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Ill By :iT, rbe iNE, ith NI- om ant m^^^ TT — "■" m •0 I ^ ^ ^1 W «»: 8 ■ ^^^^ • S ^ «0 1 ^ 1 Iri m ^ ^^ ^ ■ W ^ i ? ^ ■^ V ^H ^^^^^H VI s 5 ■ ^^m ^ ^ ^^ '^ 0. u ^ to o 3 c ^ s ii ^ 1^ ? ^ w v> s 1 ^ ^^m2^^^^^^^ ^ ^ «0 «c 1 ^ ^ Q CO ^ ^^^" '^ 5 ■4 W ^^ 0» * £ H HH^I 1:: 0: ^ ^^^^H^^^^^* il si "M 1 \ 1 g ^ S 1 • •9 i i si II i 5 3 5 01O20N30 01OZ0S3W OIOZ031Vd 010203 THE INTERNATIONAL SCIENTIFIC SERIBS 'o^^'^'^^' **•• THE C GEOLOGICAL HISTORY OF PLANTS BY SIE J. WILLIAM DAWSON C. M. O., LL. D., F. R. S., &c. WITH ILLUSTRATION '. • • • - N^^W YORK D. APPLEx.,.^ Af^D COMPANY 1888 COPYEIOHT, 1888, By D. APPLETON AND COMPANY. « t « C < '• 1 •-< j PREFACE. The object of tliis work is to give, in a connected form, a summary of the development of the vegetable kingdom in geological time. To the geologist and botanist the subject is one of importance with reference to their special pursuits, and one on which it has not been easy to find any conveni- ent manual of information. It is hoped that its treat- ment in the present volume will also be found suffi- ciently simple and popular to be attractive to the general reader. In a work of so limited dimensions, detailed descrip- tions cannot be given, except occasionally by way of illustration ; but references to authorities will be made in foot-notes, and certain details, which may be useful to collectors and students, will be placed in notes appended to the chapters, so as not to encumber the text. The illustrations of this work are for the most part original ; but some of them have previously appeared in special papers of the author. J. W. D. February, 1888. •^'T^t^ h COI^TENTS. CHAPTER I. PA6B Preliminary Ideas of Geolooical Chronology and of the Classi- fication OF Plants 1 CHAPTER II. Vegetation of tue Lacrentian and Early Paleozoic — Questions AS TO Alg^ 8 CHAPTER III. The Erian or Dkvonian Forests — Origin of Petroleum— The AoE of Acrogens and Gymnosperms 45 CHAPTER lY. The CARBONiFERotis Flora -Culmination ok the Acrooens — For- mation OF Coal 110 CHAPTER V. The Flora of the Early Mesozoic — Reign of Pines and Cycads . 175 CHAPTER VI. The Reign of Angiosperms in the Later Cretaceous and Early Tertiary or Kainozoic 191 2 Nlf ' 'HWiiniiin'11— tWM • • • Vlll CONTENTS. CHAPTER VII. Plants from the Tertiary to thk Modern Plriod PAGE . 219 CHAPTER VIII. Geneuai., Laws op Origin and Migrations op Plants — Relat'ons OP Recent and Fossil Flouas 287 APPENDIX. I. Comparative View of PALiEozoic Floras .... 273 II. Hekr's Latest Statements on the Greenland Flora . . 281 III. Mineralisation of Fossil Plants 284 IV. General Works on Paleobotany 286 t LIST OF ILLUSTEATIOI^S. PAOB Table op Chronology op Plants .... (Frontispiece.) Protannularia Harkncssii 21 Nematophvton Logani (three Figures) 22, 23 Trail of K!ng-Crab 28 Trail of Carboniferous Crustacean 28 Rusichnitcs 29 PaliPophyciis 30 Astropolithon 31 Carboniferous Rill-mark 33 Cast of Shrinkage Cracks 34 Cone-in cone 36 Buthotrephis Si Silurian Vegetation 40 Brian Plants 49 Protosalvinia 64 Ptilophyton (two Figures) 62, 63 Psilophyton (two Figures) 64, 66 Sphenophyllum 66 Lcpido>'endron 66 Various .. cms 72,73 ArcluTopteris 74 Cauloptcris 75 Megalopteris 76 Calamites 77 Asterophyllites . . , 78 Dadoxylon ,,,... 79 LIST OF ILLUSTRATIONS. fl i ii Species) Cordaites .... Erian Fruits .... Foliage from th(^ Coal -formation Sigillaria! (five Figure.^) . Stigmariie (two Figures) . Vcgt'tiible Tissues . Coals and Erect Trees (two Figures) Lepidodendron Lepidophloios .... Astcropliyllites, &c. . Calamitcs (five Figure.='> . Ferns of the Coal-formaiion (six Figures) Noeggcratliia dispar Cordaites .... Fruits of Cordaites, &c. . Conifers of the Coal-formation (four Trigonocarpum Sternberg! a .... Walfliia imbricatula Foliage of the Jurassic Period . Podozamites .... Salisburia .... Sequoia ..... Populus primieva Stercalia and Laurophyllum Vegetation of the Cretaceous Period Platanus ..... Protophylluni .... Magnolia .... Liriodendron (two Figures) Brasenia Gaylussaccia resinosa Populus balsamifera Fucus PAGE . 81 . 82 . VI 112-114 . 115 . 117 118, 119 . 120 . 121 . 122 123-125 12G-129 . 130 131 132 135 136 137 138 177 178 180 181 191 194 195 19S 199 200 201 207 228 229 230 THE GEOLOGICAL HISTORY OF PLANTS. CHAPTER I. PRELIMINARY IDEAS OF GEOLOGICAL CHRONOLOGY AND OF THE CLASSIFICATION OF PLANTS. The knowledge of fossil plants and of the history of the vegetable kingdom has, until recently, been so frag- mentary that it seemed hopeless to attempt a detailed treatment of the subject of this little book. Our stores of knowledge have, however, been rapidly accumulating in recent years, and we have now arrived at a stage when every new discovery serves to render useful and intelligi- ble a vast number of facts previously fragmentary and of uncertain import. Tlie writer of this work, born in a district rich in fossil plants, began to collect and work at these as a boy, in connection with botanical and geological pursuits. He has thus been engaged in the study of fossil plants for nearly half a century, and, while he has published much on the subject, has endeavoured carefully to keep within the sphere of ascertained facts, and has made it a specialty to collect, as far as possible, what has been published by others. He has also enjoyed opportunities of correspondence or personal intercourse with most of \ a THE GEOLOGICAL HISTORY OF PLANTS. i: the more eminent workers in the subject. No'v. in the evening of his days, he thinks it right to endeavour to place before the world a summary of facts and of his own matured conclusions— feeling, however, that nothing can be final in this matter ; and that he can only hope to sketch the present aspect of the subject, and to point the way to new developments, which must go on long after he shall have passed away. The subject is one which has the disadvantage of pre- supposing some knowledge of the geological history of the earth, and of the classification and structures of mod- ern plants ; and in order that all who may please to read the following pages may be placed, as nearly as possible, on the same level, this introductory chapter will be de- voted to a short statement of the general facts of geological chronology, and of the natural divisions of the vegetable kingdom in their relations to that chronology. The crust of the earth, as we somewhat modestly term that portion of its outer shell which is open to our obser- vation, consists of many beds of rock superimposed on each other, and which must have been deposited succes- sively, beginning with the lowest. This is proved by the structure of the beds themselves, by the markings on their surfaces, and by the remains of animals and plants which they contain ; all these appearances indicating that each successive bed must have been the surface before it was covered by the next. As these beds of rock were mostly formed under water, and of material derived from the waste of land, they are not universal, but occur in those places where there were extensive areas of water receiving detritus from the land. Further, as the distinction of land and watei arises prima- rily from the shrinkage of the mass of the earth, and from the consequent collapse of the crust in some places and ridging of it up in others, it follows that there have, from the earliest geological periods, been deep ocean- GEOLOGICAL CHRONOLOGY. 8 basins, ridpefc. of elevated land, and broad plateaus inter- vening bctweeii the lidges, and which were at some times under water, and ut otlier times land, with many inter- mcdiato phases. The settlement and crumpling of the crust were not continuous, but took place at intervals ; and each such settlement produced not only a ridging up along certain lines, but also an emergence of the i)lains or plateaus. Thus at all times there have been ridges of folded rock constituting mountain-ranges, flat expansions of continental plateau, sometimes dry and sometimes sub- merged, and deep ocean-basins, never except in some of their shallower portions elevated into land. By the study of the successive beds, more especially of those de))Osited h\ the times of continental submer- gence, we obtain a table of geological chronology which expresses the several stages of the formation of the earth's crust, from tnat early time when a solid shell first formed on our nascent planet to the present day. By collecting the fossil remains embedded in the several layers and placing these in chronological order, we obtain in like manner histories of animal and plant life parallel to the physical changes indicated by the beds themselves. The facts as to the sequence we obtain from the study of ex- posures in cliffs, cuttings, quarries, and mines ; and by correlating these local sections in a great number of places, we obtain our general table of succession ; though it is to be observed that in some single exposures or series of exposures, like those in the great caflons of Colorado, or on the coasts of Great Britain, we can often in one locality see nearly the whole sequence of beds. Let us observe here also that, though we can trace these series of deposits over the whole of the surfaces of the continents, yet if the series could be seen in one spot, say in one shaft sunk through the whole thickness of the earth's crust, this would be sufficient for our purpose, so far as the history of life is concerned. ■, -.. ■rt- THE GEOLOGICAL HISTORY OF PLANTS. I The evidence is similar to that obtained by Schlie- mann on the site of Troy, where, in digging through suc- cessive layers of debris, he found the objects deposited by successive occupants of the site, from the time of the Roman Empire back to the earliest tribes, whose flint weapons and the ashes of their fires rest on the original surface of the ground. Lot us now tabulate the whole geological succession with the history of animals and plants associated with it: ANIMALS. Age of Man and Mammalia. Age of Reptiles. Age of Arapliibians and Fishes. Age of Inverte- brates. Age of Protozoa. SYSTEMS OF FORMATIONS. O N O a 'S U4 Modern, Pleistocene, -1 Pliocene, j Miocene, I Eocene. .2 r o N O in o o J p. o N o Cretaceous, i Jiiras.'^ic, Triassic. r Permian, j Carboniferous, I Erian, 1 Silurian, j Ordovician, I Cambrian, I Il'ironian (Upper). Iluronian (Lower), Upper Laurcntian, Middle Laurcntian, Lower Laurcntian. PLANTS. Angiosperms and Palms dominant. Cycads and Pines dominant. Acrogens and Gym- nosperms domi- nant. Protogcns and Algre. It will be observed, since only the latest of the sys- tems of formations in this table belongs to the period of human history, that the whole lapse of time embraced in the table must be enormous. If we suppose the modern period to have continued for say ten thousand years, and each of the others to have been equal to it, we shall re- quire two hundred thousand years for the whole. There is, however, reason to believe, from the great thickness of the formations and the slowness of the deposition of many ^ ! GEOLOGICAL CUROXOLOGY. 5 of them in the older systems, that they must have re- quired vastly greater time. Taking these criteria into account, it has been estimated that the time-ratios for the first three great ages may he as one for the Kainozoic to tiiree for tiie Mesozoic and twelve for the Palaeozoic, with as much for the Eozoic as for the Pala'ozoic. This is Dana's estimate. Another, by Hull and Ilougiiton, gives the following ratios : Azoic, 34*3 per cent. ; Palaeozoic, 42*5 per cent. ; Mesozoic and Kainozoic, 23*2 per cent. It is furtlier held that the modern jwriod is much siiorter than tiie other periods of the Kainozoic, so that our geological table may have to be measured by millions of years instead of thousands. We cannot, however, attach any certain and definite value in years to geological time, but must content our- selves Tvith the general statement that it has been vastly long in comparison to that covered by human history. Bearing in mind this great duration of geological time, and the fact that it probably extends from a period when the earth was intensely heated, its crust thin, and its con- tinents as yet unformed, it will be evident that the con- ditions of life in the earlier geologic periods may have been very different from those which obtained later. When we further take into account the vicissitudes of land and water which have occurred, we shall see that such changes must have produced very great differences of climate. The warm equatorial waters have in all periods, as superficial oceanic currents, been main agents in the diffusion of heat over the surface of the earth, and their distribution to north and south must have been determined mainly by the extent a»id direction of land, though it may also have been modified by the changes in the astronomical relations and period of the earth, and the form of its orbit.* We know by the evidence of * Croll, " Climate and Time." THE GEOLOGICAL IIISTOKY OF PLANTS. n i i i fossil plants that chanp;es of this kind have occurred so great as, on the one hand, to j)ermit the plants of warm temperate re^^ions to exist within the Arctic Circle ; and, on the other, to drive these i)lants into the tropics and to replace them by Arctic forms. It is evident also that in those periods when the continental ureas were largely submerged, there might be an excessive amount of moist- ure in the atmosphere, greatly modifying the climate, in 80 far as plants are concerned. Let us now consider the history of the vegetable king- dom as indicated in the few notes in the right-hand column of the table. The most general subdivision of plants is into the two great series of Cryptogams, or those which have no mani- fest flowers, and produce minute spores instead of seeds ; and Phfcnogams, or those which possess flowers and pro- duce seeds containing an embryo of the future i)lant. The Cryptogams may be subdivided into the following three groups : 1. Thallof/fitis, cellular plants not distinctly distin- guishable into stem and leaf. These are the Fungi, the Lichens, t^nd the Algae, or sea-weeds. 2. Anogens, having stem and foliage, but wholly cel- lular. These are the Mosses and Liverworts. 3. Acrogens, which have long tubular fibres as well as cells in their composition, and thus have the capacity of attaining a more considerable magnitude. These are the Ferns {Filices), the Mare's-tails {Equisetacem), i. i the Club-mosses {Li/copodiacrcB), and a curious little group of aquatic plants called Rhizocarps {RMzocarpem). The Pha3nogams are all vascular, but they differ much in the simplicity or complexity of their flowers or seeds. On this ground they admit of a twofold division : 1. Gymnosperms, or those which bear naked seeds not enclosed in fruits. They are the Pines and their allies, and the Cycads. CLASSIFICATION' OF PLANTS. 2. Atif/iospernis, wliicli product' true fruits enclosing the seeds. In this gnnij) there are two well-marked sub- divisions ditTcriii^ in the structure of the seed and stem. Tlioyare the Endo 36 THE GEOLOGICAL HISTORY OF PLANTS. - kind from the coal-formation of Nova Scotia, which is described in ** Acadian Geology" * (Fig. 12). I have referred to these facts here because they are relatively more important in that older period, which may be named the agt- of Algae, and because their settlement now will enable us to dispense with discussions of this kind further on. The able memoirs of Nathorst and Williamson should be studied by those who desire further information. But it may ba as^^ed, "Are there no real examples of fossil Algaj ? " I believe there are many such, but the diffi- culty is to distinguish them. Confining our- selves to the older rocks, the following may be noted : The genus Bu- thotrephis of Hall, which is characterised as having stems, sub- cylindric or com- pressed, \vith numer- ous branches, which are divaricating and sometimes leaf -like, contains some true Algae. Hall's B. gracilis, from the Siluro-Cambrian, is one of these. Similar plants, referred to the same species, occur in the Clinton and Niagara formations, and a beautiful species, collected by Col. Grant, of Hamilton, and now in the McGill College col- lection, represents a broader and more frondose type of distinctly carbonaceous character. It may be described as follows : Buthotrephis Grant ii, S. N (Fig. 13). — Stems and * Appendix, p. 676, edition of 1878. Fio. 12. — Cono-in-conc concretion (Carbon- iferouB, Nova Sootia), illustrating pre- tended Algee. ,.,.^.n.^.uu.,r^m LAURENTIAN AND EARLY PALEOZOIC. 37 fronds smooth and slightly striate longitudinally, with curved and intermixed stria). kStem thick, bifurcating, the divisions terminating in irregularly pinnate fronds, apparently truncate at the extremities. The quan- tity of carbona- ceons matter pres- ent would indicate thick, though per- haps flattened, stems and dense fleshy fronds. The species Butliotrcphis sub- nodosa and B. jlexuosa, from the Utica shale, are also certain- ly plants, though it is possible, if their structures and fruit were known, some of these might be referred to differ- ent genera. All of these plants have either car- bonacGous matter or produce organ- ic stains on the matrix. The organism Fio. 13. — Buffi of rep /lift Grnnfii, u j»enuinc Alga frum the Siluriun, Ciinuda. diverging with wedge-shaped fronds, described by Hall as Sphenothalhis aiKjustifolius, is alsc -i. plant. Fine specimens, in the collection of the Geologic^,! Survey of Canada, show dis- 38 THE GEOLOGICAL HISTORY OF PLANTS. tinct evidence of the organic character of the wedge- shaped fronds. It is from the Utica shale, and elsewhere in the Siluro-Cambrian. It is just possible, as suggested by Hall, that this plant may be of higher rank than the Algae. The genus Pdlmophycus of Hall includes a great va- n'ety of uncertain objects, of which only a few are prob- ably true Algae. I have specimens of fragments sJT.ilar to his P. virgatus, which show distinct carbonace«.'u8 films, and others from the Quebec group, which seem to be cylindrical tubes now flattened, and which have con- tained spindle-shaped sporangia of large size. Tortuous and curved flattened stems, or fronds, from the Upper Silurian limestone of Gaspe, also show organic matter. Respecting the forms referred to Licrophycus by Billings, containing stems or semi-cylindrical markings springing from a common base, I have been in great doubt. I have not seen any specimens containing une- quivocal organic matter, and am inclined to think that most of them, if not the whole, are casts of worm-bur- rows, with trails radiating from them. f Though I have confined myself in this notice to plants, or supposed plants, of the Lower Palaeozoic, it may be well to mention the remarkable Cauda-Galli fucoids, re- ferred by Hall to the genus Spirophyton, and which are characteristic of the oldest Erian beds. The specimens which I have seen from New York, from Gasp6, and from Brazil, leave no doubt in my mind that these were really marine plants, and that the form of a spiral frond, assigned to them by Hall, is perfectly correct. They must have been very abundant and very graceful plants of the early Erian, immediately after the close of the Silurian period. We come now to notice certain organisms referred to Algae, and which are either of animal origin, or are of higher grade than the sea-weeds. We have already dis- LAURENTIAN AND EARLY PALEOZOIC. 39 cussed the questions relating to Prototaxites. Drepano- phycus, of Goeppert,* I suspect, is only a badly preserved branch or stem of the Erian land-plant known as Arthro- stigma. In like manner, Haliserites Dechenianus,\ of Goeppert, is evidently the land-plant known as Psilophy- ton. Sphcerococcites dentatus and *S^. serra — the Fucoides dentatus and serra of Brongniart, from Quebec — are graptolites of two species quite common there. J Dic- tyopliyton and Uphantenia, as described by Hall and the author, are now known to be sponges. They have be- come DictyospongicB. The curious and very ancient fos- sils referred by Forbes to the genus Oldhamia are perhaps still subject to doubt, but are usually regarded as Zo- ophytes, though it is quite possible they may be plants. Though I have not seen the specimens, I have no doubt whatever that the plants, or the greater part of them, from the Silurian of Bohemia, described by Stur as Algae and Characeae,* are really land-plants, some of them of the genus Psilophyton. I may say in this connection that specimens of flattened Psilophyton and Arthrostig- ma, in the Upper Silurian and Erian of Gaspe, would probably have been referred to Algge, but for the fact that in some of them the axis of barred vessels is preserved. It is not surprising that great difficulties have occurred in the determination of fossil Algae. Enough, however, remains certain to prove that the old Cambrian and Silu- r.an seas were tenanted with sea-weeds not very dissimilar from those of the present time. Ic is further probable that some of the graphitic, carbonaceous, a-nd bituminous * "Fossile Flora," 1852, p. 92, Table xli. f Ibid., p. 88, Table ii. X Brongniart, " Vegeteaux Fossiles," Plate vi., Figs. 7 to 12. * " Proceedings of the Vienna Academy," 1881. Hostinella, of this author, is almost certainly Psilophyton, and his Barrandiana seems to in- clude Arlhrostigma, and perhaps leafy branches of Berwynia. These curious plants should be re-examined. 40 THE GEOLOGICAL HISTORY OF PLANTS. i ;i U 4 shales and limestones of the Silurian owe their carbona- ceous matters to the decomposition of Algse, though pos- sibly some of it may have been derived from Graptolites and other corneous Zoophytes. In any case, such micro- .;)6 Fio. 14. — Silurian vegetation restored. Protaiviularia^ Bertri/nia, Kema- tophyton^ iiphenophyllum^ Arthrostiyma, Bnlophyton. scopic examinations of these shales as I have made, have not produced any evidence of the existence of plants of higher grade, while those of the Erian and Carboniferous periocs, similar to the naked eye, abound in such evi- dence. It is also to be observed that, on the surfaces of ■( r/^/»/«IA/VI/V/,^« LAURENTIAN AND EA.^LY PALAEOZOIC. 41 beds of sandstone in the Upper Cambrian, carbonaceous debris, which seems to be the remains of either aquatic or land plants, is locally not infrequent. Referring to the land vegetation of the older rocks, it is difficult to picture its nature and appearance. We may imagine the shallow waters filled with aquatic or am- phibious Rhizocarpean plants, vast meadows or brakes of the delicate Psilophyton and the starry Protannularia and some tall trees, perhaps looking like gigantic club- mosses, or possibly with broad, flabby leaves, mostly cellu- lar in texture, and resembling Algae transferred to the air. Imagination can, however, scarcely realise this strange and grotesque vegetation, which, though possibly copious . and luxuriant, must have been simple and monotonous iji^ aspect, and, though it must have produced spores and seeds and even fruits, these were probably all of the types seen in the modern acrogens and gymnosperms. " In garments green, indistinct in the twilight, They stand like Druids of old, with voices sad and prophetic." Prophetic they truly were, as we shall find, of the more varied forests of succeeding times, and they may also help us to realise the aspect of that still older vege- tation, which is fossilised in the Laurentian graphite ; though it is not impossible that this last may have been of higher and more varied types, and that the Cambrian and Silurian may have been times of depression in the vegeta- ble world, as they certainly were in the submergence of much of the land. These primeval woods served at least to clothe the nakedness of the new-born land, and they may have shel- tered and nourished forms of land-life still unknown to us, as we find as yet only a few insects and scorpions in the Silurian. Tiiey possibly also served to abstract from the atmosphere some portion of its superabundant car- bonic acid harmful to animal life, and they stored up 42 TJIE GEOLOGICAL HISTORY OF PLANTS. supplies of graphite, of petroleum, and of illuminating gas, useful to man at the present day. We may write of them and draw their forms with the carbon which they themselves supplied. i I < t>4 ; I i . ^ NOTE TO CHAPTER XL Examination of Prototaxites {Nematopliyton), by Prof. Pen- hallow, OF McGiLL University. Prof. Penhallow, having kindly consented to re-examine my specimens, has furnished me with elaborate notes of his facts and conclusions, of which the following is a summary, but which it is hoped will be published in full : " 1. Concentric Layers. — The inner face of each of these is com- posed of relatively large tubes, having diameters from 13'6 to 34"6 micro-millimetres. The outer face has tubes ranging from 13'8 to 27"6 mm. The average diameter in the lower surface approaches to 34, that in the outer to 13-8. There is, however, no abrupt termination to the surface of the layers, though in some specimens they separate easily, with shining surfaces. "3. Minute Structure. — In longitudinal sections the principal part of the structure consists of longitudinal tubes of indeterminate length, and round in cross-section. They are approximately parallel, but in some cases may be seen to bend sinuously, and are not in direct contact. Finer myceloid tubes, 5'33 mm. in diameter, trav- erse the structure in all directions, and are believed to branch off from the larger tubes. In a small specimen supposed to be a branch or small stem, and in which the vertical tubes are somewhat distant from one another, this horizontal system is very largely developed; but is less manifest in the older stems. The tubes themselves show no structure. The ray-like openings in the substance of the tissue are evidently original parts of the structure, but not of the nature of medullary rays. They are radiating spaces running outward in an interrupted manner or so tortuously that they appear to be inter- rupted in their course from the centre towards the surface. They show tubes turnmg into them, branching into them, and approxi- mately horizontal, but tortuous. On the external surface of some specimens these radial spaces are represented by minute pits irregu- ^...r.n,.^.uunr^m LALTvENTIAN AND EARLY PALEOZOIC. 48 larly or spirally arranged. The transverse swellings of the stem show no difference of structure, except that the tubes or cells may be a little more tortuous, and a transverse film of coaly matter extends from the outer coaly envelope inwardly. This may perhaps be caused by some accident of preservation. The outer coaly layer shows tubes similar to those of the stem.* The horizontal or oblique flexures of the large tubes seem to be mainly in the vicinity of the radial openings, and it is in entering these that they have been seen to branch." The conclusions arrived at by Prof. Penhallow are as follows : " 1. The plant was not truly exogenous, and the appearance of rings is independent of the causes which determine the layers of growth in exogenous plants. " 2. The plant was possessed of no true bark. Whatever cortical layer was present was in all probability a modification of the general structure, f "3. An intimate relation exists between the large tubular cells and the myceloid filaments, the latter being a system of small branches from the former ; the branching being determined chiefly in certain special openings which simulate medullary rays. " 4. The specimens examined exhibit no evidence of special de- cay, and the structure throughout is of a normal character. " 5. The primary structure consists of large tubular ce)ls without apparent terminations, and devoid of structural markings, with which is associated a secondary structure of myceloid filaments aris- ing from the former. " 6. The structure of Nematophyton as a whole is unique ; at least there is no plant of modern type with which it is comparable. Nevertheless, the loose character of the entire structure ; the inter- minable cells; their interlacing; and, finally, their branching into a secondary series of smaller filaments, point with considerable force to the true relationship of the stem as being with Algae or other Thallo- phytes rather than with Gymnosperms. A more recent examination * It is possible that these tubes may be merely part of the stem at- tached to the bark, which seems to me to indicate the same dense cellular structure seen in the bark of Lepidodc7idra, etc. f On these points I would reserve the considerations ; 1. That there must have been some relation between the mode of growth of these great stems and their concentric rings ; and, 2. That the evidence of a bark is as strong as in the case of any Palaeozoic tree in which the bark is, aa usual, carbonised. • wf 44 THE GEOLOGICAL HISTORY OF PLANTS. of a laminated resinous substance found associated with the plant shows that it is wholly amorphous, and, as indicated by distinct lines of flow, that it must have been in a plastic state at a former period. The only evidence of structure was found in certain well-deflned mycelia, which may have been derived from associated vegetable matter upon which they were growing, and over which the plastic matrix flowed." 1 have only to add to this description that when we consider that Nematophyton Logani was a large tree, sometimes attaining a diam- eter of more than two feet, and a stature of at least twenty before branching ; that it had great roots, and gave off large branches ; that it was an aerial plant, probably flourishing in the same swampy flats with Psilophyton, Arthrostigtna, and Leptophleum ; that the peculiar bodies known as Pachytheca were not unlikely its fruit — we have evidence that there were, in the early Palaeozoic period, plants scarcely dreamt of by modern botany. Only when the appendages of these plants are more fully known can we hope to understand them. In the mean time, I may state that there were probably differ- ent species of these trees, indicated more particularly by the stems I have described as Nematoxylon and Celluloxylon.* There were, I think, some indications that the plants described by Carruthers as Berwynia, may also be found to have been generically the same. The resinous matter mentioned by Prof. Penhallow is found in great abundance in the beds containing Nem. *ophyton, and must, I think, have been an exudation from its bark. * "Journal Geol. Society of London," 1863, 1881. CHAPTER III. THE ERIAN OR DEVONIAN FORESTS — ORIGIN OF PETRO- LEUM— THE AGE OF ACROGENS AND GYMNOSPERMS. In the last chapter we were occupied with the com- paratively few and obscure remains of plants entombed in the oldest geological formations. We now ascend to a higher plane, that of the Erian or Devonian period, in which, for the first time, we find varied and widely dis- tributed, forests. The growth of knowledge with respect to this flora has been somewhat rapid, and it may be interesting to note its principal stages, as an encouragement to the hope that we may yet learn something more satisfactory re- specting the older floras we have just discussed. In Goeppert's memoir on the flora of the Silurian, Devonian, and Lower Carboniferous rocks, published in I860,* he enumerates twenty species as Silurian, but these are all admitted to be Algae, and several of them are re- mains which mnv be fairly claimed by the zoologists as zoophytes, or tr s of worms and mollusks. In the Lower Devonian he knows but six species, five of which are Algae, and. the remaining one a Sif/illaria, but this is of very doubtful nature. In the Middle Devonian he gives but one species, a land-plant of the genus Lepidodcndron. In the Upper Devonian the number rises to fifty-seven, of which all but seven are terrestrial plants, representing * Jena, 1860. ' 1 . .1 Pt- - j W ' p 1 W- r ■' j : 1 :» ! ; ! r .,- i r 46 THE GEOLOGICAL UISTORY OF PLANTS. a large number of the genera occurring in the succeeding Carboniferous system. Goeppert does not inchide in his enumeration the plants from the Devonian of Gaspe, described by the author in 1859,* having seen only an abstract of the paper at the time of writing his memoir, nor does he appear to have any knowledge of the plants of this age described by Lcsquereux in Rogers's ** Pennsylvania." These might have added ten or twelve species to his list, some of them probably from the Lower Devonian. It is further to be observed that a few additional species had also been recognised by Peach in the Old Red Sandstone of Scotland. But fiom 1860 to the present time a rich harvest of specimens has been gathered from the Gaspe sandstones, from the shales of southern New Brunswick, from the sandstones of Perry in Maine, and from the wide-spread Erian areas of New York, Pennsylvania, and Ohio. Nearly all tiiese specimens have passed through my hands, and I am now able to catalogue about a hun- dred species, representing more than thirty genera, and including all the great types of vascular Cryptogams, the Gymnosperms, and even one (still doubtful) Angiosperm. Many new forms have also been described from the De- vonian of Scotland and of the Continent of Europe. Before describing these plants in detail, we may refer to North America for illustration of the physical condi- tions of the time. In a physical point of view the north- ern hemisphere presented a great change in the Erian period. There were vast foldings of the crust of the earth, and great emissions of volcanic rock on both sides of the Atlantic. In North America, while at one time the whole interior area of the continent, as far north as * " Journal of the Geological Society of London," also " Canadian Naturalist." THE BRIAN OR DEVONIAN FORESTS. 47 the Great Lakes, was occupied by a vast inland sea, studded with coral islands, the long Appalachian ridge had begun to assume, along with the old Laurentian land, something of the form of our present continent, and on the margins of this Appalachian belt there were wide, swampy flats and shallow-Avater areas, which, under the mild climate that seems to have characterised this period, were admirably suited to nounsh a luxuriant vegetation. Under this mild climate, also, it would seem that new forms of plants were first introduced in the far north, where the long continuance of summer sunlight, along with great warmth, seems to have aided in their introduction and early ex- tension, and thence made their way to the southward, a process which, as Gray and others have shown, has also occurred in later geological times. The America of this Erian age consisted during the greater part of the period of a more or less extensive belt of land in the north with two long tongues descending from it, one along the Appalachian line in the east, the other in the region west of the Rocky Mountains. On the seaward sides of these there were low lands covered witli vegetation, while on the inland side the great in- terior sea, with its verdant and wooded islands, realised, though probably with shallower water, the conditions of the modern archipelagoes of the Pacific. Europe presented conditions somewhat similar, having in the earlier and middle portions of the period great sea areas with insular patches of land, and later wide tracts of shallow and in part enclosed water areas, swarming with fishes, and having an abundant vegetation on their shores. These were the conditions of the Eifel and Devonshire limestones, and of the Old Red Sandstone of Scotland, and the Kiltorcan beds of Ireland. In Europe also, as in America, there were in the Eriim age great ejections of igneous rock. On both sides of the Atlantic there were somewhat varied and changing conditions of I ii 48 THE GEOLOGICAL HISTORY OF PLANTS. (I land and water, and a mild and equable climate, permit- ting the existence of a rich vegetation in high northern latitudes. Of this latter fact a remarkable example is afforded by the beds holding plants of this age in Spitz- bergen and Bear Island, in its vicinity. Here there seem to be two series of plant-bearing strata, one with the vegetation of the Upper Erian, the other with that of the Lower Carboniferous, though both have been united by Heer under his so-called "Ursa Stage," in which he has grouped the characteristic plants of two distinct periods. This has recently been fully established by the researches of Nathorst, though the author had already suggested it as the probable explanation of the strange union of species in the Ursa group of Heer. In studying the vegetation of this remarkable period, we must take merely some of the more important forms as examples, since it would be impossible to notice all the species, and some of them may be better treated in the Carboniferous, where they have their headquarters. (Fig. 15.) I may first refer to a family which seems to have cul- minated in the Erian age, and ever since to have occupied a less important place. It is that of the curious aquatic plants known as Rhizocarps,* and referred to in the last chapter. My attention was first directed to these organisms by the late Sir W. E. Logan in 18G9. He had obtained from the Upper Erian shale of Kettle Point, Lake Huron, specimens filled with minute circular discs, to which he referred, in his report of 1863, as "microscopic orbicular bodies." Recognising them to be macrospores, or spore- cases, I introduced them into the report on the Erian * Or, as they have recently been named by some botanists, "Ilete- rosporous Filices," though they are certainly not ferns in any ordinary sense of that term. I ill 1 THE BRIAN OR DEVONIAN FORESTS. 