;;’-vgt;i ,.,=t'j ..quot;•gt;. lt;.^\ji^-.

-i'-w nbsp;nbsp;nbsp;'.^•^. ’^:

'. nbsp;nbsp;nbsp;’ 'iKgt;.i :.';

■ .' .',.'-'iilv,••?'.;!;■') j/ ;.i c^'Hits^;,.., nbsp;nbsp;nbsp;, .': : '

■«• ■.- nbsp;nbsp;nbsp;• r y ' , ^ ■}* ‘^\i - -‘i ■,

/ nbsp;nbsp;nbsp;;■nbsp;nbsp;nbsp;nbsp;Mnbsp;nbsp;nbsp;nbsp;.-v

^'-.....gt;•gt;:■ ■■:..■■,., nbsp;nbsp;nbsp;... V

..';*jf v'. '.-

^ ■■■ '■■'•; . ' ■■•’ .1 ■. ..

. ... . ' ' .' 1 ' ,' •

'-^ n' ; •■■. ■VÜ; ;(*•;?,,•!

.......

J. v\ V .” nbsp;nbsp;nbsp;ï;.nbsp;nbsp;nbsp;nbsp;■nbsp;nbsp;nbsp;nbsp;.. , ..nbsp;nbsp;nbsp;nbsp;,■_ 'nbsp;nbsp;nbsp;nbsp;,,nbsp;nbsp;nbsp;nbsp;,,,

‘ nbsp;nbsp;nbsp;'■;V ■ 'nbsp;nbsp;nbsp;nbsp;■ ■

c.'5,’-. •.•;■•;■: ■'.■t rM J;':r. Jr .'igt;':-.■irJ. ■,'!.''

•”-'■* ;'••■''• ■ ■•■' -J ri . .' J.'..';/.gt;'i.'. ; nbsp;nbsp;nbsp;.^,^gt;• atójjfi

\5-Fi tr. V.-• ■' - ■•■■-■lt; ' • ■•r'4?.!

. nbsp;nbsp;nbsp;■nbsp;nbsp;nbsp;nbsp;:'nbsp;nbsp;nbsp;nbsp;■nbsp;nbsp;nbsp;nbsp;;nbsp;nbsp;nbsp;nbsp;'nbsp;nbsp;nbsp;nbsp;'v-' ■

.. nbsp;nbsp;nbsp;•iJ!'-?.;)* ;!quot;rnbsp;nbsp;nbsp;nbsp;V .; .;•: i,j ■

' ■ ... '

• ' I nbsp;nbsp;nbsp;^nbsp;nbsp;nbsp;nbsp;.nbsp;nbsp;nbsp;nbsp;•. rt, .nbsp;nbsp;nbsp;nbsp;^nbsp;nbsp;nbsp;nbsp;^nbsp;nbsp;nbsp;nbsp;.nbsp;nbsp;nbsp;nbsp;•nbsp;nbsp;nbsp;nbsp;'.nbsp;nbsp;nbsp;nbsp;•.nbsp;nbsp;nbsp;nbsp;.nbsp;nbsp;nbsp;nbsp;.nbsp;nbsp;nbsp;nbsp;•

INDEX.

Cfat�nbon (J)v�00*

History of Botany (1530-J 860). By Julius von Sachs. Authorised Translation, by H. E. F. Garnsey, M.A. Revised by Isaac Bayley Balfour,nbsp;M.A., M.D., F.R.S. Crown 8vo. lor.

Comparative Anatomy of the Vegetative Organs of the

Phanerogams and Ferns. By Dr. A. De Bary. Translated and Annotated by F. O. Bower, M.A., F.L.S., and D. H. Scott, M.A., Ph.D., F.L.S.nbsp;Royal 8vo, half morocco, 2s. 6d.

Outlines of Classification and Special Morphology of Plants.

A new Edition of Sachs� Text-Book of Botany, Book II. By Dr. K. Goebel. Translated by PI. E. F. Garnsey, M.A., and Revised by Isaac Bayleynbsp;Balfour, M.A., M.D., F.R.S. Royal 8vo, half morocco, �i u.

Lectures on the Physiology of Plants. By Julius von Sachs.

Translated by H. Marshall Ward, M.A., F.L.S. Royal 8vo, half morocco. �l iir. 6d.

Comparative Morphology and Biology of Fungi, Myce-

tozoa and Bacteria. By Dr. A. De Bary. Translated by H. E. F. Garnsey, M.A., and Revised by Isaac Bayley Balfour, M.A., M.D., F.R.S, Royalnbsp;8vo, half morocco, 2s. 6d.

Lectures on Bacteria. By Dr. A. De Bary. Second Improved Edition. Translated by H. E. F. Garnsey, M.A., and Revised by Isaac Bayleynbsp;Balfour, M.A., M.D., F.R.S. Crown 8vo. 6s.

Vol. IV. Parts XIII. i2r. 6d.; XIV. 13^. 6d.; XV. tor. 6d. ; XVI. itt the press. Vol. V. Part XVII. lor. 6d.

ITffnbon:

HENRY FROWDE

FOSSIL BOTANY

INI'RODUCTION to palaeophytology

H. Graf zu SOLMS-LAU BACH

HENRY E. F. GARNSEY, M.A.

ISAAC BAYLEY BALFOUR, M.A., M.D., F.R.S.

O;cfor�

AT THE CLARENDON PRESS

PRINTED AT THE CLARENDON PRESS

PREFACE

PREFACE TO THE ENGLISH EDITION

c: o N T E N T S

CONTENTS.

ERRATA

PALAEOPHYTOLOGY.

INTRODUCTION.

II.

37

^ens.

P,

the

earnestness.

that he

^'Snyanus ^ckn,

Passi:

be

animal is

The

III.

equoia

IV.

CVCADEAE, MEDULLOSEAE.

� Carruthers (4), t. 59, f. 6.

CORDAITEAE.

^ Renault (1).

^^rand�Eury(l),t.2,,f,5.

VIL

FILICES.

.M

VIII.

EQUrSETACEAE, MARSILIOIDEAE, TRAQUAIRIA, SPOROCARPON.

, j, w, ti.li. .V, t. .7. nbsp;nbsp;nbsp;3^*

X.

XI.

XII.

Part I, p. m.

XIII.

* Weiss (6), t. 9, f. I.

XIV.

XVI.

LIST OF PUBLICATIONS.

INDEX OF LITERATURE.

INDEX OF LITERATURE.

INDEX OF LFFERATURE.^

INDEX OF LITERATURE.

INDEX OF LITERATURE.

C c a

INDEX.

57- ,

173-

¥B

■«• ■.- nbsp;nbsp;nbsp;• r y ' , ^ ■}* ‘^\i - -‘i ■,

INDEX.

INDEX.

274.

74-

155-

INDEX.

93-

362, 363-

.395

INDEX.

88.

INDEX.

INDEX.

INDEX.

T.

� nbsp;nbsp;nbsp;gigas, 91 gt; 94-

Cfat�nbon (J)v�00*