49 flora, which I was then preparing, and which was pub- lished in 1871, under the name Sporangites Huronensis. In 1871, having occasion to write a communication to the "American Journal of Science" on the question then FiQ. 15. — Vegetation of the Devonian period, restored. Catamites, I^lo- phi/ton, Zepiophleum, Zeptdodendron, Vordaites, SitjiUaria, Dadoxy- loUy Aster oph'jllites, PlatypJiijUum. raised as to the sliare of spores and spore-cases in the ac- cumulation of coal, a question to be discussed in a sub- f! I i \ *:t i I 60 THE GEOLOGICAL HISTORY OF PLANTS. sequent chapter, these curious little bodies were again reviewed, and were described in substance as follows : '* The oldest bed of spore-cases known to me is that at Kettle Point, Lake Huron. It is a bed of brown bituminous shale, burning with much flame, and under a lens is seen to be studded with flattened disc-like bodies, scarcely more than a hundredth of an inch in diameter, which under the microscope are found to be spore-cases (or macrospores) slightly papillate externally (or more properly marked with dark pores), and sometimes show- ing a point of attachment on one side and a slit more or less elongated and gaping on the other. When slices of the rock are made, its substance is seen to be filled with these bodies, which, viewed as transparent objects, appear yellow like amber, and show little structure, except that the walls can be distinguished from the internal cavity, which may sometimes be seen to enclose patches of granu- lar matter. In the shale containing them are also vast numbers of rounded, translucent granules, which may be escaped spores (microspores)." The bed containing these spores at Kettle Point was stated, in the reports of the "Geological Survey of Canada," to be twelve or fourteen feet in thickness, and besides these specimens it contained fossil plants referable to the species Calamites inornatus and Lepidodendro7i primcevum, and I not unnaturally supposed that the Sporangites might be the fruit of tlie latter plant. I also noticed their resemblance to the spore-cases of L. corrugotum of the Lower Carboniferous (a Lepidodendron allied to L. primwvum), and to those from Brazil described by Carruthers under the name Flemingitcs, as well as to those described by Huxley from certain English coals, and to those of the Tasmanite or white coal of Australia. The bed at Kettle Point is shown to be marine by its holding the sea-weed known as Spirophi/ion, and shells of Linyula. The subject did not again come under my notice till THE BRIAN OR DEVONIAN FORESTS. 61 1883, when Prof. Orton, of Columbus, Ohio, sent me some specimens from the Erian shales of that State, wiiich on comparison seemed undistinguishable from Sporangites Huronensis.* Prof. Orton read an interest- ing paper on these bodies, at the meeting of the American Association in Montreal, in which were some new and striking facts. One of these was the occurrence of such bodies throughout the black shales of Ohio, extending **from the Huron River, on the shore of Lake Erie, to the mouth of the Scioto, in the Ohio Valley, with an extent varying from ten to twenty miles in breadth," and estimated to be three hundred and fifty feet in thickness. I have since been informed by my friend Mr. Thomas, of Chicago, that its thickness, in some places at least, must be three times that amount. About the same time, Prof. Williams, of Cornell, and Prof. Clarke, of Northampton, announced similar discoveries in the State of New York, so that it would appear that beds of vast area and of great thickness are replete with these little vegetable discs, usu- ally converted into a highly bituminous, amber-like sub- stance, giving a more or less inflammable character to the containing rock. Another fact insisted on by Prof. Orton was the ab- sence of Le])idodendroid cones, and the occurrence of filamentous vegetable matter, to which the Sporangites seemed to be in some cases attached in groups. Prof. Orton also noticed the absence of the trigonal form, which belongs to the spores of many Lepidodendra, though this is not a constant character. In the discussion on Prof. Orton's paper, I admitted that the facts detailed by him shook my previous belief of the lycopodiaceous character * These shales have been described, as to their chemical and geological relations, by Dr. T. Sterry Hunt, "American Journal of Science," 1803, and by Dr. Newberry, in the " Reports of the Geological Survey of Ohio," vol. i., 1863, and vol. iii., 1878. "TT 62 THE GEOLOGICAL HISTORY OF PLANTS. ' P I t ti: ft t of these bodies, and induced me to suspect, with Prof. Orton, that they might have belonged to some group of aquatic plants lower than the Lycopods. Since the publication of my paper on Rhizocarps in the PalaBOzoic period above referred to, I have received two papers from Mr. Edward Wethered, F. G. S., in one of which he describes spores of plants found in the lower limestone shales of the Forest of Dean, and in the other discusses more generally the structure and origin of Car- boniferous coal-beds.* In both papers he refers to the occurrence in these coals and shales of organisms essen- tially similar to the Brian spores. In the "Bulletin of the Chicago Academy of Science," January, 1884, Dr. Johnson and Mr. Thomas, in their paper on the ** Microscopic Organisms of the Boulder Clay of Chicago and Vicinity," notice Sporangites Huronensis as among these organisms, and have discovered them also in large numbers in the precipitate from Chicago city water-supply. They refer them to the decomposition of the Brian shaies, of which boulders filled with these or- ganisms are of frequent occurrence in the Chicago clays. The Sporangites and their accompaniments in the boulder clay are noticed in a paper by Dr. G. M. Dawson, in the "Bulletin of the Chicago Academy," June, 1885. Prof. Clarke has also described, in the "American Journal of Science" for April, 1885, the forms already alluded to, and v/hich he finds to consist of microspores enclosed in sporocarps. He compares these with my Spora7igites Huronensis and Protosalvinia bilohata, but I think it is likely that one of them at least is a distinct species. I may add that in the "Geological Magazine" for 1875, Mr. Newton, F. G. S., of the Geological Survey of * " Cotteswold Naturalists' Field Club," 1884; "Journal of the Royal Microscopic ' Society," 1885. '■S THE ERLVN OR DEVONIAN FORESTS. 53 » England, published a description of the Tasmanite and Australian white coal, in which he shows that the or- ganisms in these deposits are similar to my Sporangites Huronensis, and to the macrospores previously described by Prof. Huxley, from the Better-bed coal. Mr. Newton does not seem to have been aware of my previous descrip- tion of Sporangites, and proposes the name Tasmanites punctatus for the Australian form. Here we have the remarkable fact that the waste macrospores, or larger spores of a species of Cryptoga- mous plant, occur dispersed in countless millions of tons through the shales of the Erian in Canaaa and the United States. No certain clue seemed to be afforded by all these observations as to the precise affinities of these widely distributed bodies ; but this was furnished shortly after from an unexpected quarter. In March, 1883, Mr. Or- ville Derby, of the Geological Survey of Brazil, sent me specimens found in the Erian of that country, which seemed to throw a new light on the whole subject. These I described and pointed out their connection with Sporan- gites at the meeting of the American Association at Min- neapolis, in 1883, and subsequently published my notes respecting them in its proceedings, and in the ''Canadian Record of Science." Mr. Derby's specimens contained the curious «^piral sea-weed known as Spiropliyton, and also minute rounded Sporangites like those obtained in the Erian of Ohio, and of which specimens had been sent to me some years be- fore by tlie late Prof. Hartt. But they differed in show- ing tlie remarkable fact tliat these rounded bodies are enclosed in considerable numbers in spherical and oval sacs, the walls of Avhicli are composed of a tissue of hexagonal cells, and which resemble in every respect the involucres or spore-sacs of the little group of modern acrogens known as Rhizocarps, and living in shallow 64 THE GEOLOGICAL HISTORY OF PLANTS. water. More especially they resemble the sporocarps of the genus Salvinia. This fact opened up an entirely new field of investigation, and I at once proceeded to compare the specimens with the fructification of modern Rhizocarps, and found that substantially these multitu- dinous spores embedded in the Erie shales may be re- garded as perfectly analogous to the larger spores of the modern Salvinia natans of Europe, as may be seen by the representation of them in Fig. 16. ® AX yix DX Fig. 16. — Sporangites {I^otoaahinia). a. Sporangites Brasiliends, natural Bize. AX, Same, magnified, b, Sp. biloba, natural size, c, Detached umerosporos. n, Spore-cases of 5fl«'»«trt iiatans. dx. Same, magnitied. E, Shale with sporangites, vertical section, highly magnified. Ill The typical macrospores from the Erian shales are perfectly circular in outline, and in the flattened state ap- pear as discs with rounded edges, their ordinary diameter being from one seventy-fifth to one one hundredth of an inch, though they vary considerably in size. This, how- ever, I do not regard as an essential character. The edges, as seen in profile, are smooth, but the flat surface often presents minute dark spots, which at first I mis- THE ERIAN OR DEVONIAN FORESTS, 65 took for papillse, but now agree with Mr. Thomas in rec- ognising them as minute prres traversing the wall of the disc, and similar to those which Mr. Newton has described in Tasmanite, and which Mr. Wethered has also recog- nised in the similar spores of the Forest of Dean shales. The walls also sometimes show faint indications of con- centric lamination, as if they had been thickened by suc- cessive deposits. As seen by transmitted light, and either in front or in profile, the discs are of a rich amber colour, translucent and structureless, except the pores above referred to. The wails are somewhat thick, or from one-tenth to one- twentieth the diameter of the disc in thickness. They never exhibit the triradiate marking seen in spores of Ly- copods, nor any definite point of attachment, though they sometimes show a minute elongated spot which may be of this nature, and they are occasionally seen to have opened by slits on the edge or front, where there would seem to have been a natural line of dehiscence. The in- terior is usually quite vacant or structureless, but in some caries there are curved internal markings which may indi- cate a shrunken lining memorane, or the remains of a prothallus or embryo. Occasionally a fine granular sub- stance appears in the interior, possibly remains of mi- crospores. The discs are usually detached and destitute of any envelope, but fragments of flocculent cellular matter are associated with them, and in one specimen from the cor- niferous limestone of Ohio, in Mr. Thomas's collection, I have found a group of eight or more discs partly enclosed in a cellular sac-like membrane of similar character to that enclosing the Brazilian specimens already referred to. The characters of all the specimens are essentially similar, and there is a remarkable absence of other organ- isms in the shale. In one instance only, I have observed a somewhat smaller round body with a dark centre or 56 THE GEOLOGICAL HISTORY OF PLANTS. 1 " ' nucleus, and a wide translucent margin, marked by a slight granulation. Even this, however, may indicate nothing more than a different state of preservation. It is proper to observe here that the wall or enclosing sac of these macrospores must have been of very dense consistency, and now appears as a highly bituminous sub- stance, in this agreeing with that of the spores of Lyco- pods, and, like them, having been when recent of a highly carbonaceous and hydrogenous quality, very combustible and readily admitting of change into bituminous matter. In the paper already referred to, on spore-cases in coals, I have noticed that the relative composition of lyco- podium and cellulose is as follows : Cellulose, CgiHgoOgo* Lycopodium, C43H19.NO5-. Thus, such spores are admirably suited for the pro- duction of highly carbonaceous or bituminous coals, etc. Nothing is more remarkable in connection with these bodies than their uniformity of structure and form over so great areas and throughout so great thickness of rock, and the absence of any other kind of spore-case. This is more especially noteworthy in contrast with the coarse coals and bituminous shales of the Carboniferous, which usually contain a great variety of spores and sporangia, indicating the presence of many species of acrogenous plants, while the Erian shales, on the contrary, indicate the almost exclusive predominance of one form. This con- trast is well seen in the Bedford shales overlying these beds, and I believe Lower Carboniferous.* Specimens of these have been kindly communicated to me by Prof. Orton, and have been prepared by Mr. Thomas. In these we see the familiar Carboniferous spores with triradiate markings called Triletes by Reinsch, and which are simi- lar to those of Lycopodiaceous plants. Still more abun- * According to Newberry, lower part of Waverly group. IL THE BRIAN OR DEVONIAN FORESTS. 57 id by a indicate m. nclosing ry dense lous sub- )f Lyco- a highly ibustible i matter, in coals, of lyco- the pro- •als, etc. ith these orni over of rock, ie. This he coarse is, which Dorangia, rogenous licate the ^his con- ng these 3imens of by Prof. In these triradiate are simi- ore abun- up. dant are those spinous and hooked spores or sporangia, to which the names Sporocarpon, Zygosporites, and Tra- quaria have been given, and some of which Williamson has shown to be spores of Lycopodiaceous plants.* The true ''Sporangites," on the contrary, are round and smooth, with thick bituminous walls, which are punctured with minute transverse pores. In these re- spects, as already stated, they closely resemble the bodies found in the Australian white coal and Tasmanite. The precise geological age of this last material is not known with certainty, but it is believed to be Palaeozoic. With reference to the mode of occurrence of these bodies, we may note first their great abundance and wide distribution. The horizontal range of the bed at Kettle Point is not certainly known, but it is merely a northern outlier of the great belt of Erian shales referred to by Prof. Ortou, and which extends, with a breadth of ten to twenty miles, and of great thickness, across the State of Ohio, for nearly two hundred miles. This Ohio black shale, which lies at the top of the Erian or the base of the Carboniferous, though probably mainly of Erian age, appears to abound throughout in these organisms, and in some beds to be replete with them. In like manner, in Brazil, according to Mr. Derby, these organisms are dis- tributed over a wide area and throughout a great thick- ness of shale holding Spirophyton, and apparently belong- ing to the Upper Erian. The recurrence of similar forms in the Tasmanite and white coal of Tasmania and Aus- tralia is another important fact of distribution. To this * Traquaria is to be distinguished from the calcareous bodies found in the corniferous limestone of Kelly's Island, which I have described in the " Canadian Naturalist " as Saccamina Eriana, and believe to be Fo- raminiferal tests. They have since been described by Ulrich under a different name {Mallerina: contribution to "American Palaeontology," 1886). Sec Dr. Williamson's papers in "Transactions of Royal Society of London." ff8 THE GEOLOGICAL HISTORY OF PLANTS. we may add the appearance of these macrospores in coals and shales of the Carboniferous period, tliough there in association with other forms. It is also to be observed that the Erian shales, and the Forest of Dean beds described by Wethered, are marine, as shown by their contained fossils ; and, though I have no certain information as to the Tasmanite and Austra- lian white coal, they would seem, from the description of Milligan, to occur in distinctly aqueous, possibly estua- rine, deposits. Wethered has shown that the discs de- scribed by Huxley and Newton in the Better-bed coal occur in the earthy or fragmentary layers, as distin- guished from the pure coal. Those occurring in cannel coal are in the same case, so that the general mode of occurrence implies water-driftage, since, in the case of bodies so large and dense, wind-driftage to great distances would be impossible. These facts, taken in connection with the differences between these macrospores and those of any known land- plant of the Palaeozoic, would lead to the inference that they belonged to aquatic plants, and these vastly abundant in the waters of the Erian and Carboniferous periods. It is still further to be observed that they are not, in the Erian beds, accompanied with any remains of woody or scalariform tissues, such as might be expected in con- nection with the debris of terrestrial acrogens, and that, on the other hand, we find them enclosed in cellular sporocarps, though in the majority of cases these liave been removed by dehiscence or decay. These considerations, I think, all point to the prob- ability which I have suggested in my ])apers on this sub- ject referred to above, that we have in these objects the organs of fructification of plants belonging to the order Bhizocarpece, or akin to it. The comparisons which I have instituted with the sporocarps and macrospores of these plants confirm this suggestion. Of the modern THE BRIAN OR DEVONIAN FORESTS. 69 Bpecies which I have had an opportunity to examine, Salvinia natans of Europe perhaps presents the closest resemblance. In this plant groups of round cellular sporocarps appear at the bascv of the floating fronds. They are about a line in diameter when mature, and are of two kinds, one containing macrosporcs, the other mi- crospores or antheridia. The first, when mature, hold a number of closely packed globular or oval sporangia of loose cellular tissue, attached to a central placenta. Each of these sporangia contains a single macrospore, perfectly globular and smooth, with a dense outer membrane (ex- hibiting traces of lamination, and showing within an irregularly vacuolated or cellular structure, probably a prothallus). I cannot detect in it the peculiar pores which appear in the fossil specimens. Each macrospore is about one-seventieth of an inch in diameter when ma- ture. The sporocarps of the microspores contain a vastly greater number of minute sporangia, about one two-hun- dredths of an inch in diameter. These contain disc-like antheridia, or microspores of very minute size. The discs from Kettle Point and from the Ohio black shale, and from the shale boulders of the Chicago clays, are similar to the macrospores of Salvinia, except that they have a thicker wall and are a little less in diameter, being about one-eightieth of an inch. The Brazilian sporocarps are considerably larger than those of the mod- ern Salvinia, and the macrospores approach in size to those of the modern species, being one seventy-fifth of an inch in diameter. They also seem, like the modern spe- cies, to have thinner walls than those from Canada, Ohio, and Chicago. No distinct indication has been observed in the fossil species of the inner Sporangium of Salvinia. Possibly it was altogether absent, but more probably it is not preserved as a distinct structure. With reference to the microspores of Salvinia, it is to be observed that the sporocarps, and the contained spores li Mil ^^ 1 i ; 11 Lt- 60 THE GEOLOGICAL HISTORY OF PLANTS. or antheridia, aro very delicate and destitute of the dense outer wall of the macrospores. Hence such parts are little likely to have been preserved in a fossil state ; and in the Erian shales, if present, they probably appear merely as flocculcnt carbonaceous matter not distinctly marked, or as minute granules not well defined, of which there arc great quantities in some of the shales. The vegetation appertaining to the Sporangites has not been distinctly recognised. I have, however, found in one of the Brazilian specimens two sporocarps attached to what seems a fragment of a cellular frond, and numer- ous specimens of the supposed Alga), named Sjnrophyloriy are found in the shales, but there is no evidence of any connection of this plant with the Protosalvinia. Modern Rhizocarps present considerable differences as to their vegetative parts. Some, like Pilularia, have simple linear leaves ; others, like Marsilea, have leaves in whorls, and cuneate in form ; while others, like Azolla and Salvinia, have frondose leaves, more or less pinnate in their arrangement. If we inquire as to fossils repre- senting these forms of vegetation, we shall find that some of the plants to be noticed in the immediate sequel may have been nearly allied to the Rhizocarps. In the mean time 1 may state that I have proposed the generic name Protosalvinia for these curious macrospores and their coverings, and have described in the paper in the " Bul- letin of the Chicago Academy of Sciences," already quoted, five species which may be referred to this genus. These facts lead to inquiries as to the origin of the bituminous matter which naturally escapes from the rocks of the earth as petroleum and inflammable gas, or which may be obtained from certain shales in these forms by distillation. These products are compounds of carbon and hydrogen, and may be procured from recent vegetable substances by destructive distillation. Some vegetable matters, also, are much richer in carbon and hydrogen THE BRIAN OR DEVONIAN FORESTS. 61 or than others, and it is a remarkable fact that the spores of certain cryptogamous plants are of this kind, as wo see iu the inflammable character of the dry spores of Lycopo- dium ; and we know that the slow putrefaction of such material undergrr and effects chemical changes by which bituminous matter can be produced. There is, there- fore, nothing unreasonable in the supposition advanced by Prof. Orton, that the spores so abundantly contained in the Ohio black shales are important or principal sources of the bituminous matter which they contain. Micro- scopic sections of this shale show that much of its mate- rial consists of the rich bituminous matter of these spores (Fig. 16). At the same time, while we may trace the bitumen of these shales, and of some beds of coal, to this cause, we must bear in mind that there are other kinds of bituminous rocks which show no such structures, and may have derived their combustible material from other kinds of vegetable matter, whether of marine or of land plants. We shall better understand this when we have considered the origin of coal. The macrosporcs above referred to may have belonged to humble aquatic plants mantling the surfaces of water or growing up from the bottom, and presenting little aerial vegetation. But there are other Erian plants, as already mentioned, which, while of higher structure, may be of Rhizocarpean affinities. One of these is the beautiful plant with whorls of wedge-shaped leaves, to which the name Sphenophyllum (see Fig. 20) has been given. Plants referred to this genus have been described by Lesquereux from the upper part of the Siluro-Cambrian,* and a beautiful little spe- cies occurs iu the Erian shales of St. John, New Bruns- wick.f The genus is also continued, and is still more * " American Journal of Science." f Dawson, " Report on Devonian Plants," 1870. 62 THE GEOLOGICAL HISTORY OF PLANTS. abundant, in tlio Carboniferous. Many years ago I ob- served, in a beautiful specimen collected by Sir W. E. Logan, in New Brunswick, tliat the stem of this plant had an axis of reticulated and scalariforra vessels, and an outer bark.* Renault and Williamson have more recently obtained more perfect specimens, and the former has figured a remarkably complex triangular axis, containing punctate and barred vessels, and larger punctate vessels filling in its angles. Outside of this there is a cellular inner bark, and this is surrounded by a thick fibrous en- velope. That a structure so complex should belong to a plant so humble in its aflBnities is one of the strange anomalies presented by the old world, and of which we shall find many similar instances. The fruit of Spheno- phyllum was borne in spikes, with little whorls of bracts or rudimentary leaves bearing round sporocarps. Fio. 17. — I^tilophijton jtiumoaum (Lower Carboniferous, Nova Scotia). ^Natural size and muguiiied. A second type of plant, which may have been Rhizo- carpean in its affinities, is that to which I have given the name Ptilopliyton.\ It consists of beautiful feathery * "Journal of the Geological Society," 1865. f Flumalina of Hall. ifi THE ERIAN PR DEVONIAN FORESTS. 08 fronds, apparently bearing on parts of tho main stem or petiole small rounded sporocarps. They are found abun- dantly in tho Middle Erian of tho State of New York, and also occur in Scotland, while one species api)ears to occur in Nova Scotia, as high as the Lower Carboniferous (Figs. 17, 18). These organisms have been variously referred to Lyco- pods, to Alga3, or to Zoophytes, but an extended compari- Fio. 18. — Ptilophyfon TJiomaoni (Scotland), a, Iinprossion of plant in vernation, o, Branches conjecturuliy restored, c, Bruuches of Zyco- podites Miller i, on same slab. son of American and Scottish specimens has led me to the belief that they were aquatic plants, more likely to have been allied to Rhizocarps than to any other group. Some evidence of this will be given in a note appended to this chapter. Ill fr^ >iii I m i f r i 64 THE GEOLOGICAL HISTORY OF PLANTS. 4 ! ill Fio. 19. — I^ilopJiyton, prineeps^ restored (Lower Eriun, Gaspd). o, Fruit, natural sizo. i, Stetn. natunil size, c, Scnlari- fonn tissue of" tlio axis, lii^r.^ily magni- fied. In the restoration, one side is rcpre- Bcatcd in vernation and the other in fruit. Another genus, which I have named Psilophyton * (Figs. 19, 2]), may be re- garded as a connect- ing link between the Rliizocarps and the Lycopods. It is so named from its resem- blance, in some re- spects, to the curi- ous parasitic Lycopods placed in the modern genus Psilotum. Sev- eral species have been described, and they are eminently characteris- tic of the Lower Bri- an, in which they were first discovered in Gasp6. The typ- ical species, Psilophy- ton princeps, which fills many beds of shale and sandstone in Gas- pe Bay and the head of the neighbouring Bay des Chaleurs with its slender stems and creeping, cord-like rhi- zomes, may be thus de- scribed : Stems branching * "Journal of the Geological Society," vola. xv., xviii., and xix., "Re- port on Devonian Plants of Canada," 1871. THE ERIAN OR DEVONIAN FORESTS. 65 Fio. 20. — Sphe- iiophyllum nn- tiguHin (Erian, Is'ew BniiiBwiek), See pp. 61, C7. dichotomously, and covered with interrupted ridges. Leavoo rudimentary, or short, rigid, and pointed ; in barren stems, numerous and spirally arranged • in fertile stems and brauchlets, sparsely scattered or absent ; in decorticated specimens, represented by a minute punctate scars. Young branch- es circinate ; rhizomata cylindrical, cov- ered with hairs or ramenta, and having circular areoles irregularly disposed, giv- ing origin to slender cylindrical rootlets. Internal structure* — an axis of scalari- form vessels, surrounded by a cylinder of parenchymatous cells, and by an outer cylinder of elongated woody cells. Fruc- tilication consisting of naked oval spore- cases, borne usually in pairs on slender, curved pedicels, either lateral or terminal. This species was fully described by me in the papers referred to above, from specimens obtained from the rich exposures at Gaspe Bay, and which enabled me to illus- trate its parts more fully, perhaps, than those of any other species of so great antiquity. In the specimens I had obtained I was able to recognise the forms of the rhizomata, stems, branches, and rudimentary leaves, and also the internal structure of the stems and rhizomata, and to illustrate the remarkable resemblance of tiie forms and structures to those of the modern Psilnlum. The fructification was, however, altogether peculiar, consist- ing of narrowly ovate sporangia, borne usually in pairs, on curvvid and apparently rigid petioles. Under the microscope these sporangia show indications of cellular structure, and appear to have been membranous in char- acter. In some specimens dehiscence appears to have taken place by a slit in one side, and, clay having entered into the interior, both walls of the spore-case can be seen. In other instances, being flattened, they might be m "- r 66 THE GEOLOGICAL HISTORY OF PLANTS. ll f taken for scales. No spores could be observed in any of the specimens, though in some the surface was marked by slight, rounded prominences, possibly the impressions of the spores within. This peculiar and very simple style ;* I Fio. 21. — Lcpidodendron and Psilophyton (Erian, New Bnmswick). A, Lepidodendroii Gaspianuni. b, o, Dsiiophi/ton elegans, of spore-case is also characteristic of other species, and gives to Psilophyton a very distinct generic character. These naked spore-cases may be comj^red to those of such lycopodiaceous plants as Psilotum, in which the 31 III THE BRIAN OB DEVONIAN FORESTS. 67 scales are rudimentary. They also bear some resemblance, though on a much larger scale, to the spore-cases of some Erian ferns {Arclimopteris), to be mentioned in the sequel. On the whole, however, they seem most nearly related to the sporocarps of the Rhizocarpea3. Arthrostigma, which is found in the same beds with Psilophyton, was a plant of more robust growth, with better-developed, narrow, and pointed leaves, borne in a verticillate or spiral manner, and bearing at the ends of its branches spikes of naked sporocarps, apparently simi- lar to those of Psilophyton but more rounded in form. The two genera must nave been nearly related, and the slender branchlets of Arthrostigma are, unless well pre- served, scarcely distinguishable from the stems of Psilo- phyton.* If, now, we compare the vegetation of these and simi- lar ancient plants with that of modern Rhizocarps, we shall find that the latter still present, though in a de- pauperated and diminished fo^-m, some of the character- istics of their predecessors. Some, like Pilularia, have simple linear leaves ; others, like Marsilea, have leaves in verticils and cuneate in form ; while others, like Azolla and Salvinia, have frondose leaves, more or less pinnate in their arrangement. The first type presents little that is characteristic, but there are in the Erian sandstones and shales great quantities of filamentous and linear ob- jects which it has been impossible to refer to any genus, and which might have belonged to plants of the type of Pilularia. It is quite possible, also, that such plants as Psilophyton glabrum and Cordaitcs angustifolia, of which the fructification is quite unknown, may have been allied to Rhizocarps. With regard to the verticillate type, we are at once reminded of Sphenophyllum (Fig. 20), which * Reports of the auther on " Devonian Plants," " Geological Survey cf Canada," which see for details as to Erian Flora of northeaatern America. |l n :t = ill 1 1 i> f I 68 THE GEOLOGICAL HISTORY OF PLANTS. many palseo-botanists have referred to the MarsiUacm, though, like other Palasozoic Acrogens, it presents com- plexities not seen in its modern representatives. S. pri- "ncBVum of Lesquere i? found in the Hudson River group, and my S. antiquum in the Middle Eri.in. Be- sides these, there are in the Silurian and Erian beds plants with verticillate leaves which have been placed with the Annularige, but which may have differed from them in fructification. Annularia laxa, of the Erian, and Protannularia HarJcnessii, of the Siluro-Cambrian, may be given as examples, and must have been aquati«; plants, probably allied to Rhizocarps. It is deserving of notice, also, that the two best-known species of Psilophy- ton {P. princeps and P. rohustius), while allied to Ly- copods by the structure of the stem and such rudimentary foliage as they possess, are also allied, by the form of their fructification, to the Rhizocarps, and not to ferns, as some palaeo-botanists have incorrectly supposed. A similar remark applies to ArthrostUjma ; and the beautiful pinnately leaved Ptilnphyton may be taken to represent that tyi e of foliage as seen in modern Rhizocarps, while the allied forms of the Carboniferous which Lesquereux has named Trochophyllum, seem to have had sporocarps attached to the stem in the manner of Azolla. The whole of this evidence, I think, goes to show that in the Erian period there were vast quantities of aquatic plants, allied to the modern Rhizocarps, and that the so- called Sporangites referred to in this paper were probably the drifted sporocarps and macrospores of some of these plants, or of plants allied to them in structure ard habit, of which the vegetative organs have perished. I have shown that in the Erian period there were vast swampy flats covered with Psilopliyton, and in similar submerged tracts near to the sea the Protosalvinia may have filled the waters and have given off the vast multitudes of macrospores which, drifted by currents, have settled in the THE BRIAN OR DEVONIAN FORESTS. 69 mud of the black shales. "We have thus a remarkable example c? a group of plants reduced in modern times to a few insignificant forms, but which played a great role in the ancient Palaeozoic world. Leaving the Rhizocarps, we may now turn to certain other families of Erian plants. The first to attract our attention in this age would naturally be the Lycopods, the club-mosses or ground-pines, which in Canada and the Eastern States carpet the ground in many parts of our woods, and are so available for the winter decoration of our houses and public buildings. If we fancy one of these humble but graceful plants enlarged to the dimen- Bions of a tree, we shall have an idea of a Lepidodendron, or of any of its allies (Figs. 15, 31). These large lycopo- diaceous trees, which in different specific and generic forms were probably dominant in the Erian woods, re- sembled in general those of modern times in their fruit and foliage, except that their cones were large, and prob- ably in most cases with two kinds of spores, and their leaves were also often very long, thus bearing a due pro- portion to the trees which they clothed. Their thick stems required, however, more strength than is necessary in their diminutive successors, and to meet this want some remarkable structures were introduced similar to those now found only in the stems of i)lants of higher rank. The cells and vessels of all plants consist of thin walls of woody matter, enclosing the sap and other con- tents of these sacs and tubes, and when strength is re- quired it is obtained by lining their interior with suc- cessive coats of the hardest form of woody matter, ii.iually known as lignin. But while the walls remain thin, they afford free passage to the sap to nourish every part. If thickened all over, they would become impervious to sap, and therefore unsuited to one of their most important functions. These two ends of strength and permeability are secured by partial linings of lignin, leaving portions of 8 '■':MlH n, f I 1 I TO THE GEOLOGICAL HISTORY OF PLANTS. the original wall uncovered. But this may be done in a great variety of ways. The most ancient of these contrivances, and one still continued in the world of plants, is that of the barred or scalariform vessel. This may be either square or hex- agonal, so as to admit of being packed without leaving vacancies. It is strengthened by a thick bar of ligneous matter up each angle, and these are connected by cross- bars so as to form a framework resembling several ladders fastened together. Hence the name scalariform, or lad- der-like. Now, in a modern Lycopod there is a central axis of such barred vessels associated with simpler fibres or elongated cells. Even in Sphenopliyllwn and Psilo- pTiyton, already referred to as allied to Rhizocarps,* there is such a central axis, and in the former rigidity is given to this by the vascular and woody elements being ar- ranged in the form of a three-sided prism or three-rayed star. But such arrangements would not suffice for a tree, and hence in the arboreal Lycopods of the Erian age a more complex structure is introduced. The barred ves- sels were expanded in the first instance into a hollow cylinder filled in with pith or cellular tissue, and the outer rind was strengthened with greatly thickened cells. But even this was not sufficient, and in the older stems wedge-shaped bundles of barred tissue were run out from the interior, iorming an external woody cylinder, and in- side of the rind were placed bundles of tough bast fibres. Thus, a stem was constructed having pith, wood, and bark, and capable of additions to the exterior of the woody wedges by a true exogenous growth. The plan is, in short, the same with that of the stems of the exogenous trees of modern times, except that the tissues employed are less complicated. The structures of these remarkable * First noticed by the author, "Journal of Geological Society," 1866; but more completely by Renault, " Comptes Rendus," 1870. THE BRIAN OR DEVONIAN FORESTS. 74 trees, and the manner in which they anticipate those of the true exogens of modern times, have been admirably illustrated by Dr. Williamson, of Manchester. His papers, it is true, refer to these plants as existing in the Carboniferous age, but there is every reason to believe that they were of the same character in the Erian. The plan is the same with that now seen in the stems of exoge- nous phaenogams, and which has long ceased to be used in those of the Lycopods. In this way, however, large and graceful lycopodiaceous trees were constructed in the Erian period, and constituted the staple of its forests. The roots of these trees were equally remarkable with their stems, and so dissimilar to any now existing that botanists were long disposed to regard them as inde- pendent plants rather than roots. They were similar in general structure to the stems to which they belonged, but are remarkable for branching in a very regular man- ner by bifurcation like the stems above, and for the fact that their long, cylindrical rootlets were arranged in a spiral manner and distinctly articulated to the root after the manner of leaves rather than of rootlets, and fitting them for growing in homogeneous mud or vegetable muck They are the so-called Stigmaria roots, which, though found in the Erian and belonging to its lycopo- diaceous plants, attained to far greater importance in the Carboniferous period, where we shall meet with them again. There were different types of lycopodiaceous plants in the Erian. In addition to humble Lycopods like those of our modern woods and great Lepidodendra, which were exaggerated Lycopods, there were thick-stemmed and less graceful species with broad rhombic scars (Leptophleum), and others with the leaf-scars in vertical rows {Sigillaria), and others, again, with rounded leaf-scars, looking like the marks on Stigmaria, and belonging to the genus Cyclostigma. Thus some variety was given to the arbo- real club-mosses of these early forests. (See Fig. 15.) 5>^ 72 THE GEOLOGICAL HISTORY OF PLANTS. Another group of plants which attained to great development in the Erian age is that of the Ferns or Brackens. The oldest of these yet known are found in the Mid- dle Erian. The Eopteris of Sa- porta, from the Silurian, at one time supposed to carry this type much further back, has unfortu- nately been found to be a mere imitative form, consisting of films of pyrites of leaf -like shapes, and produced by crystallisation. In the Middle Erian, however, more especially in North Ameri- ca, many species have been found (Figs. 32 to 24).* I have myself recorded more than thirty spe- cies from the Middle Erian of Canada, and these belong to sev- eral of the genera found in the Carboniferous, though some are peculiar to the Erian. Of the latter, the best known are per- haps those of the genus ArchcB- opteris (Fig. 24), do abundant in the plant-beds of Kiltorcan in Ireland, as well as in North America. In this genus the fronds are large and luxuriant, with broad obovate pinnules de- current on the leaf-stalk, and with simple sac-like spore-cases borne on modified pinnae. An- other very beautiful fern found Fio. 2'2.— Erian ferns ([New Brunswick), a, Aneimitea obtusa. 0, Neuroi)teris poly- morpha. f, Sphenopteris pilosa. N, Hymenophyllites subfurcatua. * For descriptions of these ferns, see reports cited above. TOE BRIAN OR DEVONLvN FORESTS. T8 Fio. 23. — Erian ferns (New Brunswick), b, Cyclopteris valida, and pinnule enlarged, n, Sphenopteris marginata^ and portion en'.arf^ed. B, Sphenopteris Ilartii, ci, Hijmehopkj/llites curtilonus. n, Hi/meno- phyUites (fersdarjfii, and portion enlarged, i, Alethopteris discrepaiis, K, Pecopteris serr'ulaia. ^, Fecopteris preciosa. a, J Idhopteris Ferleyi. I 74 TUE GEOLOGICAL HISTORY OF PLANTS. ; with ArchcBopteris is that which I have named Platyphyl- lum, and which grew on a creeping stem or parasitically on stems of other i)lants, and had marginal fructification.* Fio. 24. — Archcpopteris Jacksoni, Dawson (Maine). An Upper Erian fern, a, 6, Pinnules sliowing venation. * " Reports on Fossil Plants of the Devonian and Upper Silurian of Canada," 1871, &c. L THE BRIAN OR DEVONIAN FORESTS. 75 Another very remarkable fern, wlilch some botanists have supposed may belong to a higher group than the ferns, is Megalopteris (Fig. 2G). Some of the Erian ferns attained to the dimensions of tree-ferns. Large stems of these, which must have floated out far from land, have been found by Newberry in the marine limestone of Ohio {Caulopteris antiqua and C. peregrina, Newberry),* and Prof. Hall has found in the Fig. 25. — An Erian tree-fern. Caulopteris Lochvoodi^ Dawson, reduced. (From a specimen from Gilboa, New \ork.) Upper Devonian of Gilboa, New York, the remains of a forest of tree-ferns standing in situ with their great masses of aerial roots attached to the soil in which they grew {Caulopteris LocTciuoodi, Dn.).f These aerial roots introduce us to a new contrivance for strengthening the stems of plants by sending out into the soil multitudes of cord-like cylindrical roots from A ■ i| !; I (■ I * "Journal of the Geological Society," 1811. t Ibid. IMAGE EVALUATION TEST TARGET (MT-3) 1.0 I.I S4 5 :50 01 US IIIM illlM IIM 1.8 1.25 1.4 1.6 ^ 6" — ► ^ V] /a (P r 'V (? / ■/^, Photographic Sciences Corporation \ S V t •^ \\ % V ^V <^ ■>v 6^ .> -%^ 23 WEST MAIN STREET WEBSTER, NY. 14580 (716) 872-4503 7^ lit 76 THE GEOLOGICAL HISTORY OF PLANTS. f various heights on the stem, and which form a series of stays like the cordage of a ship. This method of support FiQ. 2Q.—Me(falopteri8 Dawsoni, Ilartt (Erian, New Brunswick), rt, Frag- ment of pinna, h, Point of pinnule, c, Venation. (Tlie midrib is not accurately given in this figure.) still continues in the modern tree-ferns of the tropics and the southern hemisphere. In one kind of tree-fern THE BRIAN OR DEVONIAN FORESTS. 77 stem from the Erian of New York, there is also a special arrangement for support, consisting of a series of pecul- iarly arranged radiating plates ^'f scalariform vessels, not exactly like those of an exogenous stem, but doing duty for it {A steropteris).* Similar plants have been described from the Erian of Falken- berg, in Germany, and of Saalfeld, in Thuringia, by Goep- pert and linger, and are referred to ferns by the former, but treated as doubtful by the latter, f This peculiar type of tree- fern is apparently a precursor of the more exogenous type of Heterangium, recent- ly described and re- ferred to ferns by Williamson. Here, again, we have a me- chanical contrivance now restricted to higher plants appro- priated by these old cryptogams. The history of the ferns in geological time is remark- ably different from that of the Lycopods ; for while the * "Journal of the Geological Society," London, 1881. t " Sphenopteris Refracta," Goeppert ; " Flora des Uebcrgangsge- birses." " Cladoxylon Mirabilc," Unger ; '* Palseontologie des Thuringer Waldes." Fio. 27. — Calamites radiatus (Erian, New Brunswick). I' 1 lii i li! ti 78 THE GEOLOGICAL HISTORY OF PLANTS. latter have long ago descended from their pristine emi- nence to a very humble place in nature, the former still, in the southern hemisphere at least, retain their arboreal dimensions and an- B ^1^ cient dominance. Cil!k. The family of the Equisetacem, or mare's-tails, was also represented by large species of Calamites and by Asterophyl- lites in the Erian ; but, as its headquar- ters are in the Car- boniferous, we may defer its considera- tion till the next chapter. (Figs. 27, 28.) Passi ng over these for the present, we find that the flower- ing plants are repre- sent d in the Eria,n forests by at least two types of Gym- nosperms, that of Taxincm or yews, and an extinct family, that of tlio Cordaites (Figs. 30, 31). The yew-trees are closely allied to the pines and spruces, and are often included with them in the family of Coniferce. They differ, however, in the habit of producing berries or drupe-like fruits instead of cones, and there is some reason to believe that this was the habit of the Erian trees of this group, though their wood in some in- stances resembles rather that of the Araucaria, or Nor- Fio. 28. — AsterophylUtes (Erian, New Bruns- wick). A, Asterophyllites latifoUa. b, Do,, apex of stem {\) fruit, c, c)>, A. scutigem. D, A. latifoha, larijer wliorl of loavea. d's Loaf. •" ' ^ THE BRIAN OR DEVONIAN FORESTS. 79 folk Island pine, than that of the modern yews. These trees are chiefly known to us by their mineralised trunks, which are often found like drift-wood on modern sand- banks embedded in the Erian sandstones or limestones. It often shows its structure in the most perfect man- ner in specimens penetrated by calcite or silica, or by pyrite, and in which the original woody matter has V Fio. 29. — Dadoxylon Ouangondianum, an Erian conifer, a. Frngraent Bhowinjr Sternberfria pi^li and wood: a, naedullary slieatli; ft, pith^ c, wood ; d. section of pith, b, Wood-cell ; a, hexatronal areola | i, pore, c, Lonj,'itudinal section of wood, showinj^, a, areolation, and b, medullary rays, d. Transverse section, sliowintr, a, wood-cells, and 6, limit of layer of growth, (b, c, u, highly magnified.) been resolved into anthracite or even into graphite. These trees have true woody tissues presenting that beau- tiful arrangement of pores or thin parts enclosed in cup- iike discs, which is characteristic of the coniferous trees, and which is a great improvement on the barred tissue already referred to, affording a far more strong, tough. m I> \ . »si 1 ! 80 THE GEOLOGICAL HISTORY OF PLANTS. and durable wood, such as we have iu our modern pines and yews (Fig. 29). These primitive pines make their appearance in the Middle Brian, in various parts of America, as well as in Scotland and Germany, and they are represented by wood indicating the presence of several species. I have myself indicated and described five species from the Erian of Canada and the United States. From the fact that these trees are represented by drifted trunks embedded in sand- stones and marine limestones, we may, perhaps, infer that they grew on the rising grounds of the Erian land, and that their trunks were carried by river-floods into the sea. No instance has yet certainly occurred of the discovery of their foliage or fruit, though there are some fan-shaped leaves usually regarded as ferns which may have belonged to such trees. These in that case would have resembled the modern GingTco of China, and some of the fruits re- ferred to the genus Cardiocarpum may have been pro- duced by them. Various names have been given to these trees. I have preferred that given by linger, Dadoxylon, as being more non-committal as to affinities than the others.* Many of these trees had very long internal pith-cylinders, with curious transverse tubulae, and which, when preserved separately, have been named Sternhergia. Allied to these trees, and perhaps intermediate between them and the Cycads, were those known as Cordaites (Fig. 30), which had trunks resembling those of Dadoxy- lon, but with still larger Sternhergia piths and an internal axis of scalariform vessels, surrounded by a comparatively thin woody cylinder. Some of them have leaves over a foot in length, reminding one of the leaves of broad-leaved grasses or iridaceous pi ts. Yet their flowers and fruit seem to have been more nearly allied to the yews than to any other plants (Fig. 31). Their stems were less woody * Araucaritca, Goeppert ; Arattearioxi/lon, Kraus. THE BRIAN OR DEVONIAN FORESTS. 81 and their piths hirger than in the true pines, and some of the larger-leaved species must have had thick, stiff branches. They are regarded as constituting a separate family, intermediate between pines and cycads, and, bc- Fio. 30. — Cordaites Rohhii (Erian, New Brunswick), or, Group of young leaves, i, Point of leaf. <•, Base of leaf rf, Venation, magnified. ginning in the Middle Devonian, they terminate in the Permian, where, however, some of the most gigantic spe- cies occur. In so far as the form and structure of tlie leaves, stems, and fruit are concerned, there is marvel- lously little difference between the species found in the 9 82 THE GEOLOGICAL HISTORY OF PLANTS, Erian and the Permian. They culminated, however, in the Carboniferous period, and the coal-fields of southern France have proved so far the richest in their remains. Lastly, a single specimen, collected by Prof. James Hall, of Albany, at Eighteen-mile Creek, Lake Erie, has the structure of an ordinary angiospermous exogen, and has been described by me as Syringoxylon mirahile* Fio. 81. — Erian fruits, &c., some wymnospcnnous, and probably of Cordaites and Taxine trees (St. John, J^ew BrunsAvick). a, (Jnrdvocarpum cor- nutum. B, Cardiocarpum acutum. o, Cardiocarpum Crampii. d, Car- diocarpum £aile>/i. e, Trigonocarpum racemosum. e>, e", Fruits en- o, Anmtlaria acuminata. larfTcd. F, Antliolithes Deco' icttg, terophyllitea aeiculark. n> Fruit of the same, k {i young of A.), l, Pinnul ia dispalaiis (probably a root) H, As- Cardiocarpum This unique example is sufficient to establish the fact of the existence of such plants at this early date, unless some accident may have carried a specimen from a later forma- * « Journal of the Geological Society," vol. xviii. THE BRIAN OR DEVONIAN FORESTS. 83 tion to be mixed with Erian fossils. It is to be observed, however, that the non-occurrence of any similar wood in all the formations between the Upper Erian and the Mid- dle Cretaceous suggests very grave doubt as to the authen- ticity of the specimen. I record the fact, waiting further discoveries to confirm it. Of the character of the speci- men which I have described I entertain no doubt. We shall be better able to realise the significance and relations of this ancient flora when we have studied that of the succeeding Carboniferous. We may merely remark here on the fact that, in these forests of the Devonian and in the marshes on their margins, we find a wonder- ful expansion of the now modest groups of llhizocarps and Lycopods, and that the flora as a whole belongs to the highest group of Cryptogams and the lowest of Phae- nogams, so that it has about it a remarkable aspect of mediocrity. Further, while there is evidence of some variety of station, there is also evidence of much equality of climate, and of a condition of things more resembling that of the insular climates of the temperate portions of the southern hemisphere than that of North America or Europe at present. The only animal inhabitants of these Devonian woods, so far as known, were a few species of insects, discovered by Hartt in New Brunswick, and described by Dr. Scud- der. Since, however, we now know that scorpions as well as insects existed in the Silurian, it is probable that these also occurred in the Erian, though their remains have not yet been discovered. All the known insects of the Erian woods are allies of the shad-flies and grasshop- pers {Neuroptera and Orthopterd), or intermediate be- tween the two. It is probable that the larvae of most of them lived in water and fed upon the abundant vegetable matter there, or on the numerous minute crustaceans and worms. There were no land vertebrates, so far as known, but there were fishes {Dipterus, etc.), allied to the mod- 84 THE GEOLOGICAL HISTORY OF PLANTS. eni Barramunda or Ceratodus of Australia, and with teeth suited for grinding vegetable food. It is also possi- ble that some of the smaller plate-covered fishes (Placo- ganoids, like PterichtJn/s) might have fed on vegetable matter, and, in any case, if they fed on lower animals, the latter must have subsisted on plants. I mention these facts to show that the superabundant vegetation of this age, whether aquatic or terrestrial, was not wholly useless to animals. It is quite likely, also, that we have yet much to learn of the animal life of the Erian swamps and woods. NOTES TO CHAPTER III. I. — Classification of Spoban'gites. It is, of course, very unsatisfactory to give names to mere frag- ments of plants, yet it seems very desirable to have some means of arranging them. With respect to the organisms described above, which were originally called by me Sporangites, under the sup- position that they were Sporangia rather than spores, this name has so far been vindicated by the discovery of the spore-cases belong- ing to them, so that I think it may still be retained as a provisional name; but I would designate the whole a,s Protosalviniw, meaning thereby plants with rhizocarpean affinities, though possibly when better understood belonging to different genera. We may under these names speak of their detached discs as macrospores and of their cellular envelopes as sporocarps. The following may be recog- nized as distinct forms : 1. Protosalviiiia Huronensis, Dawson, Syn., Sporangites Iluron- ensts, " Report on Erian Flora of Canada," 1871. — Macrospores, in the form of discs or globes, smooth and thick-walled, the walls pene- trated by minute radiating pores. Diameter about one one-hun- dredth of an inch, or a little more. When m situ several macro- spores are contained in a thin cellular sporoearp, probably globular in form. From the Upper Erian, and perhaps Lower Carboniferous shales of Kettle Point, Lake Huron, of various places in the State of Ohio, and in the shale boulders of the boulder clay of Chicago and vicinity. First collected at Kettle Point by Sir W. E. Logan, and 1 TUE BRIAN OR DEVONIAN FORESTS. 85 in Ohio by Prof. Edward Orton, and at Chicago by Dr. IT. A. John- son and Mr. B. W. Thoina.s, also in New Yorlt by Prof. J. M. Clarke. The inacrospores collected l)y Mr. Thomas from the Chicago clays and shales conform closely to those ot Kettle Point, and prol)- ably belong to the same species. Some of them are thicker in the outer wall, and show the pores much more distinctly. These have been called by Mr. Thomas »S'. Chicagoennin, and n>ay be regarded as a varietal form. Specimens isolated from the shale and mounted dry, show what seems to have been the hilum or scur of attachment better than those in balsam. Sections of the Kettle Point shale show, in addition to the ma- crospores, wider and thinner shreds of vegetable matter, which I am inclined to suppose to be remains of the sporocarps. 2. Protosalvinia (SporangUesJ Braziliensis, Dawson, " Canadian Record of Science," 1883. — Macrospores, round, smooth, a little longer than those of the last species, or about one seventy-fifth of an inch in diameter, enclosed in round, oval, or slightly renifonn sporocarps, each containing from four to twenty-four macrospores. Longest diameter of sporocarps tliree to six millimetres. Structure of wall of sporocarps hexagonal cellular. Some sporocarps show no macrospores, and may possibly contain microspores. The specimens are from the Erian of Brazil. Discovered by Mr. Orville Derby. The formation, according to Mr. Derby, consists of black shales be- low, about three hundred feet thick, and containing the fucoid known as Spirophyton, and probably decomposed vegetable matter. Above this is chocolate and reddish shale, in which the well-preserved speci- mens of Pi-otosalvinia occur. These beds are very widely distributed, and abound in Protosalvinia and Spirophyton. 3. Protosalvinia (Sporangites) bilobata, Dawson, "Canadian Record of Science," 1883. — Sporocarps, oval or reniform, three to six millimetres in diameter, each showing two rounded prominences at the ends, with a depression in the middle, and sometimes a raised neck or isthmus at one side connecting the prominences. Structure of sporocarp cellular. Some of the speci- mens indicate that each prominence or tubercle contained several macrospores. At first sight it would be easy to mistake these bodies for valves of Beyrichia. Found in the same formations with the last species, though, in so far as the specimens indicate^ not precisely in the same beds. Col- lected by Mr. Derby. 4. P-otosalvinia Clarkei, Dawson, P. bilobata, Clarke, " American Journal of Science." — Macrospores two-thirds to one millimetre in Hi M ■Si ' ! a I HI 66 TUE GEOLOGICAL HISTORY OF PLANTS. diameter. One, two, or three contained in enoh sporoearp, which is cellular. The macroaporcs have very thick walls with radiating tor- tuous tubes. Unless this structure is a result of mineral crystallisa- tion, these macrospores must have had very thick walls and must have resemlled in structure the thickened cells of stone fruits and of the core of the pear, or the tests of the Silurian and Erian seeds known as Pachytheca, though on a smaller scale. It is to bo observed that bodies similar to these occur in the Bog- head earthy bitumen, and have been described by Credner. I have found similar bodies in the so-called " Stellar coal " of the coal district of Pictou, Nova Scotia, some layers of which are filled with them. Tiiey occur in groups or patches, which seem to be en- closed in a smooth and thin membrane or sporocarp. It is quite likely that these bodies are generically distinct from Protosalvinia. 5. Protosalmiia punctata, Newton, " Geological Magazine," New Series, December 2d, vol. ii, — Mr. Newton 'is named the discs found in the white coal and Tiusmanite, Tasmanites, the species be- ing Tasmanites pnnctatus, but as my name Sporangites had priority, I do not think it necessary to adopt this term, though there can be little doubt that these organisms are of similar character. The same remark may be made with reference to the bodies described by Hux- ley and Newton as occurring in the Better-bed coal. In Witham's "Internal Structure of Fossil Vegetables," 1833, Plate XI, are figures of Lancashire cannel which shows Sporangites of the type of those in the Erian shales. Quckett, in his " Report on the Torbane Hill Mineral," 1854, has very well figured similar structures from the Methel coal and the Lesmahagow cannel coal. These are the earliest publications on the subject known to me ; and Quekett, though not understanding the nature of the bodies he observed, holds that they are a usual ingredient in cannel coals. II. — The Nature and Affinities of Ptilophyton. {Lycopodites Vanuxemii of " Report on Devonian and Upper Silurian Plants," Part I., page 35. L. plumula of " Report on Lower Carboniferous Plants," page 24, Plate I., Figs. 7, 8, 9.) In the re- ports above referred to, these remarkable pinnate, frond-like objects were referred to the genus Lycopodites, as had been done by Goep- pert in his description of the European species Lycopodites pennce- formis, which is very near to the American Erian form. Since 1871, however, there have been many new specimens obtained, and very various opinions expressed as to their affinities. While Hall has named some of them Plumalina, and has regarded them as animal --i: THE ERIAN OR DEVONIAN FORESTS. 87 V structures, allied to hydroids, Lesquereux has dcscriborl some of the Carboniferous forms under the generic name 2'rorhnphi/llum, which is, however, more appropriate to plants with vertieillate leaves which are included in this genus. Before I had seen the publications of Hall and Lesquereux on the subject, I had in a paper on "Scottish Devonian Plants " * separated this group from the genus Lycopodites, and formed for it the genus Ptilophyton, in allusion to th(> feather- like aspect of th(! species. My reasons for this, and my present in- formation as to the nature of these plants, may bo stated as follows: Schimper, in his '* Paheontologie Vegetale " (possibly from Inat- tention to the descriptions or want of access to specimens), doubts the lycopodiaceous character of species of Lycopodites described in my published papers on plants of the Devonian of America and in my Report of 1871. Of these, L, Richardnoni and L, Mntthen'i are un- doul)tedly very near to the modern genus Lyrnpodiutn. L. Vaniir- einii is, I admit, more problematical ; but Schimper could scarcely have supi)osed it to be a fern or a fucoid allied to Caulerpa had he observed that both in my species and the allied L. peniupformla of Goeppert, which he does not appear to notice, the pinnules are ar- ticulated upon the stem, and leave scars where they have fallen oil. When in Belfast in 1870, my attention was again directed to the af\ lities of these plants by finding in Prof. Thomson's collection a sp-oim'^n from Caithness, which shows a plant apparently of this kind, v.ith the same long narrow pinna; or leaflets, attached, how- ever, to thicker stems, and rolled up in a circinate manner. It seems to be a plant in vernation, and the parts are too much c.owded and pressed together to admit of being accurately figured or described ; but 1 think I can scarcely be deceived as to its true nature. The circinate arrangement in this case would favour a relationship to ferns ; but some lycopodiaceous plants also roll themselves in this way, and so do the branches of the plants of the genus Psilophyton. (Fig. 17, supra.) The specimen consists of a short, erect stem, on which are placed somewhat ^tout alternate branches, extending obliquely outward and then curving inward in a circinate manner. The lower onos appear to produce on their inner sides short lateral branchlets, and upon these, and also upon the curved extremities of the branches, are long, narrow, linear leaves place' '"n a crowded manner. The specimen is thus not a spike of fructi.. —..ion, but a young stem or branch in ver- nation, and which when unrolled would be of the form of those * "Canadian Naturalist," 1878. 88 THE GEOLOGICAL HISTORY OF PLANTS. :■ r; Hi ll peculiar pinnate Lycopodites of which L. Vanuxemii of the Ameri- can Devonian and L. pennrpformis of the European Lower Carbon- iferous are the types, and it shows, what might have been anticipated from other specimens, that they were low, tufted plants, circinate in vernation. The short stem of this plant is simply furrowed, and bears no resemblance to a detached branch of Lycopodites Milleri which lies at right angles to it on the same slab. As to the affinities of the singular type of plants to which this specimen belongs, I may quote from my " Ileport on the Lower Carboniferous Plants of Canada." in which I have described an allied species, L. plumula : " The botanical relations of these plants must remain subject to doubt, until either their internal structure or their fructification can be discovered. In the mean time I follow Goeppert in placing them in what we must regard as the provisional genus Lycopodites. On the one hand, they are not unlike the slender twigs of Taxodium and similar Conifers, and the highly carbonaceous character of the stems gives some colour to the supposition that they may have been woody plants. On the other hand, they might, so far as form is con- cerned, be placed with Alga^ of the type of Brongniart's Chondrites ohtusi's, or the modern Caulerpa j)lumaria. Again, in a plant of this type from the Devonian of Caithness to which I have referred in a former memoir, the vernation seems to have been circinate, and Schimper has conjectured that these plants may be ferns, which seems also to have been the view of Shumard." On the whole, these plants are allied to Lycopods rather than to ferns ; and as they constitute a small but distinct group, known only, so far as I am aware, in the Lower Carboniferous and Erian or De- vonian, they deserve a generic name, and I proposed for them in my " Paper on Scottish Devonian Plants," 1878, that of Ptilophyton, a name sufficiently distinct in sound from Psilophyton, and expressing very well their peculiar feather-like habit of growth. The genus was doflned as follows : " Branching plants, the branches tearing long, slender leaves in two or more ranks, giving them a feathered appearance ; vernation circinate. Fruit unknown, but analogy would ind.cato that it was borne on the bases of the leaves or on modified branches with shorter leaves." The Scottish specimen above referred to was named Pt. Thom- 8oni, and was characterised by its densely tufted form and thick branches. The other species known are: Pi. penna'forinis, Goep- pert, L. Carboniferous ; Pt. Vanuxemii, Dawson, Devonian ; Pt, plumula, Dawson, L. Carboniferous. TUE BRIAN OR DEVONIAN FORESTS. 89 Shnmar(Vs Filicites gracilis, from the Lavonian of Ohio, and Stur's Pinites antecedens, from the Lower Carboniferous of Silesia, may possibly belong to the same genus. The Scottish specimen re- ferred to is apparently the first nppcarance of this form in the Devonian of p]urope. I have at a still later date had opportunities of studying con- siderable series of these plants collected by Prof. Williams, of Cornell University, and prepared a note in reference to them for the Ameri- can Association, of which, however, only an abstract has been pub- lished. I have also been favoured by Prof. Losquereux and Mr. Lacoe, of Pitt3ton, with the opportunity of- studying the specimens referred to Trochophi/llum. Prof. Williams's specimens occur in a dark shale associated with remains of land-plants of the genera Psilophyton, Rhodea, &c.. and also marine shells, of which a small species of RhynchoneUa is often attached to the stems of the Ptilophylon. Thus these organisms have evidently been deposited in marine beds, but in association witii land-plants. The study of the specimens collected by Prof. Williams develops the following facts: (1) Tlie plants are not continuous fronds, but slender stems or petioles, with narrow, linear leaflets attached in a pinnate manner. (2) The pinnules are so articulated that they break off, leaving delicate transverse scars, and the lower parts of the stems are often thus denuded of pinna> for the length of one or more inches. (3) Tlie stems curve in such a manner as to indicate a cir- cinate vernation. (4) In a few instances the fronds were observed to divide dichotomously toward the top ; but this is rare. (5) There are no indications of cells in the pinnules; but, on the other hand, there is no appearance of fructification unless the minute granules which roughen some of the stems are of this nature. ((!) The stems seem to have been lax and flexuous, and in some instances they seem to have grown on the petioles of ferns preserved with them in the same beds. (7) The frequency of the attachment of small braehio- pods to the specimens of Ptiloplujton would seem to indicate that the plant stood erect in the water. (8) Some of the specimens show so much carbonaceoiis matter as to indicate that the pinnules were of considerable consistency. All these characters are those rather of an aquatic plant than of an annual organism or of a land-plant. The specimens communicated by Prof. Lestiuoreux and Mr. Lacoe are from the Lower Carboniferous, and evidently represent a different specie with similar slender pitted stems, often partially denuded of pinnules below ; but the pinnules are much broader and I ^i i , \ i l!|.^ THE GEOLOGICAL HISTORY OF PLANTS. more distant. They are attached by very narrow bases, and ap- parently tend to lie on a plane, though they may possibly have been spirally arranged. On the same slabs are rounded sporangia or maerospores like those of Lepidodendron, but there is no evidence that these belonged to Trochophyllvm. On the stems of this plant, however, there are small, rounded bodies apparently taking the places of some of the pinnules. These may possibly be spore-cases ; but they may be merely imperfectly developed pinnules. Still the fact that similar small granules appear on the stems of the Devonian species, favours the idea that they may be organs of fructification. The most interesting discovery, however, which results from the study of Mr. Lacoe's specimens, is that the pinnules were cylindrical and hollow, and probably served to iioat the plant. This would account for many of the peculiarities in the appearance and mode of occurrence of the Devonian Ptilophyton, which arc readily ex- plained if it is supposed to be an aquatic plant, attaching itself to the stems of submerged vegetable remains and standing erect in the water by virtue of its hollow leaves. It may well, however, have been a plant of higher organisation than the AlgiT, though no doubt cryptogamous. The species of Ptilophyton will thus constitute a peculiar group of aquatic plants, belonging to the Devonian and Lower Carbonif- erous periods, and perhaps allied to Lycopods and Pillworts in their organisation and fruit, but specially distinguished by their linear leaves serving as floats and arranged pinnately on slender stems. The only species yet found within the limits of Canada is Pt. phi- mula, found by Dr. Iloneyman in the Lower Carboniferous of Nova Scotia ; but as Pt. Vanuxemii abounds in the Erian of New York, it will no doubt be found in Canada also. III. — Tree-Ferns of the Erian Period. As the fact of the occurrence of true tree-ferns in rocks so old as the Middle Erian or Devonian has been doubted in some quar- ters, the following summary is given from descriptions published in the "Journal of the Geological Society of Loudon" (1871 and 1881), where figures of the species will be found : Of the numerous ferns now known in the Middle and Upper Devonian of North America, a great number are small and delicate species, which were {)robably herbaceous ; but there are other species which may have been tree-ferns. Little definite information, how- ever, has, until recently, been obtained with regard to their habit of growth. THE BRIAN OR DEVONIAN FORESTS. 91 The only species known tc ne in the Devonian of Europe is the Canlopteris Peachii of Salter, figured in the '• Quarterly Journal of the Geological Society " for 1858. The original specimen of this I had an opportunity of seeing in London, through the kindness of Mr. Etheridge, and have no doubt that it is the stem of a small arborescent fern, allied to the genus Caiilopteris, of the coal forma- tion. In my paper on the Devonian of Eastern America (" Quarterly Journal of the Geological Society," 1802), I mentioned a plant found by Mr. Richardson at Perry, as possibly a species of Metjophyton, using that term to denote those stems of tree-ferns which have the leaf-scars in two vertical series ; but the specimen was obscure, and I have not yet obtained any other. Moie recently, in 1869, Prof. Hall placed in my hands an inter- esting collection from Gilboa, New York, and Madison County, New York, including two trunks surrounded by aerial roots, which I have described as Psaronius fexiilis and P. Erianus, in my " Revision of the Devonian Flora," read before the Royal Society.* In the same collection were two very large petioles, Rhachiopteria gigantea and li. palmata, which I have suggested may have belonged to tree-ferns. My determination of the species of Psaronius, above mentioned, has recently been completely confirmed by the discovery on the part of Mr. Lockwood, of Gilboa, of the upper part of one of these stems, with its leaf-scars preserved and petioles attached, and also by some remarkable specimens obtained by Prof. Newberry, of New York, from the Corniferous limestone of Ohio, which indicate the exist- ence there of three species of tree-ferns, one of them with aerial roots similar to those of the Gilboa specimens. The whole of these specimens Dr. Newberry has kindly allowed me to examine, and has permitted me to describe the Gilboa specimen, as connected with those which I formerly studied in Prof, flail's collections. The specimens from Ohio he has himself named, but allows me to notice them here by way of comparison with the others. I shall add some notes on specimens found with the Gilboa ferns. It may be further observed that tlie Gilboa specimens are from a bed containing erect stumps of tree-ferns, in the Chemung group of the Upper Devonian, while .hose from Oliio are from a marine limestone, belonging to the lower part of the Middle Devonian. 1. Caulopteris Lockwoodi, Dawson. — Trunk from two to three * Abstract in " Proceedinps of the Royal Society," May, 1810; also "Report on Brian Plants of Canada," \671. m^ 11 ^m ^ m m 1'^ h I i ! 1 I 92 THE GEOLOGICAL HISTORY OF PLANTS. inches in diameter, rugose longitudinally. Leaf-scars broad, rounded above, and radiatingly rugose, with an irregular scar below, arranged spirally in about five ranks; vascular bundles not distinctly pre- served. Petioles slender, much expanded at the base, dividing at first in p. piimate manner, and afterwards dichotomously. Ultimate pinnae with remains of numerous, apparently narrow pinnules. This stem is probably the upper part of one or oth r of the species of Psaronius found in the sanie bed (P. Erianus, Dawson, and P. fextilis, Dawson).* It appears to have been an erect stem embedded in situ in sandstone, and preserved as a cast. The stem is small, being only two inches, or a little more, in diameter. It is coarsely wrinkled longitudinally, and covered with large leaf- scars, each an inch in diameter, of a horseshoe-shape. The peti- oles, five of which remain, separate from these scars with a distinct articulation, except at one point near the base, where probably a bundle or bundles of vessels passed into the petiole. They retain their form at the attachment to the stem, but a little distance from it they are flattened. They are inflated at the base, and some- what rapidly diminish in size. The leaf-scars vary in form, and are not very distinct, but they appear to present a semicircular row of pits above, largest in the middle. From these there proceed down- ward a series of irregular furrows, converging to a second and more obscure semicircle of pits, within or below which is the irregular scar or break above referred to. The attitude and form of the petioles will be seen from Fig. 24, supra. The petioles are broken off within a few inches of the stem ; but other fragments found in the same beds appear to show their continuation, and some remains of their foliage. One specimen shows a series of processes at the sides, which seem to be the re- mains of small pinna), or possibly of spines on the margin of the petiole. Other fragments show the division of the frond, at first in u pinnate manner, and subsequently by bifurcation ; and some frag- ments show remains of pinnules, possibly of fertile pinnules. These are very indistinct, but would seem to show that the plant ap- proached, in the form of its fronds and the arrangement of its fructification, to the Cyclopterids of the subgenus Aneimites, one of which (Atieimites Acadica), from the Lower Carboniferous of Nova Scotia, I have elsewhere described as probably a tree-fern.f The * Memoir on Devonian Flora, " Proceedings of the Royal Society," May, 1870. t "Quarterly Journal of the Geological Society," 1860. . - THE BRIAN OR DEVONIAN FORESTS. 93 fronds were evidently different from those of Archrpopteris,* a genus characteristic of tlie same beds, but of very different habit of growth. This accords with the fact tliat there is in Prof. Hall's collection a mass of fronds of Cydopteris (Archceopteris) Jarksoni, so arranged as to make it probable that the plant was an herbaceous fern, pro- ducing tufts of fronds on short stems in the ordinary way. The obscurity of the leaf-scars may render it doubtful whether the plant above described should be placed in the genus Caulopferis or in Stem- matopteris ; but it appears most nearly allied to the former. The genus is at present, of course, a provisional one; but I have thought it only justice to the diligent labours of Mr. Lockwood to name this curious and interesting fossil Caulopferis Lockwoodi, I have elsewhere remarked on the fact that trunks, and petioles, and pinnules of ferns are curiously dissociated in the Devonian beds — an effect of water-sorting, characteristic of a period in which the conditions of deposition were so varied. Another example of this is, that in the sandstones of Gaspe Bay, which have not as yet af- forded any example of fronds of ferns, there are compressed trunks, which Mr. Lockwood's specimens allow me at least to conjecture may have belonged to tree-ferns, although none of them are suffi- ciently perfect for description. Mr. Lockwood's collection includes specimens of Psaronius fex- tilis ; and in addition to these there are remains of erect stems some- what different in character, yet possibly belonging to the higher parts of the same species of tree-fern. One of these is a stem crushed in such a manner that it does not exhibit its form with any distinctness, but surrounded by smooth, cylindrical roots, radiating- from it in bundles, proceeding at first horizontally, and then curving down- ward, and sometimes terminating in rounded ends. They resemble in form and size the aerial roots of Psaronius Eriarms ; and I believe them to be similar roots from a higher part of the stem, and some of '^ \em young and not prolonged sufficiently far to reach the ground. This specimen would thus represent the stem of P. Erianus at a higher level than those previously found. We can thus in imagirui- tion restore the trunk and crown of this once graceful tree-fern, though we have not the detail of its fronds. Mr, Lockwood's collections also contain a specimen of the large fern-petiole which I have named Rhachiopteris punctata. My original specimen was obtained by Prof. Hall from the same horizon in New York. * The genus to which the well-known Cyclopteris {Adianiites) Hiber- nieus of the Devonian of Ireland belongs. n t i 91 THE GEOLOGICAL HISTORY OF PLANTS. W That of Mr. Lot kwood is of larger size, but retains no remains of the frond. It must have belont^od to a si)0('ics quite distinct from faw- lopteria Loclcwoodi, but which may, like it, have been a tree-fern. 2. Caulopte'iis anticjua, Newberry. — This is a flattened stem, on a slab of limestone, containing liiachiopods, Trilobites, &c., of the Corniferous limestone. It is about eighteen inches in length, and three and a half inches in average breadth. The exposed side shows about twenty-two large leaf -scars arranged spirally. Each leaf, where broken off, has left a rough fracture ; and above this is a semicircular impression of the petiole against the stem, which, as well as the surface of the bases of the petioles, is longitudinally striated or tuberculated. The structures are not preserved, but merely the outer epidermis, as a coaly film. The stem altogether much resembles Caulopteris Peachii, but is of larger size. It differs from C. Lockwoodi in the more elongated leaf-bases, and in the leaves being more remotely placed; but it is evidently of the same general character with that species. 3. Caulopteris (Protopteris) peregrina, Newberry. — This is a much more interesting species than the last, as belonging to a ge- neric or subgeneric form not hitherto recognised below the Carbonif- erous, and having its minute structure in part preserved. The specimens are, like the last, on slabs ot marine limestone of the Corniferous formation, and flattened. One represents an uj)per portion of the stem with leaf-scars and remains of petioles ; another a lower portion, with aerial roots. The upper part is three inches in diameter, and about a foot in length, and shows thirty leaf-scars, which are about three-fourths of an inch wide, and rather less in depth. The upper part presents a distinct r'>unded and sometimes double marginal line, sometimes with a slight depression in the mid- dle. The lower part is irregular, and when most perfect shows seven slender va«<^nlar bundles, passing obliquely downward into the stem. The more [. 3t leaf-bases have the structure preserved, and show a delicate, thin-walled, oval parenchyma, while the vascular bundles show scalariform vessels with short bars in several rows, in the man- ner of many jnodern ferns. Some of the scars show traces of the hippocrepian mark characteristic of I^otnpferis ; and the arrange- ment of the vascular bundles at the base of the scars is the same as in that genus, as are also the general form and arrangement of the scars. ( 1 careful examination, the species is indeed very near to the typical P. Stembergii, as figured by Corda and Schimper.* * Corda, " Beitrago," PI. 48, copied by Schimper, PI. 52. THE ERIAN OR DEVONIAN FORESTS. 95 The genus Protopfrris of Stornborg, tliough the original species (P. punctata) appears as a Lepidodcndion in his earlier plate (Plate 4), and as a Siyilldria {S. jxuffafu) in Brongniart's great work, is a true tree-fern; and the structure of one sjuHMes (P. Cottai) has been beautifully figuered by Corda. The species hitherto descril)ed are from the Carboniferous and Permian. The second specimen of this species represents a lower part of the stem. It is thirteen inches long and about four inches in diam- eter, and is covered with a mass of flattened aerial rov>ts lying paral- lel to each other, in the manner of the Psaromtes of the coal-forma- tion and of P. J'Jrianus of the Upper Erian or Devonian. 4. Asteropteris novehoracensis, gen. and sp. n. — The geniis An- teropteris is established for stems of ferns having the axial portion composed of vertical radiating plates of scalariform tissue embedded in parenchyma, and having the outer cylinder composed of elongated cells travei*sed by leaf-bundles of the type of those of Zijgnpteris. The only species known to me is represented by a stem 2*5 cen- timetres in diameter, slightly wrinkled and pitted externally, per- haps by traces of aerial roots which have perished. The transverse section shows in the centre four vertical plates of scalariform or im- perfectly reticulated tissue, placed at right angles to each other, and united in the middle of the stem. At a short distance from the centre, each of these plates divides into two or three, so as to form an axis of from ten to twelve radiating plates, with remains of cellu- lar tissue filling the angidar interspaces. The greatest diameter of this axis is about 1*5 centimetre. p]xterior to the axis the stem con- sists of elongated colls, with somewhat thick walls, and more dense toward the circumference. The walls of these cells present a curious reticulated appearance, apparently caused by the cracking of the ligneous lining in consequence of contraction in the process of car- bonization. Embedded in this outer cylinder are about twelve vas- cular bundles, each with a dumb-bell-shaped group of scalariform vessels enclosed in a sheath of thick-walled fibres. Each bundle is opposite to one of the rays of the central axis. The specimen shows about two inches of the length of the stem, and is somewhat bent, aj)parently by pressure, at one end. This stem is evidently that of a small tree-fern of a type, so far as known to me, not before described,* and constituting a very complex and symmetrical form of the group of PaliBozoic ferns allied * Prof, Williamson, to whom I have sent a tracing of the structure, agrees with mc that it is new. (1 90 THE GEOLOGICAL HISTORY OF PLANTS. ii m j ■ -■ 7 1 ' • t m m. to the penus Zyffopteris of Sohimper. The central axis alone has a curious resembhince to the peculiar stem described by linger ("De- vonian Flora of Thuringia ") under the name of Cladoxylon mira- hile ; and it is just possible that this latter stem may be the axis of sonic allied plant. The large aerial roots of some modern tree- ferns of the genus Angiopteria have, however, an analogous radiating structure. The specimen is from the collection of Berlin IT. Wright, Esq., of Penn Yan, New York, and was found in the Portage group (Upper Erian) of Milo, New York, where it was associated with large petioles of ferns and trunks of Lepidodendra, probably L. Chemungetise and L. prinuevum. The occurrence of this and other stems of tree-ferns in marine beds has recently been illustrated by the observation of Prof. A. Agassiz that considerable quantities of vegetable mutter can be dredged from great depths in the sea on the leeward side of the Caribbean Islands. The occurrence of these trunks further connects itself with the great abundance of large petioles {Rhachiopteris) in the same beds, while the rarity of well-preserved fronds is explained by the coarseness of the beds, and also by the probably long macera- tion of the plant-remains in the sea-water. In connection with this I may refer to the remarkable facts re- cently stated by Williamson* respecting the stems known as Hete- rangium and Lyginodendron. It would seem that these, while having strong exogenous peculiarities, are really stems of tree-ferns, thus placing this family in the same position of advancement with the Lycopods and Equisetacece of the Coal period. • IV. — On Erian Trees of the Genus Dadoxylon, Under. {Araucarites of Goeppert, Araucarioxylon of Kraus.) Large woody trunks, carbonised or silicificd, and showing wood- cells with hexagonal areoles having oval pores inscribed in them, occur abundantly in some beds of the Middle Erian of America, and constitute the most common kind of fossil wood all the way to the Trias. They have in the older formations, generally, several rows of pores on each fibre, and medullary rays composed of two or more series of cells, but become more simple in these respects in the Per- mian and Triassic series. The names Araucarites and Araucarioxy- lon are perhaps objectionable, inasmuch as they suppose affinities to Araucaria which may not exist. Unger's name, which is non- * "Proceedings of the Royal Society," January 6, 1887. THE BRIAN OR DEVONIAN FORESTS. 97 committal, is tho.-eforo. T ihink, to be preferrcfl. In my "Acadian Geolojjy," and in my "Kiporr on the GeoIoj?y of Prince Edward Island,'' I have given reasons for hclievinj? tliat the foliage of some at least of these trees was that known w. Walrhm, and that they may have borne nutlets in the manner of Taxiue trees (7V/(70Hocnr/>»/m, &c.). Grand d'Eury has recently suggested that some of them may liave belonged to Cordnites, or to plants included in that somewhat varied and probably artificial group. The earliest discovery of trees of this kind in the Erian of America was that of Matthew and Ilartt, who found large trunks, which I afterwards described as Dadoi-yUm Ouangnnd ianum, in the Erian sandstone of St. John, New Brunswick, hence named by those geologists the " Dadoxylon sandstone." A little later, similar wood was found by Prof. Hall and Prof. Newberry in the Hamilton group of New York and Ohio^ and the allied wood of the genus Ormoinjlon was obtained by Prof. Hall in the Portage group of the former State. These woods proved to be specifically distinct from that of St. John, and wore named by me T). Halli, D. Newberryi, and Or- moxylon Eriaiuim. The three species of Dadojryhm agreed in hav- ing composite medullary rays, and would thus belong to the group Palfpoxyfon of Brongniart. In the case of Ormoxylon this character could not be very distinctly ascertained, but the medullary rays appeared to be simple. I am indebted to Prof. J. M. Clarke, of Amherst College, Massa- chusetts, for some well-preserved specimens of another species from the Genesee shale of Canandaigua, New York. They show small stems or branches, with a cellular pith surrounded with wood of coniferous type, showing two to three rows of slit-formed, bordered pores in hexagonal borders. The medullary sheath consists of pseudo-scalariform and reticulated fibres ; but the most remarkable feature of this wood is the structure of the medullary rays, which are very frequent, but short and simple, sometimes having as few as four cells superimposed. This is a character not before observed in coniferous trees of so great age, and allies this Middle Erian form with some Carboniferous woods which have been supposed to belong to Cordailes or Siyillaria. In any case this structure is new, and I have named the species Dadoxylon Clnrkiiy after its discoverer. The specimens occur, according to Prof. Clarke, in a calcareous layer which is filled with the minute shells of Styliola fissure.lla of Hall, believed to be a Pteropod ; and containing also shells of Goniatites and Gyroceras. The stems found are only a few inches in diameter, but may be branches of larger trees. ii! M 14 \ i i r ! 1 - I 1 98 THE GEOLOGICAL HISTORY OF PLANTS. It thus appears that wc already know flvo species of Coniferous trees of the goniis Dadoxylon in the IVIiddle Erian of America, an interesting confirmation of the facts otherwise known as to the great richness and variety of this ancient flora. The late Prof, (ioeppert informed me that he had recognised similar wood in the Devonian of Germany, and there can be no doubt that the fossil wood discovered by Hugh Miller in the Old Red Sanilstone of Scot- land, and described by Salter and McNab, is of similar character, and probably belongs to the genus Dadoxylon. Thus this type of Conif- erous tree seems to have been as well established and differentiated into species in the Middle Devonian as in the succeeding Carbonif- erous. I may here refer to the fact that the lower limit of the trees of this group coincides, in America, with the upper limit of those prob- lematical trees which in the previous chapter I have named Proto- gens {Nematophyton, Celluloxlyon,* Nematuxylon f ), though Apo- roxylon of linger extends, in Thuringia, up to the Upper Devonian (Cypridina schists), V. — Scottish Devonian Plants of Huon Miller and others. (Edinburgh Geological Society, 1877.) Previously to the appearance of my descriptions of Devonian plants from North America, Hugh Miller had described forms from the Devonian of Scotland, similar to those for which I proposed the generic name Pailophyton ; and I referred to these in this connection in my earliest description of that genus.ij: He had also recognised whr.L seemed to bo plants allied to Lycopods and Conifers. Mr. Peach and Mr. Duncan had made additional discoveries of this kind, and Sir J. Hooker and Mr. Salter had described some of these re- mains. More recently Messrs. Peach, Carruthers, and McNab have worked in this field, and still later* Messrs. Jack and Etheridge have summed up the facts and have added some that are new. The first point to which I shall refer, and which will lead to the other matters to be discussed, is the relation of the characteristic" Lepidodendron of the Devonian of eastern America, L. Gaspianum, to L. nothum of Unger and of Salter. At the time when I described this species I had not access to Scottish specimens of Lepidodendron * "Journal of the Geological Society," May, 1881. f Ibid., vol. six, 1863. X " Journal of the Geological Society," London, 1859. « Jbid., 1877. THE BRIAN OR DEVONIAN FORESTS. 09 from the Devonian, but these had been well fipirod nnd described by Salter, imtl had boon idontifiod with L,ni)thumoi Unjjor, a species evidently distinct from mine, as was also thai fif:;ured and described by Suiter, whether identical or not with Unger's species. In 1870 I had for the first time an opportunity to study Scottish specimens in the collection of Mr. Peacii ; anil on the evidence thus alfordod I stated confidently that these specimens represented a species distinct from L. Oaspianum, perhaps oven generically so.* It differs from L, Oaspianum in its habit of growth by developing small lateral branches instead of bifurcating, and in its foliage by the absence or obsolete character of the leaf-bases and the closely placed and some- what appressed leaves. If an ai)pearance of sw( lling at the end of a lateral branch in one specimen indicates a strobile of fructification, then its fruit was not dissimilar from that of the Canadian species in its position and general form, though it may have differed in details. On these grounds I declined to identify the Scottish species with L. Gaspianum. The Lepidodondron from the Devonian of Belgium described and figured by Crepin.f has a better claim to such identification, and would seem to prove that this species existed in Europe as well as in America. I also saw in Mr. Peach's collection in 1870 some fragments which seemed to me distinct from Salter's species, and possibly belonging to L. Gaspianum.X In the earliest description of Pmlophyton I recognised its prob- able generic alTinity with Miller's " dichotomous plants," with Salter's " rootlets," and with Goeppert's Haliserites Dechenianns, and stated that I had " little doubt that materials exist in the Old Red Sand- stone of Scotland for the reconstruction of at least one species of this genus." Since, however. Miller's plants had been referred to coniferous roots, and to fueoids, and Goeppert's Haliserites was a name applicable only to fueoids, and since the structure and fruit of my plants placed them near to Lycopods, I was under the neces- sity of giving them a special generic name, nor could I with cer- tainty alfirm their specific identity with any Euroi)ean species. The comparison of the Scottish specimens with woody rootlets, though incorrect, is in one respect creditable to the acumen of Salter, as in almost any state of preservation an experienced ej e can readily per- ceive that branchlets of Psilophyton must have 'oeen woody rather * "Report on Devonian Plants of Canada," ISVl. f "Observations sur quelques Plantes Fossiles des ddpots Devoni- ens. X " Proceedings of the Geological Society of London," March, 1871. ' ; ^ I s in 1, A 1:| f ft' I I it 19 f I 4 100 TUE GEOLOGICAL HISTORY OF PLANTS. than horbnronus, and their appearance is qxiito different from that of any true Alfitv. TIjo type of I'silnpfii/fon is my P. princepn, of wliich the whole of the parts and structures arc well iim. i, l, m, Bark, with leaf-soars, n, Bark, with Ical- Bcors of ol«i stem, o, Decorticated stem {Knorriu). THE CARBONIFEROUS FLORA. 121 Fio. 44. — LepidophloioK Arndianus, Dawson, a Icniciodondroid treo of tho coal-formation, a. Restoration, b, Tortion of hark (two thirds natural size), c, Ligneous surface of the same, f, Cone (two thirds natural size), o, Leaf (natural size), k, Portion of woody cvliiider, showitiar outer and inner series of vessels magnified, l, Scalaritorin vessels (highly magni- fied). M, Various forma of leaf-scarA and leaf-buses (natural size). 122 THE GEOLOGICAL HISTORY OF PLANTS. 'a !i if I ■I j lii son, of Manchester, to illustrate the structure of Cala- mites, and he has shown that these plants, like other cryptogams of the Carboniferous, had mostly stems with regular fibrous wedges, like those of exogens. The structure of the stem is, indeed, so complex, and differs so much in different stages of growth, and different states of preservation, that we are in danger of falling into the greatest confusion in classifying these plants. Sometimes what we call a Calamite is a mere cast of its pith showing longitudinal striae and constrictions at the nodes. Some- Fio. 45. — AderophijllUes, Spheiwph>/ll, Leaf enlarjjed. b, Annvlaria gphenophi/Uoidea. B', Leaf enlarged, o, Sphenophyllnm erosum. c», LeaHet enlar^d. c», Scalariform vessel of Sphenophyllum. d, Finnttlaria ramosissima^ probably a root. times we have the form of the outer surface of the woody cylinder, showing longitudinal ribs, nodes, and marks of the emission of the branchlets. Sometimes we have the outer surface of the plant covered with a smooth bark showing flat ribs, or almost smooth, and having at the nodes regular articulations with the bases of the verticil- THE CARBONIFEROUS FLORA, 123 late branchlefcs, or on the lower part of the stem the marks of the attachment of the roots. The Calamites grew in dense clumps, budding off from one another, sometimes at different levels, as the mud or sand accumu- lated about tlieir stems, and in some species there were creeping rliizomata or root-stocks (Figs. 46 to 49). But all Calamites were not alike in structure. In a recent paper* V I V. Fig. 46. — Calamites. A, C. Suckoril. B, C. Cistii. ( From " Acadian Geolo- gy-") ^' , Fio. 47.— .Erect Cala- mites, witli roots at- tached (Nova Sco- tia). Fig. 48.— Node of C. Cistii, with long leaves (Nova Sco- tlft), , Dr. Williaiuson describes three distinct structural types. What he regards as typical Calamites has in its woody zone wedges of barred vessels, with thick bands of cel- lular tissue separating tliem. A second type, which * " Memoirs of the Philosophical Society," Manchester, ISSS-'S?. ^v I 't i . ;:i 1 1 ; iV: ':\ '■'! -. ' J 1 ^^ mM ' H^ [f - f 124 THE GEOLOGICAL "'^""ORY OF PLANTS. he refers to Calamor' las woody bundles com- posed of reticulated altiporous fibres, with their porous sides parallel che medullary rays, which are better developed than in the previous form. The inter- vening cellular masses are composed of elongated cells. This is a decided advance in structure, and is of the type of those forms having the most woody and largest stems, (C) •T* (a) VAAV Fio. 49. — Erect Calamites {C. Suckovii), showing the mode of growth of new stems (i), and different forms of the ribs (a, c), (Pictou, Nova Scotia.) Half natural size. which Brongniart named Calamodendron (Fig. 50). A third form, to which Dr. Williamson seems to prefer to assign this last name, has the tissue of the woody wedges barred, as in the first, but the medullary rays are better developed than in the second. In this third form the intermediate tissue, or primary medullary rays, is truly fibrous, and with secondary medullary rays traversing it. My own observations lead me to infer that there was a fourth type of calamitean stem, less endowed with woody matter, and having a larger fistulous or cellular cavity than any of those described by Dr. Williamson. There is every reason to believe that all these various THE CARBONIFEROUS FLORA. 125 and complicated stems belonged to higher and nobler types of mare's-tails tiian those of the modern world, and that their fructification was equisetaceous and of the form known as Calamostachys. We have already seen that noble tree-ferns existed in the Erian period, and these were continued, and their number and variety greatly extended, in the Carbonifer- ous. In regard to the structure of their stems, and the method of supporting these by atrial roots, the tree-ferns of all ages have been nearly alike, and the form and structure of the leaves, except in some comparatively rare and exceptional types, has also been much the same. Any ordinary observer examining a collection of coal- formation ferns recognises at once tlieir kinship to the familiar brackens of our own time. Their fructification is, unfortunately, rarely preserved, so that we are not able, in the case of many species, to speak confidently of Fio. 50. — Stems of CalamoJendron and tissues magnified (Nova Scotia), a, 6, Casts of axis in sandstone, with woody envelope (reduced). c, d, Woody tissue (highly magnified). their affinities with modern forms ; but the knowledge of this subject has been constantly extending, and a suffi- cient amount of information has been obtained to enable us to say something as to their probable relationships. (Figs. 51 to 55.) The families into which modern ferns are divided are, it must be confessed, somewhat artificial, and in the case 1; i! I |i i II 12G TUE GEOLOGICAL HISTORY OF PLANTS. of fossil ferns, in wliich the fructification is for the most part wanting, it is still more so, depending in great part on the form and venation of the divisions of the fronds. Fio. 51. — Group of coal-formation ferns, a, Odontopteris suhcuneata (Bnu- bury). B, Neuropteria cordata (Brongniart). c, Alethopteris lonc/dtica (Brongrniart). d, Dicti/opteris obiiqud I Hunhury), e, Phyllopteris an- tiqua (Dawson), magnified; e>, Natural size, f, H'europteris cyclopte- roidea (Dawson). Of about eight families into which modern ferns are divided, seven are found in a fossil state, and of these, four at least, the Ci/aihacew, the OpMoglossecB, the Hy- THE CARBONIFEROUS FLORA. 127 FiQ. b2.—Alethopteri8 grandis (Dawson). Middle coal-formation of Nova Scotia. Fig. bZ.—Cyclopteris (Aneimites) Acadica CDawson), a tree-fern of the Lower Carboniferous, a, Pinnules. 6, Fragment of petiole, c, Re- maina of fertile pinnules. It I l! 1 (1 I : I 128 THE GEOLOGICAL HISTORY OP PLANTS. menophyllacecB, and the Marattiaccw, go back to the coal- formation.* Some of these ferns have the more complex kind of spore-case, with a jointed, elastic ring. It is to be ob- Fio. 54. — Sphenopteria latior, Dawson. Coal-formntion. a, Pinnule magnifled, with traces of fructiliuation. served, however, that those forms which have a simple spore-case, either netted or membranous, and without annulus, are most common in the Devonian and lowest Fio. 55. — Fructification of Paloeozoic ferns, a, Thecre of Archceopteris (Erian). 6, Theea of Setiftenbergia (CarboniferQus). c, Thecffi of Asterotheca (Carboniferous). Carboniferous. Some of the forms in these old rocks are somewhat difficult to place in the system. Of these, the * Mr. R. Kidston has recently described very interesting forms of fern fructification from the coal-formation of Great Britain, and much has been done by European palseobotanists, and also by Lesquereux and Fontaine in America. THE CARBONIFER(>DS FLORA. 129 Fio. 56. — Tree-ferns of the Carboniferous, a, MegapTiijton mnrfnificum, \ Dawson, restored, b, Leaf-scar of the same, two thirds natural size. V B' Row of leaf-sears, reduced, c, I'uLvopterU Ihrtii^ f^Q&xH h&M iiixi\x- ral size, d, Jiilceopteris Acadica^ scars half natural size, 18 t till " •i^ ; 130 THE GEOLOGICAL HISTORY OF PLANTS. allied to the gingko-trce of China species of Archmopteris, of the Upper and Middle Erian, are eminent as examples. This type, however, scarcely extends as high as the coal-formation.* Some of the tree-ferns of the Carboniferous present very remarkable features. One of these, of the genus Megaphyton, seems to have two rows of great leaves, one at each side of the stem, which was probably sustained by large bundles of aerial roots (Fig. 56). In the Carboniferous, as in the Erian, there are leaves which have been referred to ferns, but are subject to doubt, as possibly belonging to broad-leaved taxine trees One of these, repre- sented in Fig. 57, has been found in the coal-formation of Nova Scotia, and referred to the doubtful genus Nocggcrathia. Fontaine has proposed for simi- lar leaves found in Virginia the new generic name Saportca. Ferns, as might be inferred from their great age, are at the present time dispersed over the whole world ; but their head- qusirters, and the regions to wliich tree-ferns are confined, are the more moist climates of the tropics and of the southern hemisphere. The coal-swamps of the northern hemisphere seem to have excelled even these favoured regions of the j)resent world as a paradise for ferns. I have already stated that the Carboniferous consti- tutes the headquarters of the Coriaites (Fig. 58), of which a large uumber of species have been described, both in * The pretty little ferns of (.^ j genus Botryehium (moonwort), so common in American and European woods, seem to be their nearest mod- ern allies. Fio. 57. — Noeggerathia dispar (half nutiirul size). THE CARBONIFEROUS FLORA. 131 Europe and Arr/^rica. We sometimes, though rarely, find their stems showing structure. In this case we have a large cellular pith, often divided by horizontal parti- tions into flat chambers, and constituting the objects which, when detached, are called SternhergicB (Fig. G2). These Sternbergia j)iths, however, occur in true coni- fers as well, as they do in the modern world in some trees, like our common butternut, of higher type ; and I showed many years ago that the Sternbergia type may be detected in the young twigs of the balsam -fir {Abies balsamifera). The pith was surrounded by a ring of scalariform or barred tissue, often of considerable thickness, and in young stems so important as to have suggested lycopodia- ceous aflBnities. But as the stem grew in size, a regular ring of woody wedges, with tissue hav- ing rounded or hex- agonal pores or discs, like those of pines, was developed. Outside this was a bark, often apparently of some thickness. This struct- ure in many important points resembles that of cycada, and also approajiis to the structure of Sigillaria, while in its more higlily ac,?1opcd forms it approximates to that of the conifers. Fio. 58. — Cf^rdaiku ( Dor>/cordai(es), Grand' Eury, reduced. (1 r!i''i i: :;i i' I' N ill n H 132 THE GEOLOGICAL HISTORY OF PLANTS. On the stems so constructed were placed long and often broad many-nerved leaves, with rows of stomata or breathing-pores, and attached by somewhat broad bases to the stem and branches. The fruit consisted of racemes, or clusters of nutlets, which seem to have been provided Fio. 59. — Fruits of Cordaites and Taxine Conifers fcoal-forraation. Nova Scotia.) A, Antholithei^ nqunmoswi (two thirds), b, A. rliohaocurpi (two thirds). ]i>, Curpel restored, o, A. (t/iinoKiw (natural size). I), Trigonofarpum inttrnwilinm. e, T. JVonfrtjenit/iii. k, T. avdla- niim. o, Jihabdocnrpxis insiijnid, reduced, n, AntholUhes pijgma'us, I, Cardiomrpum fuitans. k, Cai'dincarpitm hi»ectiim. i., Sporangites papilluiay lycopoiliuceous macrosporoB (natural feize and raa;j;niflcd). THE CARBONIFEROUS FLORA. 133 M with broad lateral wings for flotation in the air, or in some cases with a pulpy envelope, which flattens into a film. There seem to have been structures of both these kinds, though in the state of preservation of these curious seeds it is extremely difficult to distinguish them. In the first case they must have been intended for dissemination by the wind, like the seeds of spruces. In the latter case they may have been disseminated like the fruits of taxine trees by the agency of animals, though what these were it would be difficult to guess. These trees had very great reproductive power, since they produced numerous seeds, not singly or a few together, as in modern yews, but in long spikes or catkins bearing many seeds (Fig. 59). It is to be observed that the Cordaites, or the Cor- daitincB, as they have been called, as a family,* constitute another of those intermediate groups with which we have already become familiar. On the one hand they approach closely to the broader-leaved yews like Gingko, Phyllo- cladus, and Podocarpus, and, on the other hand, they have affinities with Cycadaceae, and even with Sigillaria3. They were beautiful and symmetrical trees, adding some- tiiing to the variety of the rather monotonous Palaeo- zoic forests. They contributed also somewhat to the ac- cumulation of coal. I have found that some thin beds are almost entirely composed of their leaves, and the tissues of their wood are not infrequent in the mineral charcoal of the larger coal-seams. There is no evidence that their root« were of the stigmaroid type, thoui^h tlicy evidently grew in the same swampy flats with the Sigillaria3 and Calami tes. It may, perhaps, be well to say here tliat I believe there was a considerably wide range of organisation in the CordaitinjE as well as in the Calamites and Sigillarire, and that it will eventually be found that there were three lines W * Englcr ; Cordaitees of Renault. il il hi ; I tit III I'l |: I 134 7HE GEOLOGICAL HISTORY OF PLANTS. of connection between the higher cryptogams and the phaenogams, one leading from the lycopods by the Sigil- lariee, another leading by the Cordaites, and the third leading from the E(jaisetums by the Calami tes. Still further back the characters afterward separated in the club-mosses, mare's-tails, and ferns, were united in the Rhizocarps, or, as some now, but I think somewhat un- reasonably, prefer to call them, the " heterosporous Fili- cina3." In the more modern world, all the connecting links have become extinct and the phaenogams stand widely separated from the higher cryptogams. I do not make these remarks in a Darwinian sense, but merely to state what appear to be the lines of natural affinity and the links wanting to give unity to the system of nature. Of all the trees of the modern world, none are perhaps so widely distributed as the pines and their allies. On mountain-tops and within the Arctic zone, the last trees that can struggle against the unfavourable conditions of existence are the spruces and firs, and in the warm and moist islands of the tropics they seem equally at home with the tree-ferns and the palms. We have already seen that they are a very ancient family, and in the sandstones of the coal-formation their great truiiks are frequently found, infiltrated with calcareous or silicious matter, and still retaining their structure in the greatest perfection (Fig. 60). So far as we know, the foliage of some of them which constitutes the genera Walchia and Araucarites of some authors (Figs. 60, 63) was not dissimilar from that of modern yews and spruces, though there is reason to believe that some others had broad, fern-like leaves like those of the gingko. None of them, so far as yet cer- tainly known, were cone-bearing trees, their fruit having probably been similar to that of the yews (Fig. 61). The minute structures of their stems are nearer to those of the conifers of the islands of the southern hemisphere than to that of those in our northern climes — a cor- THE CARBONIFEROUS FLORA Fio. fiO. — Coniferous wood and t'orui>.'e (Carbonil'orouH). a, Aravcarifes grdcilis^ reduced. B, Dadoxi/loii Acndi'itium (radinl), 90 dimiiH. ; B' 0^"'>Kcntiul), 90 dianiH. ; b», cell showiiij^ areolation, 250 diams. c, Dalori/lon materinrinm (radinl), 90 diams. ; c' (tanx//lon tinti- qiiiiiK ^radial), 90 diams.; u* (tunguntiul), 90 diums. ; u", cell showing areolation, 260 diuuis. • ■ . - ■ u.. « 0*00,,* « « ,,■ O ■> ■ 5 0 J J 3 0 « > T^-7^ r i i y ; \ II p i I 136 THE GEOLOGICAL HISTORY OF PLANTS. relation, no doubt, to the equable climate of the period. There is not much evidence that they grew with the Si- gillariae in the true coal-swamps, though some specimens have been found in this association. It is more likely that they were in the main inland and upland trees, and B d Fig. 61. — Trigonocarpum Hooheri, Daw- son, from "the coal-measures of Cape Breton. Probably the fruit of a Tax- "' ine tree, a, Broken specimen magni- fied twice natural size, b, Section magnified : a, tiie testa ; ft, the teg- men; c, the nucleus; d, the embryo, c, Portion of the surface of the inner coat more highly magnified. ', ■■< that in consequence they are mostly known to us by drifted trunks borne by river inundations into the seas and estuaries. A remarkable fact in connection with them, and show- ing also the manner in which the most durable vegetable structures may perish by decay, is that, like the Cordaites, they had large piths with transverse partitions, a struct- THE CARBONIFEROUS FLORA. 137 uro which, as I have already mentioned, appears on a minute scale in the twigs of the fir-tree, and that some- times casts of these piths in sandstone appear in a separate form, constituting what have heen named Sternbcrgim or Artisiw. As Renault well remarks with reference to Cordaites, the existence of this chambered form of pith implies rai)id elongation of the stem, so that the Cordaites and conifers of the coal-formation were probabl}' quickly growing trees (Fig. 62). The same general statements may be made as to the coal-vegetation as in relation to that of the Erian. In '* *WWW„„ 't»lniftrilf'^ff}ftfttl' iilL.i; i'Mr' ';iiiHi",'i ,l;iJM|i |liill!|i,l| a a CL Fio. 62. — Sternhergia pith of Dadoxylon. a, Specimen (natural size), sliowinj; renmins of wood at a, «i^ Lyeopodiuni ('a4lIiBi'uN0&i'\j Peat (Vaux) Ca^IIwVVOio Brown coal (Sehrothcr) C24I1i4|',tO,oi''() , Lignite (Vaux) CaiHui'^irOniV I3i*uminous coal (Repnault) CaillioOai'o **It will be seen from tliis comparison that, in ulti- mate composition, cork and Lycopodium are nearer to lignite than to woody fibre, and may be converted into coal with far loss loss of carbon and hydrogen than the latter. They in fact ajjproach closer in composition to resins and fats than to wood, and, moreover, like tlioso substances repel water, with which they are not easily moistened, and thus ai ~ able to resist those atmospheric influences which effect tlie decay of woody tissue." I would add to this only one further consideration. The nitrogen present in the Lycopodium s{)()res, no doubt, belongs to the protoplasm contained in tliem, a substance which would soon perish by decay ; and subtracting this, the cell-walls of the spores and the walls of the sporc- ♦ " Canadian Naturalist," vi., 253. TUE CARBONIFEIIOUS FLORA. 145 cases would be most suitable material for the production of bituminous coal. But this suitableness they share with the epidermal tissue of the scales of strobiles, and of the stems and leaves of ferns and lycopods, and, above all, with the thick, corky envelope of the stems of Siyillarim and similar trees, which, as I have elsewhere shown,* from its condition in the prostrate and erect trunks con- tained in the beds associated with coal, must have been highly carbonaceous and extremely enduring and im- permeable to water. In short, if, instead of ** spore-cases," we read ** epidermal tissues in general, including spore- cases," all that has been affirmed regarding the latter will be strictly and literally true, and in accordance with the chemical composition, microscopical characters, and mode of occurrence of coal. It will also be in accordance with the following statement, from my paper on the "Struct- ures in Coal," published in 1859 : "A single trunk of Sigillaria in an erect forest pre- sents an epitome of a coal-seam. Its roots represent the Stigmaria underclay ; its bark the compact coal ; its woody axis the mineral charcoal ; its fallen leaves (and fruits), with remains of herbaceous plants growing in its shade, mixed with a little oarthy matter, the layers of coarse coal. The condition of the durable outer bark of erect trees concurs with the chemical theory of coal, in showing the especial suitableness of this kind of tissue for the production of the purer compact coals. It is also probable that the comparative impermeability of the bark to mineral infiltration is of importance in this respect, enabling this material to remain unaffected by causes which have filled those layers, consisting of herbaceous materials and decayed wood, with pyrites and other min- eral substances." * " Vegetable Rtructiires in Coal," " Journal of Geological Society," , 026. " Conditions of Accuroulation of Coal," ibid.^ xxii., 96. " Aca- XV, dian Geology," 197, 404. I! !i I I \ i: ! i ! I .'I i'l Y 111'' 146 THE GEOLOGICAL HISTORY OF PLANTS. We need not go far in search of the uses of the coal vegetation, when we consider the fact that the greatest civilised nations are dependent on it for their fuel. With- out the coal of the Carboniferous period and the iron -ore which is one of the secondary consequences of coal ac- cumulation, just as bog-ores of iron occur in the subsoils of modern peats, it would have been impossible either to sustain great nations in comfort in the colder climates of the northern hemisphere or to carry on our arts and manufactures. The coal-formation yields to Great Brit- ian alone about one hundred and sixty million tons of coal annually, and the miners of the United States ex- tract mainly from the Fame formation nearly a hundred million tons, while the British colonies and dependen- cies produce about five million tons ; and it is a re- markable fact that it is to the English race that the greatest supply of this buried power and heat and li^ht has been given. The grea forests of the coal period, while purifying the atmosphere of its excess of unwholesome carbonic acid, were storing up the light and heat of Palaeozoic summers in a form in which they could be recovered in our human age, so that, independently of their uses to the animals which were their contemporaries, they are indis- pensable to the existence of civilised man. Nor can we hope soon to be able to dispense with the services of this accumulated store of fuel. The forests oi to-day are altogether insufficient for the supply of our wants, and though we are beginning to apply water-power to the production of electricity, and though some promis- ing plans have been devised for the utilisation of the direct heat and light of the sun, we are still quite as de- pendent as any of our predecessors on what has been done for us in the Palaeozoic age. In the pr'""'ous pages I have said little respecting the physical gr. ^raphy of the Carboniferous age ; but, as may :n! H THE CARBONIFEROUS FLORA. 147 m be inferred from the vegetation, this in the northern hemisphere presented a greater expanse of swampy flats little elevated above the sea than we find in any other pe- riod. As to the southern hemisphere, less is known, but the conditions of vegetation would seem to have been es- sentially the same. Taking the southern hemisphere as a whole, I have not seen any evidence of a Lower Devonian or Upper Si- lurian flora ; but in South Africa and Australia there are remains of Upper Devonian or Lower Carboniferous plants. These were succeeded by a remarkable Upper Carboniferous or Permian group, which spread itself all over India, Australia, and South Africa,* and contains some forms (Vertcbraria, Phyllotheca, Glossoplcris, &c.) not found in rocks of similar age in the northern hemi- sphere, so that, if the age of these bods has been correctly determined, the southern hemis})liere was in advance in relation to some genera of plants. This, however, is to be expected when we consider that the Triassic and Ju- rassic flora of the north contains or consists of intruders from more southern sites. These beds are succeeded in India by others holding cycads, &c., of Upper Jurassic or Lower Cretaceous types (Rajmahal and Jabalpur groups). Blanford has shown that there is a very great similar- ity in this series all over the Australian and I'ldian re- gion, f Ilartt and Darby have in like manner distin- guished Devonian and Carboniferous forms in Brazil akin to those of the northern hemisphere. Thus the southern hemisphere would seem to have kept pace with the north- ern, and according to Blanford there is evidence there of cold conditions in the Permian, separating the Palceozoic i."- * Wyley, "Journal Geol. Society," vol. xxiii., p. 1'72; Daintree, ibid., vol. xxviii. ; also Clarke and McCoy. f " Journal Geol. Society," vol. xxxL !i|! i' 148 THE GEOLOGICAL HISTORY OF PLANTS. flora from that of the Mesozoic, in the same manner that Ramsay has supposed a similar period of cold to have done north of the equator. This would imply a very great change of climate, since we have evidence of the exten- sion of the Lower Carboniferous flora at least as far north as Spitzbergen. The upper coal-formation we cannot, however, trace nearly so far north ; so that a gradual refrigeration may have been going on before the Permian. Thus in both hemispheres there was a general similarity in the later Palaeozoic flora, and per- haps similar conditions leading to its extinction and to its replacement by that to be described in the next chapter. - NOTES TO CHAPTER IV. \'-i i< i 1. I. Characters and Classification of Palaeozoic Plants. In the space available in tV- work it would be impossible to enter fully into the classifleation L Palaeozoic plants; but it may be well to notice s'^me important points for the guidance of those who may desire to collect specimens; more especially as much uncer- tainty exists as to affinities and very contradictory statements are made. The statements below may be regarded as the results of actual observation and of the study of specimens in situ in the rocks, as well as in the cabinet and under the microscope. Gymnosperme^. Family Conifer.e; Genua Dadoxylon, Endlicher; Araucarites, Goeppert ; Araucarioxylon, Kraus. The trunks of this genus occur from the Middle Devonian to the Permian inclusive, as drift-logs calcified, silicified, or pyritised. The only foliage associated with them is of the type of Walchia and Araucarites — viz., slender branches with numerous small spiral acicu- lar leaves. Two of the coal-formation species, D. materianim and another, had foliage of this type. That of the others is unknown. They are all distinct from the wood of Cordaites, for which see under that genus. THE CARBONIFEROUS FLORA. 149 The following are North American species: Trunks. Dadoxylon Ouangondianum, Dn . .M. Erian Report, 1871.* n.IIalti, Dn " D. Neivherryi, Dn " " Report, 1882. Acadian Geol- ogy. 1). Clarkii, Dn. (Cordicoxylon ?) . . . " D. Acadianum, Dn Coal - formation ; ^ and millstone grit. D. Maleriarum, Dn Do. and Pernio- " Carb. Z>. (Palajoxylon) antiquius, Dn . . .L. Carboniferous. " D. annxilatum, Dn Coal-formation. " Orrnoxylon Erianum, Dn Erian Report, 1871. Foliage. Arancarites gracilis, Dn N. Coal-formation " and Permian. Walchia robusfa, Dn.. W. imbricatula, Dn.. . Permian. Report on Prince Ed- ward Island. All of the above can be vouclied for as good species ba«!ed xipon microscopic examination of a very large number of trunks from dif- ferent parts of North America. The three Erian species of Dadoxylon and D. antiquius from the Lower Carlxmiferous have two or more rows of cells in the medullary rays. The last named has several rows, and is a true Palo'oxylon allied to D. Withami of Great Britain. 1). maferiarium is specially characteristic of the upper coal-formation and Permian, and to it must belong one or both of the species of foliage indicated above. D. Clarkii has very short, simple medullary rays of only a few cells superimposed, and has an inner cylinder of sculariform vessels, approaching in these jioints to Cordaites. Orrnoxylon has a very peculiar articulated pith and simple medullary rays. Witham in 1838 described several Carboniferous species of pine- wood, under the generic name Pinites, separating under the name Pitus species which appeared to have the discs on the cell-walls * " Geological Survey of Canada : Fossil Plants of Erian and Upper Silurian Formations," by J. W. DaNvson. IT w^ 150 THE GEOLOGICAL HISTORY OF PLANTS. i; •*- ! 8i^ separate and in transverse lines. Witham's name was changed by Goeppert to Araucarites, to indicate the similarity of these woods to Araucaria, Pinites being reserved for trees more closely allied to the ordinary pines. Endlicher, restricting Araucarites to foliage, etc., of Araiicaria-like trees, gave the name Dadoxylon to the wood ; and this, through Unger's " Genera and Species," has gained somewhat general acceptance. Endlicher also gave the name Pissadendron to the species which Witham had called Pitua; but Brongniart pro- posed the name Palmoxylon to include all the species with thick and complex medullary rays, whatever the arrangement of the discs. In Schimper's new work Kraus substitutes Araucarioxylon for End- licher's Dadoxylon, and includes under Pissadendron all the species placed by Brongniart in Palceoxylon. To understand all this confusion, it may bo observed that the characters available in the determination of Palaeozoic coniferous wood are chiefly the form and arrangement of the wood-cells, the character of the bordered pores or discs of their walls, and the form and composition of the medullary rays. The character on which Witham separated his genus Pitus from Pinites is, as I have ascertained by examination of slices of one of his original specimens kindly presented to me by Mr. Sanderson, of Edinburgh, dependent on state of preservation, the imperfectly pre- served discs or areolations of the walls of the fibre presenting the appearance of separate and distinct circles, while in other parts of the same specimens these discs are seen to be contiguous and to as- sume hexagonal forms, so that in this respect they do not really differ from the ordinary species of Dadoxylon. The true character for subdividing those species which are especially characteristic of the Carboniferous, is the composite structure of the medullary rays, which are thick and composed of several radial piles of cells placed side by side. This was the character employed by Brongniart in separating the genus Palo'oxylon, though he might with convenience have retained Witham's name, merely transferring to the genus the species of Witham's Ignites which have complex medullary rays. The Erian rocks present the greatest variety of types, and Palceoxylon is especially characteristic of the Lower Carboniferous, while species of Dadoxylon with two rows of bordered pores and simple medullary rays are especially plentiful in the upper coal-formation and Permo- Carboniferous. The following table will clearly show the distinctive characters and relations of the genera in question, as held by the several authors above referred to : / . , . * , ■■■■ ■•! THE CARBONIFEROUS FLORA. 151 Wood of Palaozoic Conifers. Woody fibres. Medullary rayiuid pitb. Generic ntmei. Geological age. No discs. One or two series of cells. Aporoxylon, Unger. Devonian (Erian). Complex, or of two or more series of cells. Pith Sternbergian. r PituK, Witham. PalcEoxylon, Brongni- -( art. Pinsndendron, End- t licher. Middle and Lower Car- boniferous and Devo- nian. Discs in one se- ries contigu- ous, or in sev- eral series Simple, or of one row of cells. Pith Sternbergian. Araucaritea, Goeppert Dadoxylon, Endhcner. Arancarioxylon, . Schimper. Ormoxylon* Dn. Upper CartK>- niferous and Permian. spirally ar- ranged. Pith in spherical chambers. Devonian. Medullary sheath sealariform. Medullary rays frequeut, simple, short. Dadoxylon (Cordaoxy- lon),+ Dn. Devonian. ♦ Type O. Erianum, Dn., " Report on Canadian Plants." 1871. t Type D. Clarkii, Dn., " Report on Canadian Plants," 1882. This may be wood of Cordaites, to which it approaches very closely. Family Coedaite^e, Genus Cordaites, Brongniart. Trunks marked by transverse scars of attachment of bases of leaves ; leaves broad, with many parallel veins, and attached by a broad base ; pistillate and staminate catkins of the nature of An- tholithes. Fruit winged or pulpy, of the kind known as Cardio- carpum. Stem with a Sternbergia pith, usually large, surrounded by a ring of pseudo-sealariform vessels, and with a cylinder usually narrow, of woody wedges, with bordered pores in one or more series, and with simple medullary rays. From specimens kindly presented to me by Prof. Renault, I have been able to ascertain that the stems of some at least of these plants (Eucordaites) are distinct in structure from all the species of Dadoxylon, above mentioned, except D, Clarkii, of the Erian. They may be regarded as intermediate between those of conifers and cycads, which is indeed the probable position of these remarkable plants. Grand Eury has divided the Cordaites into sub-genera, as fol- lows: 1. Eucordaites. — Leaves spatulate, obovate, elliptical, or Ian- 152 TUE GEOLOGICAL HISTORY OF PLANTS. i i' !l I: * ! ['■ - h -i- ceolate, sessile, entire, with rounded apices and of leathery con- sistency. The leaves urc from twenty to ninety centimetres in length. The nerves are either equally or unequally strong. 2. Dorycordaites. — Leaves lanceolate, with sharp points ; nerves numerous, fine, and equal in strength. The leaves attain a length of from forty to fifty centimetres. 3. Poacordaites. — Leaves narrow, linear, entire, lilunt at the point, with nerves nearly equally strong. The leaves are as much as forty centimetres in length. To these Renault and Zeiller have added a fourth group, Scuto- cordaites. Oeyius Sternbeegia. This is merely a provisional genus intended to receive casts of the pith cylinders of various fossil trees. Their special peculiarity is *^hat, as in the modern Cccropia peltata, and some species of Ficus, * • pith consists of transverse dense partitions which, on the elonga- tion of the internodes, become separated from each other, so as to produce a chambered pith cavity, the cast of which shows transverse furrows. The young twigs of the modern Abies hahamifera pre- sent a similar structure on a minute scale. I have ascertained and described such pith-cylinders in large stems of Dadoxylon Oxiangon- dianum, and D. materiarium. They occur also in the stems of Cordaites and probably of Sigillarim. I have discussed these curi- ous fossils at length in " Acadian Geology " and in the " Journal of the Geological Society of London," 1860. The following summary is from the last-mentioned paper : j a. As Prof. Williamson and the writer have shown, many of the Sternhergia piths belong to coniferous trees of the genus Da- doxylon. b. A few specimens present multiporons tissue, of the type of Didyoxylon, a plant of unknown afiinities, and which, according to Williamson, has a Sternbergia pith. c. Other examples show a true sealariform tissue, comparable with that of Lepidodendron or Sigillaria, but of finer texture. Corda has shown that plants of the type of the former genus (his Loma- tophloios) had Ster7ibergia piths. Some plants of this group are by external characters loosely reckoned by botanists as ribless Sigillarm {Clathraria)', but I believe that they are not related even ordinal ly to that genus. ' d. Many Carboniferous Stemhergim show structures identical with those described above as occurring in Cordaites, and also in some of the trees ordinarily reckoned as Sigillarim. \ li THE CARBONIFEROUS FLORA. 153 Oenua Cardiocarpum. 1 have found at least eight species of these fruits in the Erian and Carboniferous of New Brunswick and Nova Scotia, all of which are evidently fruits of gymnospermous trees. They agree in hav- ing a dense coaly nucleus of appreciable thickness, even in the flattened specimens, and surrounded by a thin and veinless wing or margin. They have thus precisely the appearance of samaras of many existing forest-trees, some of which they also resend)le in the outline of the margin, except that the wings of samaras are usually veiny. The character of the nucleus, and the occasional appearance in it of marks possibly representing cotyledons or embryos, forbids the supposition that they are spore-cases. They must have been fruits of phtpnogams. Whether they were winged fruits or seeds, or fruits with a pulpy envelope like those of cycads and some conifers, may be considered less certain. The not infrequent dis- tortion of the margin is an argument in favour of the latter view, though this may also be supposed to have occurred in samaras par- tially decayed. On the other hand, their being always apparently flattened in one plane, and the nucleus being seldom, if ever, found denuded of its margin, are arguments in favour of their having been winged nutlets or seeds. Until recently I had regarded the latter view as more probable, and so stated the matter in the second edi- tion of " Acadian Geology." I have, however, lately arrived at the conclusion that the Cardiocarpa of the type of C. cornutum were gymnospermous seeds, having two cotyledons embedded in an albu- men and covered with a strong membranous or woody tegmen sur- rounded by a fleshy outer coat, and that the notch at the apex rep- resents the foramen or micropyle of the ovule. The structure was indeed very similar to that of the seeds of Taxus and of SaUf'.i 158 TUE GEOLOGICAL HISTORY OF PLANTS. cularscar, and situated in verticils at the top of well-marked no leg of thi; 'iin. In trcc-fcrns the leaf-bases are largo and usually withou„ a dis- tinct articulating surf»«ie. The vascular l)undles are numerous. Protopteris has round(!d leaf-scars with a large hf)rseshoc- haped bundle of vessels above and sniuU bundles l)olow. Oaulopteris has large elliptic or oval leaf-scars with vascular scars disposed con- centrically. Pal^opteris,* of Geinitz, has the leaf-scars transversely oval and the vascular bundles confluent in a transverse band with an appendage or outlying bundle below. Stemmatopteris has leaf- scars similar to those oi Cauloptcris, but the vascular bundles united into a horseshoe-shaped band. 2. Subdii'iHion of Sicjillarim in Accordance with their Marldngs. The following groups maybe defined in this way; but, being based on one cluiracter only, they are of course in all probability far from natural : ' ■ 1. Siyillarin, Brongniart. Type, Sigillaria reniformis, Bron- gnijirt, or S. lirounii, Dawson. — Stem with broad ribs, usually mtu'h broader than the usually oval or elliptical tripunctate areoles, but disappearing at base, owing to expansion of the stem. Leaves nar- row, long, three-nerved. 2. RhytidolcpiH, Sternberg. Type, S. scuMlnta, Brongniart. — Ribs narrow, and often transversely striate. Areoles large, hexag- onal or shield-shaped, tripunctate. Leaves as in last group. Rings of rounded scars on the stems and branches mark attachment of fruit. It is i)ossibIe that some of the smaller stems of this group niay be branches of trees of group first. 3. Syrinjiodendron, Sternberg. Type, S. organnm, L. and IT., S. oculala, Brongniart.. — Stems r* ' -^d ; areol»>s small and round, and apparently with a single scar, ,, three closely approximated. These are rare, and lial)l(! to l)e confounded with decorticated ex- amines of other groups ; l)ut I have some specimens which unques- tionably represent the external surface. 4. Fdi'ulnria, Sternberg. Type. Sigillaria chgnns of Brongni- art.— Leaf-bases hexagonal, or in young branches elliptical, in vertical rows, but without distinct ribs, except in old or decor* icated stems. Fruit borne in verticils on the nranSV/yi7- lariiB, but of Lepidodetidra and ( 'alamodendra as W(!ll. (-'onfining myself to my own observations, three types of Siffillanai are known to me l)y their internal structures, though I cannot certainly corre- late all of these with the exter.ial markings referred to above. 1. Diplnxylon, in which the stem consists of a snuUl internal axis surrounded by a very thick inner bark and a dcmse outer cortex. A fine example from the South Joggins is thus described : * "The axis of the stem is about six centimetres in its greatest diameter, and consists of a central pith-cylinder and two concen- tric coats of scalariform tissue. The pith-cylinth^r is replaced by sandstone, and is about one centimetre in diameter. The inner cyliiuh^r of scalarifortn tissue is perfectly continuous, not radiated, and about one millimetn! in thickness. Its vessels arc somewhat crushed, but have liecn of large diameter. Its outer surface, which readily separates from that of the outer cylinder, is striated longi- tut"; lal'y. The outer cylinder, which institutes by much the largest part of the whole, is also compose(l of scalariform tissue; but thin is radially arranginl, with the individual cells (juaTi all the sides and usually simple and straight, but sometimes l)ranching or slightly reticulated. The wall intervening between the bars has extremely delicate longitviclinal waving lines of ligneous lining, in th(! manner first described by Williamson as occurring in the scalariform tissue of certain Lepidodendra. A few small radiating spaces, partially • " Journal of the Geological Society of London," Novciuber, '7. 1 I I ' ,i lil I r : IGO THE GEOLOGICAL HISTORY OF PLANTS. occupied witli pyrites, obscurely represent the medullary rays, which must have l»cen very feebly developed. 'J'ho radiating bundles passing to the leaves run nearly horizontally ; but their structure is very imrcrfecttly jjreserved. 'J'ho stem Ijeing old and probably long deprived of its leaves, they may have been partially disorganised before, it was fossilised. TIk; outer surface of th(! axis is slriaU'd longitudiiuilly, and in some places marked with imfircssions of tort- uous libres, apf)ar(!ntly those of the inner bark, in the cross-sec- tion, where weathered, it shows concentric rings; but under the mi(!roscop(! thes(! ai)p<'ar rather as bands of compressed tissue than as proper lines of growth. They are alxjut twenty in iiumlM'r. This tree has an erect, ribbed trunk, twelve feet in height and fifteen inches in diameter, swc^lling to about two feet at the base. 2. Fdi'iilurid 'J'ypc. — This has been well described by Urongniart and by Renault,* and dilTers from the above chiefly in the; fact that the outer exogenous woody zoiu; is comi)os('d of reticulatc.'d instead of scalariform li-.iue, and the inner /one is of the peculiar form which 1 have (iharacterised as pseudo-scalariform. 8. Siyillaria l*ropcr. — This I have, illustrated in my paper in the "Journal of the Geological Society" for May, 1H71, and it ap- peal's to repnist^nt the highest and most perfect type of the larger riblied Sujillarin. 1'his structure; I have; (les(;ribed as follows, bas- ing my descrij)t ion on a very lim; axis found in an erect stem, and on the fragments of the woody axis found in the bases of other erect stems : a. A dense ct ''...lar outer bark, usually in the slate of compact coal — but wh( II its structure is preserved, showing a tiH.sue of thick- ened parenchymatous cells. • h. A very thick inner bark, which has iismilly in great part perished, or been converted into (!oal, but which, in old trunks, con- tained a large; <|uantity of prosenehymatous tissue, very tough and of great durability. This "bast-tissue" is comparable with that of the inner bark of modern conifers, and constitutes much of tiie min- eral charcoal of the coal-seams, c. An outer ligneous cylinder, composed of wood-cells, (lither with a single row of larg(! bordered [)ores,f in the numtier of pines * "Uotani(pie Fossile," Paris, 1881. f These are the same with the wood-cells elsewhere called diHcigorouB tissue, and to which I have applied the terms unipoious and multiporoua. The markings on the walls are caused by an unlincd p ,.tion of the cell- wall placed in a disk or depression, and this often surrounded by an THE CARBONIFEROUS FLORA, ir,i and cycads, or with two, three, or four rows of siioh pores sometimes inscribed in hexagonal areoles in the manner of Mu/orv/ora, This woody cylinder is traversed \>y medullary rays, which tire short, and composed of f(!W rows of ca-Ws su[U'riinposed. It is also traversed by ol)li(pio radiating bundles of pseudo-sealariform tissue proceeding to the leaves. In soiu(! Sit/if/nrun this outer cylinder was iiself in part com[)osed of pscudo-sciilariform tissue, as in Jirongniart's specimen of .S'. elcf/aiiM ; and in others its plucc; may have l)een taken by mul- tiporous tissue, as iti a case alK)ve n^ferred to ; but I have no reason to Ixdieve that either of these variations occurred in the typical ribbed sjiecic^s now in question. Tfie woody filires of the outer cylinder nuiy b(? distinguished most readily from tliosi; of conifers, as already mentioncid, by the thinness of their walls, and the more irregular distribution of the pores. Additional charact(!rs are fur- nished by the nietlidlary rays and the radiating bundles of 8calari- form tissues when these can be observed. d. An innifr cylinder of ps(!udo-scalariform tissue, I have adopted the term ftseudo-scidariform for this tissue, from the con- viction that it is not liortiologous with the scalar! fffrri' ducts of ferns and other acrogi'iis, but that it is merely a modification of tin; dis- c ,gerf)us wood-cells, wit h pores elongated t ransversely, and sonuitimes separated by thic^kened bars, corres{)onding to the hexagonal areo- lation of the ordinary wood-cells. A similar tissut; exists in cycads, and is a substitutt; for the spiral vcssc^ls existing in (ordinary ex- ogens. e. A large medulla, or pith, consisting of a hollow cylinder of cellular tissue, from which proceed numc^rous thin diaphragms to- wards the cent Hi of the stem. These structures of the highest type of Sigillaria are on the one hand scarcely advanced b(!yond those of (JalninnpHun, as de- scribed by Williamson, and on the other a[)proach to those of (jordaitPH, as seen in specimens presented to mr- by Renault. Finally, as to the fruit of JSir/illarid', I Imvo no new facts to ofT(!r. The strobiles or sjiikes associated with these trees have Ijcen variously described as gymno.^permous (]((;nault) or cryptogamous ((loldenberg and Williamson). I have never seen them in plaoe. Two considerations, however, have always weighetl with me in refer- ence to this subj(!ct. One is the constant abundance of Trigotiocarpa hexagonal rim of thickenod wall ; but in all cases these Htnicturcs arc less pionoimeed than in I)tiilori//i>n, and less regidar in tlie walls of the liuiiie ceil, aa well us in dilTcrcnt layers of the tiesucs of the axia. !i tl '! r; 1. 1 M !! li ' ''■:■ n I; i" 1C2 THE GEOLOGICAL HISTORY OF PLANTS. and Cardiocarpa in the soil of the Sigillaria forests, as I have st»idied this at the South Jogj^ins. The other is that the rings of fruit-scars on the branches of Sigillaria are homologous with leaf-soars, not •with branches, and therefore should have borne single carpels and not cones or spikes of infloresceiice. These ai"e merely suggestions, lit I have no doubt they will be vindicated by future discoveries, which will, I have no doubt, show that in the family SigillariacecB we have really two families, one possibly of gymnospermous rank, or at least approaching to this, the other allied to the Lepidodendra. Cryptooamia. {Acrogenes.) Family Lepidodendrkte ; Oenua Lepidodexdron, Sternberg. These arc arboreal Lycopods having linear one-nerved leaves, stems branching dichotoiiiously, and with ovate or rhombic leaf-bases bearing rhombic leaf-scars, often very prominent. The fiuit is in scaly strol)iles, terminal or lateral, and there are usually, if not always, macrospores and microspores in each strobile. The young branches and stems have a central pith, a cylinder of scalariform tubes sending out ascending bundles to the leaves through a thick cellular and fibrous inner bark, and externally a dense cortex conflu- ent with or consisting of the leaf-bases. Older stems have a second or outer layer of scalariform fil)res in wedges with medullary rays, and strengthening the stem l)y a true c oogenous growth, much as in the Diploxylon typo of Sigillaria. The development of this exogenous cylinder is different in amount and rate in different species.* This different development of the exogenous axis is accompanied with appropriate external appearances in the stems, and the changes which take place in tlieir nuirkings. These are of three kinds. In some species the areoles, at first close together, become, in the pro- cess of the expansion of the stem, separated by intervening spaces of bark in a perfectly regular matmer ; so that in old stems, while widely separated, they still retain tlieir arrangement, while in young stems they are (piite close to one another. This is the case in L. corruga- tum. In other species the leaf-scars or bases increase in size hi the c'd stems, still retaining their forms an. uiululatum, and generally in those Lt'2,^dudtndra which have large leaf-bases. In these species the * See " Memoirs of Dr. Williamson," in " Philosophical TranHactlons," for ample details. THE CARBONIFEROUS FLORA. 163 continued vitality of the bark is shown by the occasional production of lateral strobiles on large branches, in the manner of the modem red pine of America. In other species the arcoles neither increase in size nor become regularly separated by growth of the intervening bark ; but in old stems the bark splits into deep furrows, between which may bo seen portions of bark still retaining the areoles in their original dimensions and arrangement. This is the case with Jj. Pictopn.ie. This cracking of the bark no doubt occurs in very old trunks of the first two types, but not at all to the same extent. As a type of Lepidodendron, 1 may describe one of the oldest Carboniferous species characteristic of the Lower Carboniferous in America, and corresponding to L. Ydtheimianum of Kurope. LEPrDODE>fDRON CoRRuoATUM, Dawson. — (See Fig, 4:5, snjrrn.) " Quarterly Journal of Geological Society," vol. xv. ; " Acadian Geol- ogy," page 451. Habit of Orowth. — Somewhat slender, with long V)ranches and long, slender leaves having a tendency to become horizontal or drooping. Markings of Stem. — Leaf-bases disposed in quincunx or spirally, elongate, ovate, acute at both ends, l)Ut more acute and slightly oblique at the lower end ; most prominent in the iq)per third, and with a slight vertical ridge. Leaf-scars small, rounded, and showing only a single punctiforin vascular scar. The leaf-scar on the outer surface is in the \q)per third of the base; but the obliquity of the vascular bundle causes it to be nearly central on the inside of the epidermis. In young succulent shoots the leaf-scars are contiguous and round as in Cyclostigma, without distinct leaf-bases. In this state it closely resembles L. Olivieri, Kichwald.* In the ordiiuiry yoimg branches the leaf-si ars are contiguous, and closely resemble those of L. ehgann, IJrongt. (Fig. 43 C). As the branches increase in diameter the leaf-scars slightly enlarge and sometimes assume a vcrticillate appearance (Fig. 413 D). As they still furtluir enlarge they become scpiinittMl by gradually increasing spaces of bark, marked with many waving stritc or wrinkles (Fig. 43 I, N). At the base of old stems the bark assumes a gfjni'rally wrinkled appearance without distinct scars. Kiwrria or Decorticated States. — Of these there is a great variety, depending on the state of preservation, and the particular longi- tudinal ridges. Fig. 43 I) shows a form in which the vascular bun- dles appear as cylindrical truncate projecti'-ns. Other forms show * Lethaea Rossica, Plato Y, Figs. 12, 18. ^ 'rW I M Mil I; it ■rH ' ' 1 , 1 i j 1 i '• 1(U THE (iEOLOGICAL HISTORY OF PLANTS. tho loaf-hasPH promiiicni, or liave un a|)pfiarance of longitudinal rib- bin;^ prodiicMMl hy Mh! t!X|)aiisiori of tho bark. HlrurAure of Stem. — This is not porfnctly prcscrvod in any of my Hix'ciinctiH, l)iit oni; flattciu'd .sp((c-iinon .shows a central medulla with a iijirrow ring of scalariform vtisscils surrounding it, and consti- tuting the woody axis. The structure is thus siniilar to that of L. Jlarcourtii, which I regard as i)rol)ably tho same with tho closely allifid lititfi(l ut erxls, on- liirfxirig with growth <>! aU'in. Lwif-scurs contrul, rhornhic, trans- vor,s«. LenvpH. — Orift-rKTvcd, ntnitcly pointed, from four inchos in hiiigth on tlif! iarj^cr hrancJics to one inch or less on thf; braruihict.s. FnirlificalioH, — C'orutH larf^e. cyiindrifal or lon^ oval, with larp^o Hcales of tri^^onal form, and not (!lf)nKat('d but iyiii;? <;1ok(! to the sur- face. IJornc on lateral, slendtT hranchlets, with Hhort leaves. OenuH Iji:i'inoi'iii,oio.s, StcrnbiTi,'; ri.oiiKNUKoN, L, and II.; LoMAToi'Hi.o/os, (.'ordu. LcpidophloioH. — Under this gciiuirifj name, established by Stern- berg^, I include those Ivcojjodiaceous trees of the coal-measures which hav(! thick branches, transvcirsely e!on{,'at(!(l leaf-scars, eiu;h with three vascular j)oints and phuied on elevated or scale-like pro- tulM!ratices, long on»!-nerv(!d leaves, and larfje lateral strol)il(;s in vc^r- tloal rows or spirally disposed. Tlu-'ir strur/ture reseirdiles that of Lfpidwictidron, consisting? of a Sli'rnbcrfjid pith, a slemler axis of large scalariforrn vessels, giving off from its surfac*; biiiidh^s of smaller vesscsls to the leaves, a very thi<:k c<'llular bark, atid a thin dense outp«r I>art. TlicHr llattened bari< is frefjuent in the coal-beds and their roofs, airordiri}^ a thin hiycT of i)ure inj,' and transverse nodal constrictions. In study- ing' these plants in m'tu in the erect Calamite brakes of the coal- foririation of Nova Scotia, one soon becomes familiar with these ap- pearances, but th(!y are evidently unknown to the majority of palajo- botanists, though described in detail more than twenty years ago. When th(! outer surfa(;e is preserved it is sometinu's seen to bear vcrti(;ils of iutig nee(ll(!-lik(! leaves (C. (Jift/ii), or of branchlets with secondary whorls of similar leaves {(J. Suclcovii and C. rmdidatuH), No ('alamito known to mo bears broad one-nerved leaves like those of Aiit''rop/n///i/t'fi iiiul Annuhirid, though the larger stems of these plants have been described as Calauiitcs, and the term ('alftmoclatlus has been used to includt; both groups. The base of the ('alamito stem usually tcrminat(!S in a blunt point, and may be attached to a rhizome, or sevc^ral steins may bud out from each other in a group or stool. Tho roots are long and cylindrical, sometimes branching. The fruit consists of spikes of spore-cases, borne in whorls and sub- t(!nded by linear floral leaves. To these strobiles tho name Calamo- stachys has been given. Williamson has shown that the stem of Calamitcs consists of a central pith or cavity of large size surroutided by a cylinder con- sisting of alternato wedges ot woody and cellular matter, with ver- tical canals at the iimer sides of tlu; wedges, and slender medullary rays. The thick cellular wedges intervening between the woody wedges he calls [irimary medullary rays; the smaller medullary rays in the wedges, secondary medullary rays. There is thus a highly complex exogenous stem based on the same principle with the stem of a common Equiadum, but with much greater strength and complexity. Williamson has also shown that there are different sub-tyi)es of these stems. More especially he refers to the three following: 108 THE (JEOLOfJICAL IIISTonY OF PLANTS. i I !i inn I I ii:- .: ii Hr \-j (a) Cnlamites proper, which lias tho woody wos of soalari- form or Imrred tiH.sii« with Uiin nicduliiiry ruyH, and the thick pri- mary incchillary ruy.s arc c(;ihihir. (/i) <'(U(imo])ilHH hiin reticulated or rniilliporouH tJHsiio in tlio woody wedges with medullary rays, and tlic primary mciduilary wed^oH are (;omiK»8(!«l tho highest tyfw of calamitean stem. F would also add that under a and h there are some species in which the woody cylinder is very thin in com[)arison to the size of the stem. In c and d the woody cylinder is thick and massive, and the stems are often large and nodose. As an example of an ordinary C'alamite in which the external surface and foliat,'e arc [)reservcd, I iruiy (piotc the following from my report on the " l''l(jra of the Jjower Carboniferous antl Millstone Grit," 1H7:{: Calamitks IT.vniiLATUs, Brongniart. — This species is stated by Brongniart to ))e distinguished from Ww ('. Snr.lcovii, the character- istic ('alamite of the middle coal-formation, by its undulated ribs marked with fieculiar cellular reticulation. He suggests that it may be merely a varirdy of 6'. Sur.kovii, an opinion in which Schimper coincides; ])ut since I have received large additif)nal collections from Mr. Elder, containing not only the stems and branches, but also tho leaves and rhizomes, I am constrained to regard it as a distinct thougli closely allied species. The rhizomata anf slender, being from one to two inches in diameter, and jierftfctly flattencid. 'i'hey an: beautifully covered with u cellular niticulation on tlu; thin Imrk, and shf)W occasiomil round areoles marking the points of (ixit of the rootlets. I have long Ijeen familiar with irregular flattened st(!ms thus reticulate, ))ut have only recently been able to connect them with this species of C'alamite. The nuiin stems present a very thin carlKiiiateous bark reticu- lated like th(! rhizomes. They hav(! flat, broad ribs sej)arated by deep *" Quarterly Journal of the Geological Society," 1871. THE CARUOXIFKIiOUS FLORA. 109 and narrow furrows and utKluliitcd in a rcmarkahln mannfr oven when lilt' HtciiiHure Jliitt«'iH'gy, which, though they have Ixien treated by some Ijotanists as merely restorations, are in reality rej)resetilations of facts a<;tiially observed. On these subjects, without entering into details, and referring for these to the elaliorate discussions of Schimpcr, Williamson, and McXab, and to my paper on the subject, " Journal of the Geological Society," vol. xxvii, p. 54, I may remark : IMAGE EVALUATION TEST TARGET (MT-3) 1.0 I.I IIIM IIM IIM i^ m III 2.0 1.8 1.25 1.4 1.6 M 6" — ► V} <9 //, mp ^^> #- p^* '3 ^ > r^^> 23 WEST MAIN STREET WEBSTER, NY. 14S80 (716) 872-4503 f^ w- 170 THE GEOLOGICAL HISTORY OF PLANTS. :!| i-i S I i^u - ! ; 1. That the aerial stems of ordinary Calamites had a thin cortical layer, with lacunae and fibrous bundles and multiporous vessels — the whole not differing much from the structure of modern Equiscta. 2. Certain arborescent forms, perhaps allied to the true Calamites, as well as possibly the old underground stems of ordinary species,* assumed a thick-walled character in which the tissues resembled the wedges of an exogen, and abundance of pseudo-scalariform fibres were developed, while the ribbitig of the external surface became obsolete or was replaced by a mere irregular wrinkling. - '._-'■ 3. Sufficient discrimination has not been exercised in separating casts of the internal cavities of Calamites and Calamodendron from those representing other surfaces and the proper external surface. 4. There is no excuse for attributing to Calamites the foliage of Annularia, Asterophyllites, and Sphenophyllum, since these leaves have not been found attached to true Calamite stems, and since the structure of the stems of Asterophyllites as described by Williamson, and that of Sphenophyllum as described by the writer,f are essen- tially different from those of Calamites. 5. As the species above described indicates, good external char- acters can be found for establishing species of this genus, and these species are of value as marks of geological age. ' ' Genus Arch.^ocalamites, Sternberg. Tills genus has been established to include certain Calamites of the Devonian ai.'l Lower Carboniferous, in which the furrows on the stem do not alteri ate at the nodes or joints, and the leaves in one species at least bifurcate. C. radiatus, Brongniart, is the typical species. In North America it occurs in the Erian, probably as low as the Middle Erian. In Europe it has so far been recognised in the Lower Carboniferous only. I have, however, seen stems from alleged Devonian beds in Devonshire which may have belonged to this species. Family AsTEROPiiYLLiTEiE; Oenus Asterophyllites, Brongniart. Stems ribbed and jointed like the Calamites, but with inflated nodes and a stout internal woody cylinder, which has been described by Williamson. From the joints proceeded whorls of leaves or of branchlets, bearing leaves which differed from those of Calamites in their having a distinct middle rib or vein. The fructification con- * Williamson, " Transactions of the Royal Society." "Proceedings of the Edinburgh Botanical Society." f "Journal of the Geological Society," 1866. McNab, in THE CARBONIFEROUS FLORA. 171 sisted of long slender cones or spikes, having whorls of scales bear- ing the sporo-cases. Some authors speak of AsterophyUitea as only branches ai 1 leaves of Calamites; but though at first sight the re- semblance is great, a close inspection shows that the leaves of As- terophyllites have a true midrib, which is wanting in Calamites. Genus Annularia. — It is perhaps questionable whether these plants should be separated from AsterophyUifes. The distinction is that they produce branches in pairs, and that their whorls of leaves are one-sided and usually broader than those of AsterophyUifes, and united into a ring at their insertion on the stem. One little speciea, A. sphenophylloides, is very widely distributed. PiNNULARiA — a provisional genus — includes slender roots or stems branching in a pinnate manner, and somewhat irregularly. They are very abundant in the coal shales, and were probably not inde- pendent plants, but aquatic roots belonging to some of the plants last mentioned. The probability of this is farther increased by their resemblance in miniature to the roots of Calamites, They are always flattened, but seem originally to have been round, with a slender thread-like axis of scalariform vessels, enclosed in a soft, smooth, cellular bark. Family Rihzocarpe^^ ; Genus Sphenopiiyllum. . i Leaves in whorls, wedge-shaped, with forking veins. Fructi- fication on spikes, with verticils of sporocarps. These plants are by some regarded as allied to the Calamifem and Asterophyllitece, by others as a high grade of Rhizocarps of the type of Marsilia. The stem had a star-shaped central bundle of scalariform or reticulato- scalariform vessels. : Genus SpoRAyaiTES. (Sporocarpon, VliUiamson.) Under this name we may provisionally include those rounded spherical bodies found in the coal and its accompanying beds, and also in the Eriiin, which may be regarded as IMacrospores or Sporo- carps of Protosr-Vinia, or other Khizocarpean plantsakin to those de- scribed above in Chapter III, which see for description. Genus Protosalvinia. — Under this we include sporocarps allied to those of Salvinia, as described in Chapter III. Family FiucES. Under this head I shall merely refer to a few groups of special interest, and to the provisional arrangement adopted for the fronds of ferns when destitute of fructification. 172 THE GEOLOGICAL HISTORY OF PLANTS. Ivl U The external appearances of trunks of tree-ferns have been al- ready referred to. With respect to tree ferns, the oldest known examf)]es are those from the Middle Devonian of New York and Ohio, which I have de- scribed in the "Journal of the Geological Society," 1871 and 1881. As these are of some interest, I have reproduced their descriptions in a note appended to Chapter III, which see. The other forms most frequently occurring in the Carboniferous are Caulopteris, Palceopferis, and Megaphyton.* Stems showing merely masses of aerial roots are known by the name Psaronius. With reference to the classification of Palaeozoic ferns, this has hitherto been quite arbitrary, being based on mere form and vena- tion of fronds, but much advance has recently been made in the knowledge of their fructification, warranting a more definite at- tempt at classification. The following are provisional genera usu- ally adopted : 1. Cydopteris, Brongniart. — Leaflets more or less rounded or wedge-shaped, without midrib, the nerves spreading from the point of attachment. This group includes a great variety of fronds evi- dently of diilerent genera, were their fructification known ; and some of them probably portions of fronds, the other parts of which may be in the next genus. 2. Neuropteris, Brongniart. — Fronds pinnate, and with the leaflets narrowed at the base ; midrib often not distinct, and disap- pearing toward the apex. Nervures equal, and rising at an acute angle. Ferns of this type are among the most abundant in the coal- formation. 3. Odontopteris, Brong. 'art. — In these :he frond is pinnate, and the leaflets are attached by their whole base, with the nerves either proceeding wholly from the base, or in part from an indistinct mid- rib, which soon divides into nervures. 4. Dictyopteris, Gutbier. — This is a beautiful style of fern, with leaflets resembling those of Neuropteris, but the veins arranged in a network of oval spaces. Only a few species are known in the coal- formation. 5. Lonchopteris, Brongniart. — Ferns with netted veins like the above, but with a distinct midrib, and the leaflets attached by the whole base. Of this, also, we can boast but few species. 6. Sphenopteris, Brongniart. — These are elegant ferns, very nu- merous in species, and most difficult to discriminate. Their mos'i * See my " Acadian Geology," also below. THE CARBONIFEROUS FLORA. 173 distinctive characters are leaflets narrowed at the base, often lobed, and with nervures dividing in a pinnate manner from the base. 7. Fhyllopteris, Brongniart. — These are pinnate, with long lan- ceolate pinnules, having a strong and well-defined midrib, and nerves proceeding from it very obliquely, and dividing as they pro- ceed toward the margin. The ferns of this genus are for the most part found in formations more recent than the Carboniferous ; but I have referred to it, with some doubt, one of our species. 8. Alethopteris, Brongniart. — This genus includes many of the most common coal-formation ferns, especially the ubiquitous A. lon- chifica, which seems to have been the common brake of the coal- formation, corresponding to Pteris aquilina in modern Europe and America. These are brake-like ferns, pinnate, with leaflets often long and narrow, decurrent on the petiole, adherent by their whole base, and united at base to each other. The midrib is continuous to the point, and the nervures run off from it nearly at right angles. In some of these ferns the fructification is known to have been mar- ginal, as in Pteris. 9. Pecopteris, Brongniart. — This genus is intermediate between the last and Neuropteris. The leaflets are attached by the whole base, but not usually attached to each other; the midrib, though slender, attains to the summit; the nervures are given off less ob- liquely than in JSeuropteris. This genus includes a large number of our most common fossil ferns. 10. Beinertia, Goeppert. — A genus established by Goeppert for a curious Pecopteiis-liko fern, with flexuous branching oblique ner- vures becoming parallel to the edge of the frond. 11. Hymenophyllites, Goeppert. — These are ferns similar to Sphenopteris, but divided at the margin into one-nerved lobes, in the manner of the modern genus HymenophyUum, 12. Palffopferis, Geinitz. — This is a genus formed to mclude cer- tain trunks of tree-ferns with oval transverse scars of leaves. 13. Cnulopferis, Lindley and Hutton. — Is another genus of fossil trunks of tree-ferns, but with elongate scars of loaves. 14. Psaronins, Cotta. — Includes other trunks of tree-ferns with alternate scars or thick scales, and ordinarily with many aerial roots grouped round them, as in some modern tree-ferns. 15. Megaphyton, Artis. — Includes trunks of tree-ferns which bore their fronds, which were of great size, in two rows, one on each side of the stem. These were very peculiar trees, less like modern ferns than any of the others. My reasons for regarding thera as ferns are stated in the following extract from a recent paper : 174 THE GEOLOGICAL HISTORY OF PLANTS. Ii1!'-^ "Their thick stems, marked nith linear scars and having two rows of large depressed areoles on the sides, suggest no affinities to any known plants. They are usually ranked with Lepidodendron and Ulodendron, but sometimes, and probably with greater reason, are regarded as allied to tree-ferns. At the Joggins a very fine species (Jf. magnificum) has been found, and at Sydney a smaller species (M. humile) ; but both are rare and not well preserved. If the large scars bore cones and the smaller bore leaves, then, as Bron- gniart remarks, the plant would much resemble Lepidophloios, in which the cone-scars are thus sometimes distichous. But the scars are not round and marked with radiating scales as in Lepidophloios; they are reniform or oval, and resemble those of tree-ferns, for which reason they may bo regarded as more probably leaf-scars ; and in that case the smaller linear scars would indicate ramenta, or small aerial roots. Further, the plant described by Corda as Zippea die- ticha is evidently a Megaphyton, and the structure of that species is plainly that of a tree-fern of somewhat peculiar type. On these grounds I incline to the opinion of Geinitz that these curious trees were allied to ferns, and bore two rows of large fronds, the trunks being covered with coarse hairs or small aerial roots. At one time I was disposed to suspect that they may have crept along the ground ; but a specimen from Sydney shows the leaf-stalks proceeding from the stem at an angle so acute that the stem must, I think, have been erect. From the appearance of the scars it is probable that only a pair of fronds were borne at one time at the top of the stem ; and, if these were broad and spreading, it would be a very graceful plant. To what extent plants of this type contributed to the accumulation of coal I have no means of ascertaining, their tissues in the state of coal not being distinguishable from those of ferns and Lyco- podiacecey • 16. For descriptions of the genus Archmopteris and other Erian ferns, see Chapter III. ,. :i. i wa j-j CHAPTER V. ,i^i THE FLORA OF THE EARLY MESOZOIC. Great physical changes occurred at the close of the Carboniferous age. The thick beds of sediment that had been accumulating in long lines along the primitive con- tinents had weighed down the earth's crust. Slow sub- sidence had been proceeding from this cause in the coal- formation period, and at its close vast wrinklings occurred, only surpassed by those of the old Laurentian time. Hence in the Appalachian region of America we have the Carboniferous heds tiirown into abrupt folds, their shales converted into hard slates, their sandstones into quartzite and their coals into anthracite, and all this before the deposition of the Triassic Red Sandstones which consti- tute the earliest deposit of the great succeeding Mesozoic period. In like manner the coal - fields of Wales and elsewhere in western Europe have suffered similar treat- ment, and apparently at the same time. This folding is, however, on both sides of the Atlantic limited to a band on the margin of the continents, and to certain interior lines of pressure, while in the middle, as in Ohio and Illinois in America, and in the great interior plains of Europe, the coal-beds are undisturbed and un- altered. In connection with this we have an entire change in the physical character of the deposits, a great elevation of the borders of the continents, and probably a considerable deepening of the seas, leading to the estab- lishment of general geographical conditions which still remain, though they have been temporarily modified by subsequent subsidences and re-elevations. nif M 1 ■ ^i! i '>i lilt ! ; i 170 THE GEOLOGICAL HISTORY OF PLxVNTS. Along with this a great cliange was in progress in vegetable and animal life. The flora and fauna of the Paleozoic gradually die out in the Permian and are re- placed in the succeeding Trias by those of the Mesozoic time. Throughout the Permian, however, the remains of the coal-formation flora continue to exist, and some forms, as the Calamites, even seem to gain in importance, as do also certain types of coniferous trees. The Triassic, as well as the Permian, was marked by i)hysical disturb- ances, more especially by great volcanic eruptions dis- charging vast beds and dykes of lava and layers of volcanic ash and agglomerate. This was the case more especially along the margins of the Atlantic, and probably also on those of the Pacific. The volcanic sheets and dykes as- sociated with the Red Sandstones of Nova Scotia, Con- necticut, and New Jersey are evidences of this. At the close of the Permian and beginning of the Trias, in the midst of this transition time of physical disturbance, appear the great reptilian forms character- istic of the age of reptiles, and the earliest precursors of the mammals, and at this time the old Carboniferous forms of plants finally pass away, to be replaced by a flora scarcely more advanced, though different, and con- sisting of pines, cycads, and ferns, with gigantic equiseta, which are the successors of the genus Calamites, a genus which still survives in the early Trias. Of these groups the conifers, the ferns, and the equiseta are already famil- iar to us, and, in so far as they are concerned, a botanist who had studied the flora of the Carboniferous would have found himself at home in the succeeding period. The cycads are a new introduction. The whole, how- ever, come within the limits of the cryptogams and the gymnosperms, so that here we have no advance.* * Fontaine's " Early Mesozoic Flora of Virginia " gives a very good summary of this flora in America, , . 1 TliE FLORA. OF THE EARLY MESOZOIC. 177 As we ascend, Jiowever, in the Mesozoic, we find new and higher types. Even within the Jurassic epoch, the next in succession to the Trias, there are clear indica- tions of tlie presence of the cndogens, in species allied to Fia. 6-i. — Jurassic vegetation. Cycads and pines. (After Saporta.) the screw-pines and grasses ; and the palms appear a little later, while a few exogenous trees have left their remains in the Lower Cretaceous, and in the Middle and Upper Cretaceous these higher plants come in abund- antly and in generic forms still extant, so that the dawn of the modern flora belongs to the Middle and Upper 17 178 THE GEOLOGICAL HISTORY OF PLANTS. Cretaceous. It will thus be convenient to confine our- selves in this chapter to the flora of the earlier Mesozoic. Passing over for the present the cryptogamous plants already familiar in older deposits, we may notice the new features of gymnospermous and phaenogamous life, as they present themselves in this earlier part of the great rep- tilian age, and as they extended themselves with remark- able uniformity in this period over all parts of the world. For it is a remarkable fact that, if we place together in our collections fossil plants of this period from Australia, India, China, Siberia, Europe, or even from Greenland, we find wonderfully little difference in their aspect. This uniformity we have already seen prevailed in the Palaeo- zoic flora ; and it is perhaps equally marked in that of the Mesozoic. Still we must bear in mind that some of the plants of these joeriods, as the ferns and pines, for example, are still world - wide in their distribution ; but this does not apply to oth- ers, more especially the cycads (Fig. 65). The cycads consti- tute a singular and ex- ^^^^^ , ceptional type in the "^ ~"^ ^"^--v^ 11 i/ modern world, and are limited at present to the warmer cli- mates, though very generally distributed in these, as they oc- cur in Africa, India, Japan, Australia, Mexico, Florida, and the West Indies. In the Mesozoic age, however, they were world-wide in their distribution, and are found as far north as Green- land, though most of the species found in the Cretaceous Fig. 65, — Podozamites lanceolatus, Stcrab. L. Cretaceous. THE FLOliA OP THE EARLY MESOZOIC. 179 of that country are of small size, and may have been of low growth, 80 that tliey may have been protected by the snows of winter. The cycads have usually simple or un- branching stems, pinnate leaves borne in a crown at top, and fruits which, though somewhat various in structure and arrangement, are all of the sim})ler form of gymno ■ spermous type. The stems are exogenous in structure, but with slender wood and thick bark, and barred tissue, or properly as tissue intermediate between this and the disc-bearing fibres of the pines. Though the cycads have a considerable range of or- ganisation and of fructification, and though some points in reference to the latter might assign them a higher place, on the whole they seem to occupy a lower position than the conifers or the cordaitcfe of the Carboniferous. In the Carboniferous some of the fern-like leaves assigned to the genus Noefjgerathia have been shown by Stur and Weiss to have been gymnosperms, probably allied to cycads, of which they may be regarded at least as pre- cursors. Thus the cycadean type does not really consti- tute an advance in grade of organisation in the Mesozoic, any further than that, in the period now in question, it becomes much more developed in number and variety of forms. But the conifers would seem to have had preced- ence of it for a long time in the Palajozoic, and it replaces in the Mesozoic the Cordaites, which in many respects excelled it in complexitj^ The greater part of the cycads of the Mesozoic age would seem to have had short stems and to have consti- tuted the undergrowth of woods in which conifers at- tained to greater height. An interesting case of this is the celebrated dirt-bed of the quarries of the Isle of Port- land, long ago described by Dean Buckland. In this fossil soil trunks of pines, which must have attained to great height, are interspersed with the short, thick stems of cycads, of the genus named Cycadoidea by Buckland, r!_Li. M. i\ hi '■V » ' 'ir " si! M 180 THE GEOLOGICAL HISTORY OF PLANTS. and which from their appearance ai-e called "fossil birds' nests '' by the quarry men. Some, however, must have attained a considerable height so as to resemble palms. The cycads, with their simple, thick trunks, usually marked with rhombic scars, and bearing broad spreading crowns of large, elegantly formed pinnate loaves, must have formed a prominent part of the vegetation of the northern hemis])here during the whole of the Mesozoic period. A botanist, had there been such a person at the time, would have found this to be the case everywhere from the equator to Spitzbcrgen, and probably in the southern hemisphere as well, and this throughout all the long periods from the Early Trias to the Mit 'le Cre- taceous. In a ^.aper published in the ** Linua?ai Trans- actions" for 1808, Dr. Carruthers enumerates twenty spe- cies of British Mesozoic cycads, and the number might now be considerably increased. The pines present some features of interest. We have already seen ti;eir connection with the broad-leaved Cor- daites, and in the Permian there are some additional types of broad -leaved coniferce. In the Mesozoic we have great numbers of beautiful trees, with those elegant fan-shaped leaves characteristic of but one living species, the Salisburia, or gingko-tree of China. It is curious that this tree, though now limited to eastern Asia, will grow, though it rarely fruits, in most parts of tem- perate Europe, and in America as far north as Montreal, and that in the Mesozoic period it occupied all these re- gions, and even Siberia and Greenland, and with many and diversified species (Fig. 6G). Fio. 66. — Salisburia (Gingko) ISihirica. Ileer. L. C'lvta- ceouti, Siboria and North America. THE FLORA OF THE EARLY MEriOZOIC. 181 Salisburia belongs to the yews, but an equally curious fact applies to the cypresses. The genus Sequoia, limited at present to two species, both Californian, and one of them the so-called **big tree," celebrated for the gigantic size to which it attains, is represented by species found as far back at least as the Lower Cretaceous, and in every part of the northern hemi- sphere.* It seems to have thriven in all these regions throughout tiie Mesozoic and early Kainozoic, and then to have disappeared, leaving only a small rem- nant to represent it in modern days. A number of species have been de- scribed from the Mesozoic and Tertiary, all of them closely related to those now existing (Fig. G7). The following notice of these trees is for the most part translated, with some modifications and abridg- ment, from a paper read by the late Prof. Heer be- fore the Botanical Section of the Swiss Natural His- tory Society : The name itself deserves consideration. It is that of an Indian of the Cherokee tribe, Sequo Yah, who in- ven' .m alphabet without ar.y aid from the outside world of culture, and taught it to his tribe by writing it upon Fic. 07.- -Sequoia Smithiana, Heer. L. Cretaceous. * In the Eocene of Australia. 182 THE UKOLOGICAL IIISTOUY OF PLANTS. loaves. 'IMiis ciune into goneriil use among tlio Chcro- kcos, before the white man had any knowlo(lUH, but we have received accurate accounts of them from Prof. Whitney. Tho tallest tree measured by him has a hei^dit of '^25 feet, and in tho case of one of the trees the number of tho ring's of <,'rowth indicated an age of about 1,300 years. Jt had a <,'irth of 60 to 00 feet. We know only two livini,' spreies of Sequoia, both of which arc^ conlined to California. The oiu' (*S'. seniprr' virvns) is (-lolhed with erect leaves, arranS^. Nordenskioldi, Hr.). These have been met with in Greenland and Spitzbergen, and one of them has lately been found in the United States. Three other species, in addition to these, have been described by Lesquereux, which appear to belong to the group of the S. Langsdorfii, viz., S. longifoUa, Lesq., S. angtistifolia, and S. acu- minata, Lesq. Several species also occur in the Creta- ceous and Eocene of Canada. These species thus answer to the living Sequoia scm- pervirens ; but we can also point to Tertiary represen- * It is Fareilca Campbelli of Forbes. THE FLORA OF THE EARLY MESOZOIC. 185 tativos of the S. ;'igantea. Their leaves are stiff and sharp-pointed, are thinly set round the branches, and lie forward in the same way : the egg-shaped cones are ia some cases similar. There are, however, in the early Tertiary six species, which fill up the gap between 6'. sempervirens and S. gigantea. They are the S. Couttsim, S. affinis, Lesq., S. imbricata, Hr., S. sibirica, Hr., 8. Heerii, Lesq., and S. biformis, Lesq. Of these, 8. Couttsim, Hr., is the most common and most important species. It has short leaves, lying olong the branch, like 8. gigantea, and small, round cones, like 8. Langsdorjii and sempervirens. Bovey Tracey in Devonshire has afforded splendid speci- mens of cones, seeds, and twigs, which have been described in the " Philosophical Transactions." More lately. Count Saporta has described specimens of cones and twigs from Armissan. Specimens of this species have also been found in the older Tertiary of Greenland, so that it must have had a wide range. It is very like to the American 8. affinis, Lesq. In the Tertiary there have been already found fourteen well-marked species, which thus include representatives of the two living types, 8. sempervirens and 8. gigantea. We can follow this genus still further back. If we go back to the Cretaceous age, we find ten species, of which five occur in the Urgon of the Lower Cretaceous, two in the Middle, and three in the Upper Cretaceous. Among these, the Lower Cretaceous exhibits the two types of the 8equoia sempervirens and 8. gigantea. To the former the 8. 8mithia?ia answers, and to the latter, the Reichen- bacJiii, Gein. The ^S'. 8mit1iiana stands indeed uncom- monly near the 8. Langsdorjii, both in the appearance of the leaves on the twigs and in the shape of the cones. These are, however, smaller, and the leaves do not become narrower toward the base. The 8. pectina, Hr., of the Upper Cretaceous, has its leaves arranged in two rows, and PI" 186 THE GEOLOGICAL HISTORY OF PLANTS." t ! I |ii' m< I » presents a similar appearance. The S. Eeichenbachii is a type more distinct from those nc \y living and those in the Tertiary. It has indeed stiff, pointed leaves, lying forward, but they are arcuate, and the cones are smaller. Tills tree has been known for a long time, and it serves in the Cretaceous as a guiding star, which we can follow from the TJrgoniaa of the Lower Cretaceous up to the Cenomanian. It is known in France, Belgium, Bohemia, Saxony, Greenland, and Spitzbergen (also in Canada and the United States). It has been placed in another genus — Geinitzia — but we can recognise, by the help of the cones, that it belongs to Sequoia. Below this, there is found in Greenland a nearly re- lated species, the S. amhigua, Ilr., of which the leaves are shorter and broader, and the cones round and some- what smaller. The connecting link between 8. Smitliiana and Reich- enlachii is formed by S. suhidata, Ilr., and S. rifjida^ Hr., and three species (*S'. gracilis, Ilr., 8. fastigiata and 8. Gardneriana, Cair.), with leaves lying closely along the branch, and which come very near to the Tertiary species 8. Couttsim. We have therefore in the Cretaceous quite an array of species, which fill up the gap between the 8. sempervirens and gigantea, and show us that the genus Sequoia had already attained a great development in the Cretaceous. This was still greater in the Tertiary, in which it also reached its maximum of geographical dis- tribution. Into the present world the two extremes of the genus have alone continued ; the numerous species forming its main body have fallen out in the Tertiary. If we look still further back, we find in the Jura a great number of conifers, and, among them, we meet in the genus Pinus with a typo which is highly developed, and which still survives ; but for Sequoia we have till now looked in vain, so that for the present we can not place the rise of the genus lower than the Urgonian of the Cre- THE FLORA OF THE EARLY MESOZOIC. 187 1! taceous, however remarkable we may think it that in that period it should have developed into so many species ; a;id it is still more surprising that two species already make their appearance which approach so near to the living Sequoia sempervirens and S, gigantea. Altogether, we have become acquainted, up to Hie present time, with twenty-six species of Sequoia. Four- teen of these species are found in the Arctic zone, and have been described and figured in the ** Fossil Flora of the Arctic Eegions." Sequoia has been recognised by Ettingshausen even in Australia, but there in the Eocene. This is, perhaps, the most remarkub^: record in the whole history of vegetation. The Sequoias are the giants of the conifers, the grandest representatives of the family, and the fact that, after spreading over the whole northern hemisphere "nd attaining to more than twenty specific forms, their decaying remnant should now be confined to one limited region in western America and to two species constitutes a sad memento of departed greatness.* The small remnant of S. gigantea still, however, towers above all competitors, as eminently the " big trees " ; but, had they and the allied species failed to escape the Tertiary continental submergences rnd the disasters of the glacial period, this grand genus would have been to us an extinct type. In like manner the survival of the single gingko of eastern Asia alone enables us to understand that great series of taxine trees with fern-like leaves of which it is the sole representative. Besides these peculiar and now rare forms, we hu, : in the Mesozoic many others related closely to existing yews, cypresses, pines, and spruces, so that the conifers were probably in greater abundance and variety than they are at this day. * The writer has shown that much of the material of the great lignite bods of the Canadian Northwest consists of wood of Sequoia of both the modem types. 188 THE GEOLOGICAL HISTORY OF PLANTS. :l- ir Vi K In this period, also, we find the earliest representatives of the endogenous plants. It is true that some plants found in the coal-formation have '^een doubtfully re- ferred to these, but the earliest certain ex imples would seem to be some bamboo-like and screw-pine-like plants occurring in the Jurassic rocks. Some of these are, it is true, doubtful forms, but of others there seems to be no question. The modern Pandanus or screw-pine of the tropical regions, which is not a pine, however, but a humble relation of the palms, is a stiffly branching tree, of a candelabra-like form, and with tufts of long leaves on its branches, and nuts or great hard berries for fruit, borne sometimes in large masses, and so protected as to admit of their drifting uninjured on the sea. The stems are supported by masses of aerial roots like those which strengthen the stems of tree-ferns. These structures and habits of growth fit the Pandanus for its especial habitat on the shores of tropical islands, to which its masses of nuts are drifted by tb winds and currents, and on whose shores it can establish itself by the aid of its aerial roots. Some plants referred to the cycads have proved veri- table botanical puzzles. One of these, the Williamsonia gigas of the English oolite, originally discovered by my friend Dr. Williamson, and named by him Zamia gigas, a very tall and beautif il species, found in rocks of this age in various parts of Europe, has been claimed by Saporta for the EnJogens, as a plant allied to Pandanus. Some other botanists have supposed the flowers and fruits to be parasites on other plants, like the modern Raffiesia of Sumatra, but it is possible that after all it may prove to have been an aberrant cycad. The tiee-palms are not found earlier than the Middle Cretaceous, where we shall notice them in the next chap- ter. In like manner, though a few Angiosperms occur in rocks believed to be Lower or Lower Middle Cretaceous in Greenland and the northwest territory of Canada, and r*'M*^»^'«v»r THE FLORA OF THE EARLY MESOZOIC. 189 '1 in Virginia, these are merely precursors of those of the Upper Cretaceous, and are not satHcient to redeem the earlier Cretaceous from being a period of pines and cycads. On the whole, this early Mesozoic flora, so far as known to us, has a monotonous and mean appearance. It no doubt formed vast forests of tall pines, perhaps re- sembling the giant Sequoias of California ; but they must for the most part have been dark and dismal woods, probably tenanted by few forms of life, for the great rep- tiles of this age must have preferred the open and sunny coasts, and many of them dwelt in the waters. Still wo must not be too sure of this. Tiie berries and nuts of the numerous yews and cycads were capable of affording much food. We know that in this age there were many great herbivorous reptiles, like Ifjiianodon and Hadrosau- rus, some of them fitted by their structure to feed upon the leaves and fruits of trees. There were also several kinds of small herbivorous mammals, and much insect life, and it is likely that few of the inhabitants of the Mesozoic woods have been preserved as fossils. We may yet have much to learn of the inhabitants of these forests of ferns, cycads, and i)incs. We must not forget in this connection that in the present day there are large islands, like New Zealand, destitute of mammalia, and having a flora comparable with that of the Mesozoic in the northern hemisphere, though more varied. We have also the re- markable example of Australia, with a much richer flora than that of the early Mesozoic, yet inhabited only by non-placental mammals, like those of the Mesozoic. The principal legacy that the Mesozoic woods have handed down to our time is in some beds of coal, locally important, but of far less extent than those of the Car- boniferous period. Still, in America, the Richmond coal- field in Virginia is of this age, and so are the anthracite beds of the Queen Charlotte Islands, on the west coast of Canada, and the coal of Brora in Sutherlandshire. Valu- 18 m m ;'■!!' r^ F f 5t i It III i ! xc i 1 ifir 1 -i ' it i t 1 i\ • 'it I 1 9 ■ ' 1 i ; ( 1 t ^ ii iJ t 190 THE GEOLOGICAL HISTORY OF PLANTS. able beds of coal, probably of this age, also exist in China, India, and South Africa ; and jet, which is so extensively used for ornament, is principally derived from the car- bonised remains of the old Mesozoic pines. In the next chapter we have to study a revolution in vegetable life most striking and unique, in the advent of the forest-trees of strictly modern types. , ^ , ; . NOTE TO CHAPTER V. I APPEND to this chapter a table showing the plant-bearing series of the Cretaceous and Laramie of North America, from a paper in " Trans. R. S. C," 1885, which see for further details : • ; . , , (In Descending Order.) Period!. Flora* and tabflorag. Raferencni, Transition Eocene to Cretaceous. Upper Laramie or Porcu- pine Hill. Fort Union group, U S. territory. Platanus beds of Souris River and Calgary. Rep of 1885. CHAPTER VI. THE REIGN OF ANGI3SPERMS IN THE LATER CRETACEOUS AND KAINOZOIC. It is a remarlcable fact in geological chronology that the culmination of the vegetable kingdom antedates that of the animal. The placental mammals, the highest group of the animal kingdom, are not known till the be- ginning of the Eocene Tertiary. The dicotyledonous Angiosperms, which correspond to them in the vegetable king- dom, occur far earlier — in the beginning of the Upper Cre- taceous or close of the Lower Cretaceous. The reign of cy- cads and pines holds through- out the Lower Cretaceous, but at the close of that age there is a sudden incoming of the high- er plants, and a proportionate decrease, more especially of the cycads. I have already referred to the angiospermous wood supposed to be Devonian, but I fear to rest any conclusion on this iso- lated fact. Beyond this, the earliest indications of plants of this class have been found in the Lower Cretaceous. Many years ago Heer described and fig- ured the leaves of a poplar {Fopulus primceva) from Fio. 68. — IbpvlusprimcEva^ liter. Cretaceous, of Greenland. One of the oldest known Angio- eporuis. Illi tin 'II' i ' I t w \ i 1 , ! J I r 11 -T '-^ ^if E ! ' li^ i!i ! ;'Hi: 102 THE GEOLOGICAL HISTORY OF PLANTS. the supposed Lower Cretaceous of Kome, in Greenland (Fig. G8). Two species, af Sterculia and a Laurus or Salix, occur among fossils described by me in the upper part of the Kootanie series of the llocky Mountains, and Fontaine has recently found in the Potomac group of Virginia — believed to be of Neoconiian age — several angio- spermous sj)ecies {Sassafras, Mcnispermitesy Sapindus, Aralia, Pojmlusy &c. ) mixed with a rich flora of cycads and pines. These are the early forerunners of the mod- ern angiospermous flora ; but so far as known they do not occur below the Cretaceous, and in its lower portions only very rarely. When, however, we ascend into the Upper Cretaceous, whether of Euro})e or America, there is a remarkable incoming of the higher plants, under generic forms similar to those now existing. This is, in truth, the advent of the modern flora of the temperate regions of the earth. A very interesting tabular view of its early distribution is given by Ward, in the "American Journal of Science " for 1884, of which the following is a synopsis, with slight emendations. I may add that the new discoveries made since 1884 would probably tend to increase the proportionate number of dicotyledons in the newer groups. Dicotyledonous Trees in the Cretaceoc8. Upper Senonian 179 species. (Fox Hill group of America.) Lower Senonian 81 species. Upper white chalk of Europe; Fort Pierre group of America ; coal-measures of Na- naimo ? Turanian 20 species. Lower white chalk ; New Jersey marls ; Belly R. group. Cenomaiiian 357 species. (Chalk-marl, grcensand, and Gault, Niobrara and Dakota groups of America) ; Dun- vegan group of Canada; Amboy clays of A- New Jersey. J:!^!i LATER CRETACEOUS AND KAINOZOIC. 193 Neoenmian (Lower grcensand and Specton clay, Wealden and Hastings sands, Kootanie and (jucca Charlotte groups of Canada.) 20 species; Thus we have a great and sudden inswarming of the higher plants of modern types at the close of the Lower Cretaceous. In relation to this, Saporta, one of the most enthusiastic of evolutionists, is struck by this phenome- non of the sudden appearance of so many forms, and some of them the most highly differentiated of dicotyle- donous plants. The early stages of their evolution may, he thinks, have been obscure and as yet unobserved, or they may have taken place in some separate region, or mother country as yet undiscovered, or they may have been produced by a rapid and unusual multiplication of flower-haunting insects ! Or it is even conceivable that the apparently sudden elevation of plants may have been due to causes still unknown. This last seems, indeed, the only certain inference in the case, since, as Saporta proceeds to say in conclusion : ** Whatever hypothesis one may prefer, the fact of the rapid multiplication of dicotyledons, and of their simultaneous appearance in a great number of places in the northern hemisphere at the beginning of the Cenomanian epoch, cannot be dis- puted."! The leaves described by Heer, from the Middle Cre- taceous of Greenland, are those of a poplar {P. primcBva). Those which I have described from a corresponding hori- zon in the Rocky Mountains are a Sterculites {S. vetus- tula), probably allied to the mallows, and an elongated leaf, Laurophyllum (L. crassinerve) (Fig. 69), which may, however, have belonged to a willow rather than a laurel. These are certainly older than the Dakota group ''li * Including an estimate of Fontaine's undescribed species, f "Monde des Plantca," p. 197. I i ' I i I «i m 194 THE GEOLOGICAL HISTORY OF PLANTS. of tlic United States and the corre.sponding formations in Canada. On the eastern side of the American conti- nent, in Virginia, the Potomac series is siipi)oscd to be of Lower Cretaceous age, and here Fontaine, as already stated, has found an abundant llora of cy- cads, conifers, and ferns, with a few angiosperm- ous leaves, which have not yet been described. In the Canadian Rocky Mountains, ix few hun- dreds of feet above the beds holding the before- mentioned species, are the shales of the Mill Creek scries, rich in many spe- cies of dicotyledonous leaves, and corresponding in age with the Dakota group, whose fossils have been so well described, first by Heer and Capellini, and afterward by Lesquereux. We may take this Dakota group and the quader-sandstone of Ger- many as types of the plant-bearing Cenomanian, and may notice the forms occurring in them. In the first place, we recognise here the successors of our old friends, the ferns and the iiines, the latter repre- sented by such genera as Taxites, btquoiay Ghjptostrobus, Gingko, and even Pimts itself. We also have a few cycads, but not so dominant as in the previous ages. The fan-palms are well represented, both in America and in the corresponding series in Europe, especially by the genus Sabal, which is the characteristic American type of fan-palm, and there is one genus which Saporta regards as intermediate between the fan-palms and the pinnately leaved species. There are also many fragments of stems Fio. 69. — Rtercalia and Ljllum or Sdli.e, the oklcf*t Aiij?iosi>ernis known in tho Cretaceous of Canada. ■^•T'^-W^r*?*!*/* LATER CRETACEOUS AND KAINOZOIC. 195 ami leaves of carices and grasses, so that these i)lants, now so importiint to the nourishment of man and his com- panion animals, were already rei)resented. Fio. 70. — Vegetation of Later Cretnceoua. Exogens and palms. (Atlor Saporta.) But the great feature of the time was its dicotyle- donous forests, and I have only to enumerate the genera supposed to be represented in order to show the richness of the time in plants of this type. It may be necessary to explain here that th generic names used are mostly based on leaves, and consequently cannot be held as being 196 THE GEOLOGICAL HISTORY OF PLANTS. absolutely certain, since we know that at present one genus may have considerable variety in its leaves, and, on the other hand, that plants of different genera may be very much alike in their foliage. There is, however, un- doubtedly a likeness in plan or type of structure in leaves of closely allied plants, and, therefore, if judiciously studied, they can be determined with at least approxi- mate certainty.* More especially we can attain to much certainty when the fruits as well as the leaves are found, and when we can obtain specimens of the wood, showing its structure. Such corroboration is not wanting, though unfortunately the leaves of trees are generally found drifted away from the other organs once connected with them. In my own experience, however, I have often found determinations of the leaves of trees confirmed by the discovery of their fruit? or of the structure of their stems. Thus, in the rich cretaceous plant-beds of the Dunvegan series we have bt;ech-nuts associated in the same beds with loaves referred to Fagus. In the Laramie beds I determined many years ago nuts of the Trapa or water-chestnut, and subsequently Lesquereux found, in beds in the United States, leaves which he referred to the same genus. Later, I found in collections made on the Red Deer River of Canada my fruits and Lesquereux's leaves on the same slab. The presence of trees of the genera Carya and Juglans in the same formation was in- ferred from their leaves, and specimens have since been obtained of silicified wood, with the microscopic structure of the modern butternut, ^till we are willing to admit that determinations from leaves alone are liable to doubt. In the matter of names of fossil leaves, I sympathise very strongly with Dr. Nathorst, of Stockholm, in his * Great allowance has to be made for the variability of leaves of the same species. The modern hazel (C. rostrata) is a case in point. Its leaves, from different parts of the same plant, are so dissimilar in form and size that tbey might readily be regarded as of different species. LATER CRETACEOUS AND K VINOZOIC. 197 objection to the use of modern generic names for mere leaves, and would be quite content to adopt some non- committal termination, as that of '^phyllum" or '^iies" suggested by him. I feel, however, tliat almost as much is taken for granted if a plant is called Corylophyllum or Corylites, as if called Corylus. In either case a judgment is expressed as to its affinities, which if wrong under the one term is wrong under the other; and after so much haa been done by so many eminent botanists, it seems inex- pedient to change the whole nomenclature for so small and questionable an advantage. I wish it, however, to be distinctly understood that plants catalogued on the evidence of leaves alone are for the most part referred to certain genera on grounds necessarily imperfect, and their names are therefore subject to correction, as new facts may be obtained. The more noteworthy modern genera included in the Dakota flora, as catalogued by Lesquereux, are the follow- ing ; Liquidambar, the sweet-gum, is represented both in America and Europe, the leaves resembling those of the modern species, but with entire edges, which seems to be a common peculiarity of Cretaceous foliage.* Populus (poplar), as already stated, appears very early in Green- land, and continues with increasing number of species throughout the Cretaceous and Tertiary. Salix (willow) appears only a little later and continues. Of the family CupnUferm we have Fayus (beech), Quercus (oak), and Castanea (chestnut), which appear together in the Dakota group and its equivalents. Fruits of some of the species are known, and also wood showing structure. Bctula * With reference to this, somethinf; may be learned from the leaves of modern trees. In these, young shoots have leaves often less toothed and serrated than those of the adult tree. A remarkable instance is the Poj.ulns grandidcntatnH of America, the young shoots of which have en- tire leaves, quite unlike except in venation those of the parent tree, aud having an aspect very similar to that of the Cretaceous poplars. m ' i \ 198 TUE GEOLOGICAL HISTORY OF PLANTS. m 1 '! H I J ' 11 I 'i (birch) is representor! by a few species, and specimens of its peculiar bark are also common. Alnus (alder) ap- pears in one species at least. The genus Platanus (Fig. 71), that of the plane-trees, represented at present by one Fio. 71. — Platanus nobilis. Newberry, variety baailobata. Laramie. Much reduced. European and one American species, has several species in the Cretaceous, though the plane-trees seem to culmi- nate in the early part of the succeeding Eocene, where there are several species with immense leaves. The large '«*•-* «r ^ «^ 'Av* I 11 1 LATER CRETACEOUS AND KAINOZOIC. 199 3f le leaves, known as Credneria, found in tlie Cenomanian of Europe, and those called Protophyllum (Fig. 72) in America, appear to be nearer to the plane-trees than to any others, though representing an extinct type. The laurels are represented in this age, and the American genus Sassafras, which has now only one species, has not one merely but several species in the Cretaceous. Diofi- pyros, the persimmon-tree, was also a Cretaceous genus. FiQ. *12,— Protophyllum boreale, Dawson, reduced. Upper Cretaceous, Cauada. The single species of the beautiful Liriodendron, or tulip- tree, is a remnant of a genus which had several Cretaceous species (Figs. 74, 75). The magnolias, still well repre- sented in the American flora, were equally plentiful in the Cretaceous (Fig. 73). The walnut family were well repre- sented by species of Juglans (butternut) and Gary a, or hickory. In all, no less than forty-eight genera are pres- ent belonging to at least twenty-five ' Mes, running through the whole range of the dicotyU jus exogens. This is a remarkable result, indicating a suaden profusion ■iM! ■lii.. ;' 1 I \. Si i: 200 THE GEOLOGICAL HISTORY OF PLANTS. i'i : forms of these plants of a very striking character. It .s further to be observed that some of the genera have many species in the Cre- taceous and dwindle to- ward the modern. In others the reverse is the case — they have expand- ed in modern times. In a number there seems to have been little change. Dr. Newberry has given, in the ''Bulletin of the Torrey Botanical Club," an interesting resume of the history of the beautiful Lirio- dendron, or tulip-tree, which may be taken as an example of a genus which has gone down in importance in the course of its geological history. "The genus Lirio- dendron, as all botan- ists know, is represent- ed in the present flora by a single species, * the tulip-tree,' which is con- fined to eastern Amer- ica, but grows over all the area lying between the Lakes and the Gulf, the Mississippi and the Atlantic. It is a mag- nificent tree, on the r Fio. 73. — Maqnolia magnifica^ Dawson, reduced. iJpper Cretaceoua, Canada. r !; LATER CRETACEOUS AND KAINOZOIC. 9,01 whole, the finest in our forests. Its cylindrical trunk, sometimes ten feet in diameter, carries it beyond all its associates in size, while the beauty of its glossy, lyre- shaped leaves and tulip- like flowers is only sur- passed by the flowers and foliage of its first cous- in, Magnolia grandiflora. That a plant so splendid Fio. 74. — Liriodendron Meekii^ Ileer. (After Lesqucrtux.) Fio. 75. — Liriodendron primccvum^ Newberry. (After Newberry.) should stand quite alone in the vegetation of the present day excited the wonder of the earlier botanists, but the sassafras, the sweet-gum, and the great Sequoias of the far West afford similar examples of isolation, and the latter are still more striking illustrations of solitary grandeur." (Figs. 74 and 75.) ** Three species of Liriodendron are indicated by leaves found in the Amboy clays — Middle Cretaceous — of New Jersey, and others have been obtained from the Dakota group in the West, and from the Upper Cretaceous strata of Greenland. Though differing considerably among themselves in size and fv-rm, all these have the deep sinus of the upper extremity so characteristic of the genus, and the nervation is also essentially the same. Hence, we must conclude that the genus Liriodendron, now rep- .19 '.I !i!i ■ ! , ' 111* < 1 It m !:■ 202 THE GEOLOGICAL HISTORY OF PLANTS. resented by a single species, was in the Cretaceouii age much more largely developed, having many species, and those scattered throughout mary lands. In the Tertiary age the genus continued to exist, but the species seem to have been reduced to one, which is hardly to be distin- guished from that now living. In many parts of Europe leaves of the tulip-tree have been found, and it extended as far south as Italy. Its presence there was first made known by Unger, in his ' Synopsis,' page 233, and in his * Genera et Species,' page 443, where he describes it under the name of Liriodendron procaccinii. Tlie genus has also been noticed in Europe by Massalongo, Ileer, and Ettingshausen, and three species have been distinguished. All these are, however, so much like the living species that they should probably be united with it. We here have a striking illustration of the wide distribution of a species which has retained its characters both of fruit and leaf quite unchanged through long migrations and an enormous lapse of time. "■ In Europe the tulip-tree, like many of its American associates, seems to have been destroyed by the cold of the Ice period, the Mediterranean cutting off its retreat, but in America it migrated southward over the southern extension of the continent and returned northward again with the amelioration of the climate." Leaves of Liriodendron have been recognised in the Cretaceous of Greenland, though it is now a tree of the warm temperate region, and Lesquereux describes several species from the Dakota group. But the genus has not yet been recognised in the Laramie or in the Upper Cretaceous of British Columbia. In the paper above quoted, Newberry describes three new species from the Amboy clays, one of which he considers iden- tical with a Greenland form referred by Heer to L. Meeki of the Dakota group. Thus, if all Lesque- reux's species are to be accepted, the genus begins LATER CRETACEOUS AND KAINOZOiC. 203 in the Middle Cretaceous with at least nine American species. In New Jersey the Amboy clays are referred to the same age with the Dakota beds of the West. In these Dr. Newberry has found a rich flora, including many angiosperms. The following is condensed from a pre- liminary notice in the " Bulletin of the Torrey Botanical Club":* *' The flora of the Amboy clays is closely related to that of the Dakota group — most of the genera and some of the species being identical — so that we may conclude they were nearly contemporaneous, though the absence in New Jersey of the Fort Benton and Niobrara groups of the upper Missouri and the apparent synchronism of the New Jersey marls and the Pierre group indicate that the Dakota is a little the older. ** At least one-third of the species of the Amboy clays seem to be identical with leaves found in the Upper Cre- taceous clays of Greenland and Aachen (Aix la Chapelle), which not only indicates a chronological parallelism, but shows a remarkable and unexpected similarity in the vege- tation of these widely separated countries in the middle and last half of the Cretaceous age. The botanical char- acter of the flora of the Amboy clays will be seen from the following brief synopsis : " AlgcB. — A small and delicate form, allied to Chon- drites. *' Ferns. — Twelve species, generally similar and in part identical with those described by Heer from the Cretaceous beds of Greenland, and referred to the genera Dicksonia, Gleichenia, and Aspidium. " Cycads. — Two species, probably identical with the forms from Greenland described by Ileer under the names of Podozamitcs marginatus and P. tenuinervis. * March, 1886. ■I Ml :? ll 204 THE GEOLOGICAL HISTORY OF PLANTS. ** Conifers. — Fourteen species, belonging to the genera Moriconia, Brachyphyllum, Cunninghamites, Pitius, Se- quoia, and others referred by Heer to Juniperus, Libo- cedruSy Frenelopsis, Thuya, and Dammara. Of these, the most abundant and most interesting are Moriconia cyclotoxon — the most beautiful of conifers — and Cunning- hamites elegans, both of which occur in the Cretaceous clays of Aachen, Prussia, and Patoot, Greenland. The Brachyphyllum was a large and strong species, with im- bricated cones, eight inches in length. " The angiosperms form about seventy species, which include three of Magnolia, four of Liriodendron, three or four of Salix, three of Celastrophyllum (of which one is identical with a Greenland species), one Celastrus (also found in Greenland), four or five Aralias, two Sassafras, one Cinnamomum, one Hedera j with leaves that are ap- parently identical with those described by Heer as belong- ing to Andromeda, Cissiies, Cornus, Dewalquea, Dios- pyros, EucalyiAus, Ficus, Ilex, Juglans, Laurus, Meiii- spermites, Myrica, Myrsine, Prunus, Rhamnus, and others not yet determined. *' Some of the Aralias had palmately-lobed leaves, nearly a foot in diameter, and two of the tulip-trees {Liriodendron) had leaves quite as large as those of the living species. One of these had deeply lobed leaves, like those of the white oak. Of the other, the leaves resem- bled those of the recent tulip-tree, but were larger. Both had the peculiar emargination and the nervation of Lirio- dendron. ** Among the most interesting plants of the collection are fine species of Bauhinia and Hymenwa. Of these, the first is represented by a large number of leaves, some of which are six or seven inches in diameter. They are deeply bilobed, and have the peculiar and characteristic form and nervation of the leaves of this genus. Bauhi- nia is a leguminous genus allied to Cercis, and now in- 1 LATER CRETACEOUS AND KAINOZOIC. 205 habits tropical and warm temperate climates in both hemispheres. Only one species occurs in the United States, Bauhinia lunarioides, Gray, found by Dr. Bige- low on the Rio Grande. '* Ilymenma is anotlier of the leguminosa), and inhab- its tropical America. A species of this genus has been found in the Upper Cretaceous of France, but quite dif- ferent from the one before us, in which the leaves are much larger, and the leaflets are united in a common petiole, which is winged ; this is a modification not found in the living species, and one which brings it nearer to Bauhinia. ** But the most surprising discovery yet made is that of a number of quite large helianthoid flowers, which I have called Palmanthus. These are three to four inches in diameter, and exhibit a scaly involucre, enclosing what much resembles a fleshy receptacle with achenia. From the border of this radiate a number of ray florets, one to two inches in length, which are persistent and must have been scarious, like those of Hclichrysum. Though these flowers so much resemble those of the compositsB, we are not yet warranted in asserting that such is certainly their character. In the Jurassic rocks of Europe and India some flowers not very unlike these have been found, which have been named WilUamsonia, and referred to cycads by Carruthers. A similar fossil has been found in the Cre- taceous rocks of Greenland, and named by Ileer WilUam- sonia cretacea, but he questions the reference of the genus to the Cycadese, and agrees with Nathorst in considering all the species of WilUamsonia as parasitic flowers, allied to Brugmansia or Rafflesia. The Marquis of Saporta regards them as monocotyledons, similar to Pandanus. More specimens of the flowers now exhibited will perhaps prove — what we can now only regard as probable — that the Compositae, like the Leguminosm, Magnoliacem, Ce- lastracecB, and other highly organised plants, formed part 'Ml TT i 1 t|K I 1 i ' ! 206 THE GEOLOGICAL HISTORY OF PLANTS. of the Cretaceous flora. No composite flowers have be- fore been found in the fossil state, and, as these are among the most complex and specialised forms of florescence, it has been supposed that they belonged only to the recent epoch, where they were the result of a long series of form- ative changes." The above presents some interesting new types not heretofore found in the Middle Cretaceous. More espe- cially the occurrence of large flowers of the composite type presents a startling illustration of the early appear- ance of a very elevated and complex form. Great interest also attaches to these Amboy beds, as serving, with those of Aix and Greenland, to show that the margins of the Atlantic were occupied with a flora similar to that occur- ring at the same time in the interior plateau of North America and on the Pacific slope. The beds at Aix-la-Chapelle are, however, probably somewhat newer than the Dakota or Amboy beds, and correspond more nearly in age with those of the Creta- ceous coal-field of Vancouver Island, where there is a very rich Upper Cretaceous flora, which I have noticed in de- tail in the *' Transactions of the Royal Society of Cana- da."* In these Upper Cretaceous beds there are fan- palms as far north at least as the latitude of 49°, indicat- ing a very mild climate at this period. This inference is corroborated by the Upper Cretaceous flora of Atane and Patoot in Greenland, as described by Heer. The dicotyledonous plants above referred to are trees and shrubs. Of the herbaceous exogens of the period we know less. Obviously their leaves are less likely to find their way into aqueous deposits than the leaves of trees. They are, besides, more perishable, and in densely wooded countries there are comparatively few herbaceous plants. I have examined the beds of mud deposited at the mouth ♦Vol. ii., 1884. LATER CRETACEOUS AND KAIXOZOIC. 207 of a woodland streamlet, and have found them stored with the fallen leaves of trees, but it was in vain to search for the leaves of herbaceous plants. The climate of North America and Europe, represented by the Cenomanian vegetation, is not tropical but warm temperate ; but the flora was more uniform than at pres- ent, indicating a very equable climate and the possibility of temperate genera existing within the Arctic circle, and it would seem to have become warmer toward the close of the period. The flora of the Cenomanian is separated in most countries from that of the Senonian, or uppermost Cre- taceous, by a marine formation holding few plants. This depends on great movements of elevation and depression, to which we must refer in the sequel. In a few regions, however, as in the vicinity of the Peace River in Canada, there are plant-bearing beds which serve to bridge over the interval between the Early Cenomanian and the later Cretaceous.* To this interval also would seem to belong the Belly River series of western Canada, which contains important beds of coal, but is closely as- sociated with the marine Fort Pierre Mcries. A very curious herbaceous plant of this group, which I have named Brasenia an- tiqua, occurs in the beds associated with one of the coals. It is a close ally of the modern B. peltata, an aquatic plant which occurs in British Columbia and in eastern Fio. 7*5. — Brasenia antiqua. Upper Cre- taceous, South Saskatchewan River. Natural size, a, A, Diagrams of vena- tion, sliglitly enlarged. * See paper by the author in the " Transactions of the Koyal Society of Canada," 1882. 208 TUE GEOLOGICAL HISTORY OF PLANTS. America, and is also said to be found in Japan, Australia, and India, a width of distribution appropriate to so old a type (Fig. 70). In so far as vef^etable life is concerned, the transition from the Upper Cretaceous to the Tertiary or Kainozoio is easy, though in many parts of the world, and more especially in western Europe, there is a great gap in the deposits between the upper Chalk and the lowest Eocene. With reference to fossil plants, Schimper recognises in the Kainozoic, beginning with the oldest, five formations — Pala3ocene, Eocene, Oligocone, Miocene, and Pliocene. Throughout these a flora, similar to that of the Creta- ceous on the one hand and the modern on the other, though with important local peculiarities, extends. There is evidence, however, of a gradual refrigeration, so that in the Pliocene the climates of the northern hemisphere were not markedly different from their present character. In the first instance an important error was com- mitted by palaeobotanists, in referring to the Miocene many deposits really belonging to the Eocene. This arose from the early study of the rich plant-bearing Miocene beds of Switzerland, and from the similarity of the flora all the way from the Middle Cretaceous to the later Tertiary. The differences are now being worked out, and we owe to Mr. Starkie Gardner the credit of pointing these out in England, and to the Geological Survey of Canada that of collecting the material for exhibiting them in the more northern part of America. In the great interior plain of America there rests on the Cretaceous a series of clays and sandstones with beds of lignite, some of them eighteen feet in thickness. This was formerly known as the lignitic or lignite Ter- tiary, but more recently as the Laramie series. These beds were deposited in fresh or brackish water, in an internal sea or group of lakes and swamps, when the continent was lower than at present. They have been .^4»»i»/l »•' LATER CRETACEOUS AND KALVOZOIC. 209 studied both in the United States ♦ and Canada ; and, though tiieir flora was originally referred by mistake to the Miocene, it is now known to be Eocene or Paloeocene, or even in part a transition group between the latter and the Cretaceous, 'i'lie following remarks, taken chiefly from recent papers by the author, f will serve to illustrate this : On the geological map of Canada the Laramie series, formerly known as the lignitic or lignite Tertiary, oc- curs, with the exception of a few outliers, in two large areas west of the 100th meridian, and separated from each other by a tract of older Cretaceous rocks, over which the Laramie beds may have extended, before the later denuda- tion of the region. The most eastern of these areas, that of the Souris River and Wood Mountain, extends for some distance along the United States boundary, between the 102d and 109th meridians, and reaches northward to about thirty miles south of the ** elbow" of the South Saskatchewan River, which is on the parallel of 51° north. In this area the lowest beds of the Laramie are seen to rest on those of the Fox Hill group of the Upper Cretaceous, and at one point on the west they are overlaid by beds of Miocene Tertiary age, observed by Mr. McConnell, of the Geological Survey, in the Cypress Hills, and referred by Cope, on the evidence of mammalian remains, to the White River division of the o'nited States geologists, which is regarded by them as Lower Miocene.| The age of the Laramie beds is thus stratigraphically determined to be between the Fox Hill Cretaceous and the Lower * See more especially the elaborate and valuable reports by Lesque- reux and Newberry, and a recent memoir by Ward on " Types of the Laramie Flora," " Bulletins of the United States Geological Survey," 1887. f "Transactions of the Royal Society of Canada," 188G-'87. \ " Report of the Geological Survey of Canada," 1888. 210 TUE GEOLOGICAL HISTORY OF PLANTS. I i Miocene. They are also undoubtedly continuous with the Fort Union group of the United States geologists on the other side of the international boundary, and they contain similar fossil plants. They are divisible into two groups — a lower, mostly argillaceous, and to which the name of ^' Bad Lands beds " mny be given, from the "bad lands" of Wood Mountain, where they are well exposed, and an upper, partly arenaceous member, which may be named tiie Souris River or Porcupine Creek division. In the lower division are found reptilian remains of Upper Cretaceous type, with some fish remains more nearly akin to those of the Eocene.* Neither division has as yet afforded mammalian remains. The western area is of still larger dimensions, and ex- tends along the eastern base of the Rocky Mountains from the United States boundary to about the 55th parallel of latitude, and stretches eastward to the 111th meridian. In this area, and more especially in its southern part, the officers of the Geological Survey of Canada have recog- nised three divisions, as follows : (1) The Lower Laramie or St. Mary River series, corresponding in its character and fossils to the Lower or Bad Lands division of the other area. (2) A middle division, the Willow Creek beds, consisting of clays, mostly reddish, and not recog- nised in the other area. (3) The Upper Laramie or Porcupine Hills division, corresponding in fossils, and to some extent in mineral character, to the Souris River beds of the eastern area. The fossil plants collected by Dr. G. M. Dawson in the eastern area were noticed by the author in an appen- dix to Dr. Dawson's report on the 49th parallel, in 1875, and a collection subsequently made by Dr. Selwyn was described in the ** Report of the Geological Survey of Cauada" for 1879-80. Those of the western area, and * Cope, in Dr. G. M. Dawson's " Report on the 49th Parallel." ?i LATER CRETACEOUS AND KAINOZOIC. 211 of id especially collections made by myself near Calgary in 1883, and by officers of the Geological Survey in 1884, have been described in the "Transactions of the Royal Society of Canada," vols. iii. and iv. In studying these fossil plants, I have found that there is a close correspondence between those of tiie Lower and Upper Laramie in the two areas above re- ferred to respectively, and that the flora of the Lower Laramie is somewhat distinct from that of the Upper, the former being especially rich in certain aquatic plants, and the latter much more copious on the whole, and much more rich in remains of forest-trees. This is, how- ever, possibly an effect rather of local conditions than of any considerable change in the flora, since some Upper Laramie forms recur as low as the Belly River series of the Cretaceous, which is believed on stratigraphical grounds to be considerably older than the Lower Laramie. With reference to the correlation of these beds with those of the United States, some difficulty has arisen from the tendency of palaeobotanists to refer the plants of the Upper Laramie to the Miocene age, although in the re- ports of Mr. Clarence King, the late director of the United States Geological Survey, these beds are classed, on the evidence of stratigraphy and animal fossils, as Upper Cretaceous. More recently, however, and partly perhaps in consequence of the views maintuined by the writer since 1875, some change of opinion has occurred, and Dr. Newberry and Mr. Lescpiereux seem now in- clined to admit that what in Canada we recognise as Upper Laramie is really Eocene, and the Lower Laramie either Cretaceous or a transition group between this and the Eocene. In a recent paper * Dr. Newberry gives a comparative table, in which he correlates tiie Lower * Newberry, " Transactions of the New York Academy," February, 1886. 212 THE GEOLOGICAL HISTORY OF PLANTS. I i li I Laramie with the Upper Cretaceous of Vancouver Island and the Faxoe and Maestricht beds of Europe, while he regards the Upper Laramie as equivalent to European Eocene. Excej^t in so far as the equivalence of the Lower Laramie and Vancouver Island beds is concerned, this corresponds very nearly witli the conclusions of the writer in a paper published last year * — namely, that we must either regard the Laramie as a transition Cretaceo- Eocene group, or must institute our line of separation in the Willow Creek or Middle Laramie division, which has, however, as yet afforded no fossil plants. I doubt, how- ever, the equivalence of the Vancouver beds and the Lower Laramie, except erhaps in so far as the upper member of the former is concerned. I have also to ob- serve that in the latest report of Mr. Lesquereux he still seems to retain in the Miocene certain formations in the West, which from their fossil plants I should be inclined to regard as Eocene, f Two ferns occurring in these beds are remarkable as evidence of the persistence of species, and of the pecul- iarities of their ancient and modern distribution. Onoclea sensibilis, the very common sensitive fern of eastern America, is extremely abundant in the Laramie beds over a great area in the West. Mr. Starkie Gardner and Dr. Newberry have also shown that it is identical with the Filicites Hehridicus of Forbes, from the early Eocene beds of the Island of Mull, in Scotland. Thus we have a species once common to Europe and America, but now restricted to the latter, and which has continued to exist over all the vast ages between the Cretaceous and the present day. In the Laramie beds I have found asso- * " Transactions of the Royal Society of Canada," vol. ii. f While these sheets were going through the press I receivecl a very valuable report of Mr. Lester F. Ward upon the Laramie of the United States. I have merely had time to glance at this report, but can see that the views of the author agree closely with those above expressed. LATER CRETACEOUS AND KAINOZOIC. 213 ciated with this species another and more delicate fern, the modern DavalUa {Stenloma) tenuifoUa, but this, un- like its companion, no longer occurs in America, but is found in the mountains of Asia. This is a curious illus- tration of the fact that frail and delicate plants may be more ancient than the mountains or plains on which they live. There are also some very interesting and curious facts in connection with the conifers of the Laramie. One of the most common of these is a Thuja or arbor vitae (the so-called "cedar" of Canada). The Laramie species has been named T. interrupta by Newberry, but it approaches very closely in its foliage to T. occidentalism of eastern Canada, while its fruit resembles that of the western species, T. gigantea. Still more remarkable are the Sequoias to which we have already referred, but which in the Laramie age seem to have been spread over nearly all North America. The fossil species are of two types, repreeenting respectively the modern S. gigantea and 8. sempervirens, and their wood, as well as that of Thuja, is found in great abun- dance in the lignites, and also in tlie form of silicified trunks, and corresponds with that of the recent species. The Laramie contains also conifers cf the genera Glypto- strohus, Taxodium, and Taxus ; and the genus Salishuria or gingko — so characteristic of the Jurassic and Creta- ceous— is still represented in America as woU as in Europe in the early Eocene. We have no palms in the Canadian or Scottish Paloeo- cene, though I belicTe they are found further south. The dicotyledonous trros are richly repre'^f^nted. Perhaps the most conspi'iious v ere three spt" les of Platanus, the leaves of which sometimes fill the sandstones, and one of which, P. nobilisy dewberry, sometimes attains the gi- gantic size of a foot or more in diameter of its blade. The hazels are represented by a large-leaved species, C. 20 m 214 THE GROLOGICia HISTORY OF PLANTS. 1 ;.| ;! Macquarii, and by leaves ^lot distinguishable from those of the modern American ecies, 6'. Americana and C. rostrata. There are also chestnuts and oaks. But the poplars and willows are specially abundant, being repre- sented by no less than six species, and it would seem that all the modern types of poplar, as indicated by the forms and venation of the leaves, existed already in the Laramie, and most of them even in the Upper Cretaceous. Sassafras is represented by two species, and the beautiful group of Viburnum, to which the modern tree-cranberry belongs, has several fine species, of some of which both leaves and berries have been found. The hickories and butternuts are also present, the horse-chestnut, the Ca- talpa and Sapindus, and some curious leaves which seem to indicate the presence of the modern genus Symplwro- carpus, the snow-berry tribe. The above may suffice to give an idea of the flora of the older Eocene in North America, and I may refer for details to the works of Newberry, Lesquereux, and Ward, already cited. I must now add that the so-called Mio- cene of Atanekerdluk, Greenland, is really of the same age, as also the "Miocene" of Mull, in Scotland, of i « Antrim, in Ireland, and of Bovey Tracey, in the south of England, and the Gelinden, or " Heersian " beds, of Bel- gium, described by Saporta. In comparing the American specimens with the descriptions given by Gardner of the leaf-beds at Ardtown, in Mull, we find, as already stated, Onoclea sensihilis, common to both. The species of Sequoia, Gingico, Taxus, and Glyptostrohus are also iden- tical or closely allied, and so are many of the dicotyledo- nous leaves. For example, Platanoides Hehridicus is very near to P. nobilis, and Gorylus Macquarrii is com- mon to both formations, as well as Populus Arctica and P. Richtirdsoni. I may add that ever sincu 1 875-76, when I first studied the Laramie plants, I have main- tained their identity with those of the Fort Union group LATER CRETACEOUS AND KAINOZOIC. 215 of the United States, and of the. so-called Miocene of McKeuzie River and Greenland, and that the whole are Paleocene ; and this conclusion has now been confirmed by the researches of Gardner in England, and by the dis- covery of true Lower Miocene beds in the Canadian north- west, overlying the Laramie or lignite series. In a bulletin of the United States Geological Sur- vey (1886), Dr. White has established in the AVest the continuous stratigraphical succession of the Laramie and the Wahsatch Eocene, thus placing the Laramie con- formably below the Lower Eocene of that region. Cope has also described as the Puerta group a series of beds holding vertebrate fossils, and forming a transition from the Laramie to the "Wahsatch. White also testifies that a number of fresh-water mollusks are common to the Wah- satch and the Laramie. This finally settles the position of the Laramie so far as the United States geologists are concerned, and shows that the flora is to be regarded as Eocene if not Upper Cretaceous, in harmony with what has been all along maintained in Canada. An important resume of the flora has just been issued by Ward in the bulletins of the United States Geological Survey (1887). Before leaving this part of the subject, I would depre- cate the remark, which I see occasionally made, that fossil plants are of little value in determining geological hori- zons in the Cretaceous and Tertiary. I admit that in these periods some allowance must be made for local differences of station, and also that there is a generic sameness in the flora of the northern hemisphere, from the Cenomanian to the modern, yet these local differ- ences and general similarity are not of a nature to in- validate inferences as to age. No doubt, so long as palfEobotanists seemed obliged, in deference to authority, and to the results of investigations limited to a few Eu- ropean localities, to group together, without distinction, all the floras of the later Cretaceous and earlier Tertiary, J li 1 f !. ' : 3 " " 216 THE GEOLOGICAL HISTORY OF PLANTS. irrespective of stratigraphical considerations, the subject lost its geological importance. But, when a good series has been obtained in any one region of some extent, the case becomes different. Though there is still much im- perfection in our knowledge of the Cretaceous and Ter- tiary floras of Canada, I think the work already done is sufficient to enable any competent observer to distinguish by their fossil plants the Lower, Middle, and Upper Cre- taceous, and the latter from the Tertiary ; and, with the aid of the work already done by Lesquereux and New- berry in the United States, to refer approximately to its true geological position any group of plants from beds of unknown age in the West. An important consequence arising from the above statements is that the period of warm climate which enabled a temperate flora to exist in Greenland was that of the later Cretaceous and early Eocene rather than, as usually stated, the Miocene. It is also a question admit- ting of discussion whether the Eocene flora of latitudes so different as those of Greenland, Mackenzie River, north- west Canada, and the United States,-were strictly con- temporaneous, or successive within a long geological period in which climatal changes were gradually pro- ceeding. The latter statement must apply at least to the beginning and close of the period ; but the plants themselves have something to say in favour of contem- poraneity. The flora of the Laramie is not a tropical but a temperate flora, showing no doubt that a much more equable climate prevailed in the more northern parts of America than at present. But this equability of climate implies the possibility of a great geographical range on the part of plants. Thus it is quite possible and indeed highly probable that in the Laramie age a somewhat uniform flora extended from the Arctic seas through the great central plateau of America far to the south, and in like manner along the western coast of LATER CRETACEOUS AND KAINOZOIC. 217 Euroi:>c. It is also to be observed that, as Gardner points out, theie are some differences indicating a diversity of climate between Greenland and England, and even be- tween Scotland and Ireland and the south of England, and we have similar differences, though not strongly marked, between the Laramie of northern Canada and that of the United States. When all our beds of this age from the Arctic sea to the 49th parallel have been ransacked for plants, and when the palseobotanists of the United States shall have succeeded in unravelling the confusion which now exists between their Laramie and the Middle Tertiary, the geologist of the future will be able to restore with much certainty the distribution of the vast forests which in the early Eocene covered the now bare plains of interior America. Further, since the break which in western Europe separates the flora of the Cretaceous from that of the Eocene does not exist in America, it will then be possible to trace the succession from the Mesozoic flora of the Trias and of the Queen Charlotte Islands and Kootanie series of the Lower Cre- taceous up to the close of the Eocene ; and to deter- mine, for America at least, the manner and conditions under which the angiospermous flora of the later Creta- ceous succeeded to the pines and cycads which charac- terised the beginning of the Cretaceous period. In so far as Europe is concerned, this may be more difficult, since the want of continuity of land from ni h to south seems there to have been fatal to the continu, ice of some plants during changes of climate, and there were also apparently in the Kainozoic period invasions at certain times of species from the south and east, which did not occur to the same extent in America. In recent reports on the Tertiary floras of Australia and New Zealand,* Ettingshausen holds that the flora of ll'i « (i Geological Magazine," August, 1887. w M 11 ' • 11 f f 1 i I I 21P THE GEOLOGICAL HISTORY OF PLANTS. t^ tiary, as a whole, was of a generalised character ; i now confined to the southern and northern hemi- xcres respectively being then common to both. It would thus seem that the present geographical diversities must have largely arisen from the great changes in cli- mate and distribution of land and water in the later Tertiary. The length of our discussion of the early angiosperm- ous flora does not permit us to trace it in detail through the Miocene and Pliocene, but we may notice the con- nection through these in the next chapter, and may refer to the magnificent publications of Heer and Lesquereux on the Tertiary floras of Europe and America respect- ively. CHAPTER VII. PLANTS FROM THE TERTIARY TO THE MODERN PERIOD. It may be well to begin this chapter with a sketch of the general physical and geological conditions of the pe- riod which was characterised by the advent and culmina- tion of the dicotyledonous trees. In the Jurassic and earliest Cretaceous periods the prevalence, over the whole of the northern hemisphere and for a long time, of a monotonous assemblage of gym- nospermous and acrogenous plants, implies a uniform and mild climate, and facility for intercommunication in the north. Toward the end of the Jurassic and beginning of the Cretaceous, the land of the northern hemisphere was assuming greater dimensions, and the climate probably becoming a little less uniform. Before the close of the Lower Cretaceous period the dicotyledonous flora seems to have been introduced, under geographical conditions which permitted a warm temperate climate to extend as far north as Greenland. In the Cenomanian or Middle Cretaceous age we find the northern hemisphere tenanted with dicotyledonous trees closely allied to those of modern times, though still indicating a climate much warmer than that which at present prevails. In this age, extensive but gradual sub- mergence of land is indicated by the prevalence of chalk and marine limestones over the surface of both conti- nents; but a circumpolar belt seems to have been main- tained, protecting the Atlantic and Pacific basins from ■\1 'H 1' ! I' l> m- I! i 220 THE GEOLOGICAL F^STORY OP PLANTS. floating ico, and permitting a temperate flora of great richness to prevail far to the north, and especially along the southern margins and extensions of the circumpolar land. These seem to have been the physical conditions which terminated the existence of the old Mesozoic flora and introduced that of the Middle Cretaceous. As time advanced the quantity of land gradually in- creased, and the extension of new plains along the older ridges of land was coincident with the deposition of the great Laramie series, and with the origination of its pe- culiar flora, which indicates a mild climate and consider- able variety of station in mountain, plain, and swamp, as well as in great sheets of shallow and weedy fresh water. In the Eocene and Miocene periods, the continents gradually assumed their present form, and the vegetation became still more modern in aspect. In that period of the Eocene, however, in which the great nummulitic limestones were deposited, a submergence of land occurred on the eastern continent which must have assimilated its physical conditions to those of the Middle Cretaceous. This great change, affecting materially the flora of Eu- rope, was not equally great in America, which also by the north and south extension of its mountain-chains per- mitted movements of migration not possible in the Old World. From the Eocene downward, the remains of land-animals and plants are found chiefly in lake-basins occupying the existing depressions of the land, though more extensive than those now remaining. It must also be borne in mind that the great foldings and fractures of the crust of the earth which occurred at the close of the Eocene, and to which the final elevation of such ranges as the Alps and the Rocky Mountains belongs, perma- nently modified and moulded the forms of the continents. These statements raise, however, questions as to the precise equivalence in time of similar floras found in dif- THE TKRTIARY TO THE MODERN PERIOD. 221 ferent lutitudes. However equable the climate, there must have been some appreciable difference in proceed- ing from north to south. If, therefore, as seems in every way probable, the new species of plants origi- nated on the Arctic land and spread themselves south- ward, this latter process would occur most naturally in times of gradual refrigeration or of the access of a more extreme climate — that is, in times of the elevation of land in the temperate latitudes, or, conversely, of local depression of land in the Arctic, leading to invasions of northern ice. Hence, the times of the prevalence of particular types of plants in the far north would precede those of their extension to the south, and a flora found fossil in Greenland might be supposed to be somewhat older than a similar flora when found farther south. It would seem, however, that the time required for the ex- tension of a new flora to its extreme geographical limit is so small, in comparison with the duration of an entire geological period, that, practically, this difference is of little moment, or at least does not amount to antedating the Arctic flora of a particular type by a whole period, but only by a fraction of such period. It does not appear that, during the whole of the Cre- taceous and Eocene periods, there is any evidence of such refrigeration as seriously to interfere with the flora, but perhaps the times of most considerable warmth are those of the Dunvrgan group in the Middle Cretaceous, and those of the later Laramie and oldest Eocene. It would appear that no cause for the mild tempera- ture of the Cretaceous needs to be invoked, other than those mutations of land and water which the geological deposits themselves indicate. A condition, for example, of the Atlantic basin in which the high land of Greenland should be reduced in elevation, and at the same time the northern inlets of the Atlantic closed against the invasion of Arctic ice, would at once restore climatic conditions II II m 222 THE GEOLOGICAL HISTORY OF PLANTS. allowing of the growth of a temperate flora in Greenland. As Dr. Brown has shown,* and as I have elsewhere argued, the absence of light in the Arctic winter is no disadvantage, since, during the winter, the growth of deciduous trees is in any case suspended ; while the con- stant continuance of light in the summer is, on the con- trary, a very great stimulus and advantage. It is a remarkable phenomenon in the history of gen- era of plants in the later Mesozoic and Tertiary, that the older genera appear at once in a great number of specific types, which become reduced as well as limited in range down to the modern. This is, no doubt, connected with the greater differentiation of local conditions in the mod- ern ; but it indicates also a law of rapid multiplication of species in the early life of genera. The distribution of the species of Salisburittj Sequoia, Platanus, Sassafras, Lirio- dendron, Magnolia, and many other genera, affords re- markable proofs of this. Gray, Saporta, Ileer, Newberry, Lesqncreux, and Starkie Gardner have all ably discussed these points ; but the continual increase of our knowledge of the several floras, and the removal of error as to the dates of their appearance, must greatly conduce to clearer and more definite ideas. In particular, the prevailing opinion that the Miocene was the period of the greatest extension of warmth and of a temperate flora into the Arctic, must be abandoned in favour of the later Cretaceous and Eocene ; and, if I mistake not, this will be found to ac- cord better with the evidence of general geology and of animal fossils. In these various revolutions of the later Cretaceous and Kainozoic periods, America, as Dr. Gray has well pointed out, has had the advantage of a continuous stretch of high land from north to south, affording a more sure * t( Florula Discoana." TUE TERTIARY TO THE MODERN PERIOD. 223 refuge to plants in times of submergence, and means of escape to the south in times of refrigeration. Hence, the greater continuity of American vegetation and tlie survival of genera like Sequoia and Liriodendron, which have perished in the Old World. Still, there are some ex- ceptions to this, for the gingko-tree is a case of survival in Asia of a type once plentiful in America, but now extinct there. Eastern Asia has had, however, some considerable share of the same advantage possessed by America, with the addition, referred to by Gray, of a better and more insular climate. But our survey of these physical conditions can not be considered complete till we shall have considered the great Glacial age of the Pleistocene. It is certain that throughout the later Miocene and Pliocene the area of land in the northern hemisphere was increasing, and the largo and varied continents were tenanted by the noblest vege- tation and the grandest forms of mammalian life that the earth has ever witnessed. As the Pliocene drew to a close, a gradual diminution of warmth came on, and more especially a less equable climate, and this was ac- companied with a subsidence of the land in the temperate regions and with changes of the warm ocean-currents. Thus gradually the summers became cooler and the winters longer and more severe, the hill-tops became covered with permanent snows, glaciers ploughed their way downward into the plains, and masses and fields of floating ice cooled the seas. In these circumstances the richer and more delicate forms of vegetation must have been chilled to death or obliged to remove farther south, and in many extensive regions, hemmed in by the advance of the sea on the one hand and land-ice on the other, they must have altogether perished. Yet even in this time vegetation was not altogether extinct. Along- the Gulf of Mexico in America, and in the Mediterranean basin in Europe, there were still some "III' i 1 \h 11, i l][ i » 'W ! 1'! f^ ; I ■ t' 224 THE GEOLOGICAL HISTORY OF PLANTS. remains of a moderate climate and certain boreal and arctic forms moving southward continued to exist here and there in somewhat high latitudes, just as similar plants now thrive in Grinnell Land within sight of the snows of the Greenland mountains. A remarkable sum- mary of some of these facts as they relate to England was given by an eminent English botanist, Mr. Carruthers, in his address as President of the Biological Section of the British Association at Birmingham in 1886. At Cromer, on the coast of Norfolk, the celebrated forest-bed of new- er Pliocene age, and containing the remains of a copious mammalian fauna, holds also remains of plants in a state admitting of determination. These have been collected by Mr. Reid, of the Geological Survey, and were reported on by Carruthers, who states that they represent a some- what colder temperature than that of the present day. I quote the following details from the address. With reference to the plants of the forest-bed or newer Pliocene he remarks as follows : *' Only one species (Trapa nafans, Willd.) has disap- peared from our islands. Its fruits, which Mr. llcid found abundantly in one locality, agree with those of the plants found until recently in the lakes of Sweden. Four species (Prunus speciosa, L., Q^nanthe Tichenalii, Sm., Potamogeton pterophylhis, Sch., and Pinus abies, L.) are found at present only in Europe, and a fifth {Pota- mogeton triclioides, Cham.) extends also to North Ameri- ca ; two species (Peucedanum palustre, Moench, and Pinus sylvestris, L.) are found also in Siberia, while six more {Sanguisorha officinalis, L., Rubies fruticosus, L., Cornus sanguinm, L., Euphorbia amygdaloidcs, L., Quercus robur, L., and Potamogeton crispus, L.) extend into western Asia, and two {Fag us sylvatica, L., and Alnus glutinosa, L.) are included in the Japanese flora. Seven species, while found with the others, enter also into the Mediterranean flora, extending to North Africa : these THE TERTIARY TO THE MODERN PERIOD. 225 are Tlmlidrum minus, L., Tlialictrum jlavum, L., Ra- nunculus repots, L., iStellaria aquaiica, Scop., Corylus aveUana, L., Yajinichellia palustris, L., and Cladium mariscus, Br. With a similar distribution in the Old World, eight species {Bidens tripartita, L., Mijosotis ccBspitosa, Schultz, Suceda maritima, Dum., CWatophyl- lum demersu?n, L., Sparganium ramosum, Iluds., Pota- moyeton pectinatus, L., Carex paliidosa, Good., and Os- munda "^egalis, L.) are found also in North America. Of the remainder, ten species {Nuphar lutenm, Sm., Meny- anihes trifoliata, L., Stachys palustris, L., Rumex mari- timus, L., Rumex acetosella, L., Betula alba, L., Scirpus paucifiomis, Liglitf., Taxus baccata, L., and Isoetes la- custris, L. ) extend round the north temperate zone, while three {Lycopus europmus, L., Alisma plantago, L., and Phragmites communis, Trin.), having the same distribu- tion in the north, are found also in Australia, and one {Hippuris vulgaris, L.) in the south of South America. The list is completed by Ranunculus aquatilis, L., dis- tributed over all the temperate regions of the globe, and Scirpus lacustris, L., which is found in many tropical regions as well." • He remarks that these plants, while including species now very widely scattered, present no appreciable change of characters. Above this bed are glacial clays, which hold other species indicating an extremely cold climate. They are few in number, only Salix polaris, a thoroughly arctic species, and its ally, S. cinerea, L., and a moss, Hypiinm turgescens, Schimp., no longer found in Britain, but an Alpine and arctic species. This bed belongs to the begin- ning of the Glacial period, the deposits of which have as yet afforded no plants in England. But 4)lants occur in post-glacial and upper-glacial beds in different parts of T^erate flora of the Eocene ; so that here we have the evidence of fossil plants to show the change from the climate of the Eocene to that of arctic lands, and the modern vegetation to indicate the return of a warm temperature. THE TERTIARY TO THE MODERN PERIOD. 227 In Canada, in the Pleistocene beds known as the Leda clays, intervening between the lower boulder clay and the Saxicava sand, which also holds boulders, there are beds holding fossil plants, in some places intermixed with sea-shells and bones of marine fishes, showing that they were drifted into the sea at a time of submergence. These remains are boreal rather than arctic in character, and with the remains of drift-wood often found in the boulder deposits serve to indicate that there were at all times oases of hardy life in the glacial deserts, just as we find these in polar lands at the present day. I condense from a paper on these plants* the following facts, with a few additional notes : The importance of all information bearing on the temperature of the Post - pliocene period invests with much interest the study of the land-plants preserved in deposits of this age. Unfortunately, these are few in num- ber, and often not well preserved. In Canada, though fragments of the woody parts of plants occasionally occur in the marine clays and sands, there is only one locality which has afforded any considerable quantity of remains of their more perishable parts. This is the well-known deposit of Leda clay at Green's Creek, on the Ottawa, celebrated for the perfection in which the skeletons of the capelin and other fishes are preserved in the calcareous nodules imbedded in the clay. In similar nodnles, con- tained apparently in a layer somewhat lower than that holding the ichthyolites, remains of land-plants are some- what abundant, and, from their association with shells of Leda (jlacialis, seem to have been washed u^wn from the land into deep water. The circumstances would seem to have been not dissimilar from those at present existing in the northeast arm of Gaspe Basin, where I have dredged from mud now being deposited in deep water, living * "Canadian Naturalist," 1866. m 228 THE GEOLOGICAL HISTORY OF PLANTS. HI ir' I : specimens of Leda limatula, mixed with remains of land- plants. The following are the species of plants recognised in these nodules : 1. Drosera roHindifolia, Linn. In a calcareous nodule from Green's Creek, the leaf only preserved. This plant is common in bogs in Canada, Nova Scotia, and New- foundland, and thence, according to Hooker, to the Arctic circle. It is also European. 3. Acer spicatum, Lamx. {Acer montanum, Alton.) Leaf in a nodule from Green's Creek. Found in Nova Scotia and Canada, also at Lake Winnipeg, according to Richardson. 3. Potcntilla Ca?iadensif, Linn. In nodules from Green's Creek ; leaves only preserved. I have had some difficulty in determining these, but believe they must be referred to the species above named, or to P. simplex, Michx., supposed by Hooker and Gray to be a va- riety. It occurs in Canada and New England, but I have no in- formation as to its range north- ward. 4. Gaylussaccia resinosa, Tor- rey and Gray. Leaf in nodule at Green's Creek. Abundant in New England and in Canada, also on Lake Huron and the Saskatchewan, according to Richardson (Fig. 77). 5. Popiilus halsamifcra, Linn. Leaves and branches in nodules at Green's Creek. This is by much the most common species, and its leaves are of small size, as if from trees growing in cold and exposed situations. The species is North American and Asiatic, and abounds in New Eng- land and Canada. It extends to the Arctic circle, and is Fia. 77. — Oajilufisaccia resi- nosa. Pleistocene, Can- ada. THE TERTIARY TO THE MODERN PERIOD. 229 abundant on the shores of the Great Slave Lake and on tlie McKenzie River, and according to Richardson con- stitutes much of the drift timber of the Arctic coast (Fig. 78). 6. Thuja occidentalis, Linn. Trunks and branches in the Leda clay at Montreal. This tree occurs in New England and Canada, and extends northward into the Fig. 78. — Populus balsam i/era. Pleistocene, Canada. Hudson Bay territories. It is a northern though not arctic species in its geogra})hical range. According to Lyell it occurs associated with the bones of Mastodon in New Jersey. From the great durability of its wood, it is one of the trees most likely to be preserved in aqueous deposits. 7. Potamofjcton perfoliatus, Linn. Leaves and seeds in nodules at Green's Creek. Inhabits streams of the Northern States and Canada, and according to Richard- son extends to Great Slave Lake. 8. Potamogeton jmsUlus. Quantities of fragments which I refer to this species occur in nodules at Green's Creek. They may possibly belong to a variety of P. hybridus which, together with P. natans, now grows in 1 j: 1 \<: i ; ■ it 230 THE GEOLOGICAL HISTORY OF PLANTS. the river Ottawa, where it flows over the beds containing these fossils. 9. CaricecD and Graminem. Fragments in nodules from Green's Creek appear to belong to plants of these groups, but I cannot venture to determine their species. 10. Equisetum scirpoides, Michx. Fragments in nod- ules, Green's Creek. This is a widely distributed spe- cies, occurring in the Northern States and Canada. 11. Fontmalis. In nodules at Green's Creek there occur, somewhat plentifully, branches of a moss appar- ently of the genus Fon- tinalis. 12. AlgcB. With the plants above mentioned, both at Green's Creek and at Montreal, there occur remains of sea- weeds (Fig. 79). They seem to belong to the genera Fucus and Ulva^ but I cannot determine the species. A thick stem in one of the nod- ules would seem to indi- cate a large Laminaria. Fio. 79. — Frond of Fucus. Pleisto- cene, Cuniida. With the above there are found at Green's Creek a number of fragments of leaves, stems, and fruits, which I have not been able to refer to their species, principally on account of their defective state of preservation. None of the plants above mentioned is properly arctic in its distribution, and the assemblage may be character- ised as a selection from the present Canadian flora of some of the more hardy species having the most northern range. Green's Creek is in the central part of Canada, near to the parallel of 46°, and an accidental selection 'W THE TERTIARY TO TUE MODERN PERIOD. 231 from its present flora, though it might contain the same species found in the nodules, would certainly include with these, or instead of some of them, more southern forms. More especially the balsam poplar, though that tree oc- curs plentifully on the Ottawa, would not be so pre- dominant. But such an assemblage of drift-plants might be furnished by any American stream flowing in the lati- tude of 50° to 55° north. If a stream flowing to the north, it might deposit these plants in still more northern latitudes, as the McKenzie River does now. If flowing to the south, it might deposit them to the south of 50°. In the case of the Ottawa, the plants could not have been derived from a more southern locality, nor probably from one very far to the north. We may therefore safely as- sume that the refrigeration indicated by these plants would place the region bordering the Ottawa in nearly the same position with that of the south coast of Labrador fronting on the Gulf of St. Lawrence at present. The absence of all the more arctic species occurring in Lab- rador should perhaps induce us to infer a somewhat milder climate than this. The moderate amount of refrigeration thus required would in my opinion accord very well with the probable conditions of climate deducible from the circumstances in which the fossil plants in question occur. At the time when they were deposited the sea flowed up the Ottawa valley to a height of 200 to 400 feet above its present level, and the valley of the St. Lawrence was a wide arm of the sea, open to the arctic current. Under these con- ditions the immense quantities of drift-ice from the northward, and the removal of the great heating surface now presented by the low lands of Canada and New Eng- land, must have given for the Ottawa coast of that period a summer temperature very similar to that at present ex- perienced on the Labrador coast, and with this conclusion the marine remains of the Leda clay, as well as the few 232 THE GEOLOGICAL HISTORY OF PLANTi lij ( I land molluscs whose shells have been found in the beds containing the plants, and which are species still occur- ring in Canada, perfectly coincide. The climate of that portion of Canada above water at the time when these plants were imbedded may safely be assumed to have been colder in summer than at present, to an extent equal to about 5° of latitude, and this re- frigeiation may be assumed to correspond with the re- quirements of the actual geographical changes implied. In other words, if Canada was submerged until the Ottawa valley was converted into an estuary inhabited by species of Leda, and frequented by capelin, the diminu- tion of the summer heat consequent on such depression would be precisely suitable to the plants occurring in these deposits, without assuming any other cause of change of climate. I have arranged elsewhere the Post-pliocene deposits of the central part of Canada, as consisting of, in ascend- ing order : (1) The boulder clay ; (2) a deep-water de- posit, the Leda clay ; and (3) a shallow-water deposit, the Saxicava sand. But, although I have placed the boulder clay in the lowes. position, it must be observed that I do not regard this as a continuous layer of equal age in all places. On the contrary, though locally, as at Montreal, under the Leda clay, it is in other places and at other levels contemporaneous with or newer than that deposit, which itself also locally contains boulders. At Green's Creek the plant-bearing nodules occur in the lower part of the Leda clay, which contains a few boulders, and is apparently in places overlaid by large boulders, while no distinct boulder clav underlies it. The circumstances which accumulated the thick bed of boulder clay near Montreal were probably absent in the Ottawa valley. In any case we must regard the deposits of Green's Creek as coeval with the Leda clay of Montreal, and with the period of the greatest abundance of Leda THE TERTIARY TO THE MODERN PERIOD. 233 glacialis, the most exclusively arctic shell of these de- posits. In other words, I regard the plants above men- tioned as probably belonging to the period of greatest re- frigeration of which we have any evidence, of course not including that mythical period of universal incasement in ice, of which, as I have elsewhere endeavoured to show, in so far as Canada is concerned, there is no evidence whatever.* The facts above stated in reference to Post-pliocene plants concur, with all the other evidence I have been able to obtain, in the conclusion that the refrigeration of Canada in the Post-pliocene period consisted of a diminu- tion of the summer heat, and was of no greater amount than that fairly attributable to the great depression of the land and the different distribution of the ice-bearing arctic current. In connection with the plants above noticed, it is in- teresting to observe that at Green's Creek, at Pakenham Mills, at Montreal, and at Clarenceville on Lake Cham- plain, species of Canadian Puhnonata have been found in deposits of the same age with those containing the plants. The species which have been noticed belong to the genera Lymnea and Planorhis. The Glacial age was, fortunately, not of very long du- ration, though its length has been much exaggerated by certain schools of geologists, f It passed away, and a re- turning cosmic spring gladdened the earth, and was ush- ered in by a time of great rainfall and consequent denu- dation and deposit, which has been styled the '* Pluvial Period." The remains of the Pliocene forests then re- turned— with somewhat diminished numbers of species — * Notes on Post-Pliocene of Canada, " Canadian Naturalist," 1872. f This I have long maintained on grounds connected with Pleistocene fossils, amount of denudation and deposit, &c., and I am glad to see that Prestwich, the best English authority on such subjects, has recently an- nounced similar conclusions, based on independent reasons. 231 THE GEOLOGICAL HISTORY OF PLANTS. from the south and again occupied the land, though they have not been able, in their decimated condition, to re- store the exuberance of the flora of the earlier Tertiary. In point of fact, as we shall see in the next chapter, it is the floras originating within the polar circle and coming down from the north that are rich and copious. Those that, after periods of cold or submergence, return from the south, are comparatively poor. Hence the modern flora is far inferior to that of the Middle Kainozoic. In America, however, and in eastern Asia, for reasons al- ready stated, the return was more abundant than in Europe. Simultaneously with the return of the old temperate flora, the arctic plants that had overspread the land re- treated to mountain-tops, now bared of ice and snow, and back to the polar lands whence they came ; and so it hap- pens that, on the White Mountains, the Alps, and the Himalayas, we have insular patches of the same groups of plants that exist around the pole. These changes need not have required a very long time, for the multiplication and migration of plants are very rapid, especially when aided by the agency of migra- tory animals. Many parts of the land must, indeed, have been stocked with plants from various sources, and by agencies — as that of the sea — which might at first sight seem adverse to their distribution. The British Islands, for example, have no indigenous plants. Their flora consists mainly of Germanic plants, which must have migrated to Britain in that very late period of the Post- glacial when the space now occupied by the North Sea was mostly dry land. Other portions of it are Scandi- navian plants, perhaps survivors of the Glacial age, or carried by migratory birds ; and still another element consists of Spanish plants, brought north by spring mi- grants, and establishing themselves in warm and sheltered spots, just as the arctic plants do on the bleak hill-tops. THE TERTIARY TO THE MODERN PERIOD. 235 The Bermudas, altogether recent islands, have one hun- dred and fifty species of native plants, all of which are West Indian and American, and must have been intro- duced by the sea-currents or by migratory birds. And so the earth became fitted for the residence of modern man. Yet it is not so good or Edenic a world as it once was, or as it may yet become, were another revo- lution to restore a mild climate to the arctic regions, and to send down a new swarm of migratory species to renew the face of the earth and restore it to its pristine fertility of vegetable life. Thus closes this long history of the succession of plants, reaching from the far back Laurentian to the pret.'^nt day. It has, no doubt, many breaks, and much remains to be discovered. Yet it may lead us to some positive conclusions regarding the laws of the introduction of plants. One of these, and perhaps the most remarkable of all, is that certain prmciples were settled very far back, and have remained ever since. We have seen that in the earliest geological periods all that pertains to the struct- ure, powers, and laws of the vegetable cell was already fixed and settled. When we consider how much this implies of mechanical structure and chemical and vital property, the profound significance of this statement be- comes apparent. The relations in these respects between the living cell and the soil, the atmosphere and the sun- shine, were apparently as perfect in the early Palaeozoic as in any subsequent time. The same may be said of the structures of the leaf and of the stem. In such old forms as Nematophyton these were, it is true, peculiar and rudi- mentary, but in the Devonian and Carboniferous the structure of leaves and stems embodied all the parts and principles that we find at present. In regard to fructifi- cation there has been more progress, for, so far as we know, the highest and most complex forms of flowery. f 236 THE GEOLOGICAL HISTORY OF PLANTS. fruits, and seeds belong to the more recent periods, and simpler forms were at least dominant in the older times. Yet even in this respect the great leading laws and struct- ures of bisexual reproduction were perfected in the early Pala)ozoic, and the improvements introduced in the gym- nosperm and the angiosperm of later periods have con- sisted mainly in additions of accessory parts, and in modi- fications and refinements suited to the wants of the higher and more complex types. I 'r CHAPTER VIII. GENERAL LAWS OF ORIGIN AND MIGRATIONS OF PLANTS. — RELATIONS OF RECENT AND FOSSIL FLORAS. The origination of the successive floras which have occupied the northern hemisphere in geological time, not, as one might at first sight suppose, in the sunny climes of the south, but under the arctic skies, is a fact long known or suspected. It is proved by the occurrence of fossil plants in Greenland, in Spitzbergen, and in Grin- nell Land, under circumstances which show that these were their primal homes. The fact bristles with physical difficulties, yet is fertile of the most interesting theoreti- cal deductions, to reach which we may well be content to wade through some intricate questions. Though not at all a new fact, its full significance seems only recently to have dawned on the minds of geologists, and within the last few years it has produced a number of memoirs and addresses to learned societies, besides many less formal notices.* The earliest suggestion on the subject known to the ■writer is that of Prof. Asa Gray, in 1867, with reference to the probable northern source of the related floras of North America and eastern Asia. With the aid of the new facts disclosed by Heer and Lesquereux, Gray re- * Saporta, "Ancienne Vegetation Polaire"; Hooker, "Presidential Address to Royal Society," 1818; Thistleton Dyer, "Lecture on Plant Distribution"; Mr. Starkie Gardner, "Letters in 'Nature,'" 1878, &c. The basis of most of these brochures is to be found in Heer's " Flora Fossilis Arctica." 22 238 THE GEOLOGICAL HISTORY OF PLANTS. i riginated, there might be an intermixture of the two floras. But such a mixed group should in that latitude be referred to a lower horizon than if found in temperate regions. Dr. Nathorst, as already stated, has recently obtained new facts which go to show that plants of two distinct hori- zons may have been intermixed in the collections sub- mitted to Heer. * "Transactions of the Swedish Academy," 1871 ; "Journal of the London Geological Society," vol. xxviii. 242 TDE GEOLOGICAL HISTORY OF PLANTS. rsif >' ! Between 1870 and 1873 my attention was turned to the two subfloras intermediate between those of tiie Devo- nian and the coal-formation, the floras of the Lower Carboniferous (Subcarboniferous of some American geol- ogists) and the Millstone Grit, and in a report upon these* similar deductions were expressed. It was stated that in Newfoundland the coal-beds seem to belong to tlic Millstone Grit series, and as we proceed southward they belong to progressively newer portions of the Car- boniferous system. The same fact is observed in the coal-beds of Scotland, as compared with those of Eng- land, and it indicates that the coal-formation flora, like that of the Devonian, spread itself from the north, and this accords with the somewhat extensive occurrence of Lower Carboniferous rocks and fossils in the Parry Islands and elsewhere in the arctic regions. Passing over the comparatively poor flora of the earlier Mesozoic, consisting largely of cycads, pines, and ferns, and as yet little known in the arctic, and which may have originated in the south, though represented, accord- ing lu Ilccr, by the supposed Jurassic flora of Siberia, we find, especially at Kome and Atane in Greenland, an in- teresting occurrence of those earliest precursors of the truly modern forms of plants which appear in the Creta- ceous, the period of the English chalk and of the New Jersey greensands. There are two plant-groups of this age in Greenland ; one, that of Kome, consists almost en- tirely of ferns, cycads, and pines, and is of decidedly Mesozoic aspect. This is called Lower Cretaceous. The other, that of Atane, holds remains of many modern tem- perate genera, as Popvlus, Mi/n'ra, Ficus, Sassafras, and Magnolia. This is regarded as Upper Cretaceous. Rest- ing upon these Upper Cretaceous beds, without the inter- * "Fossil Plants of Lower Carboniferous and ^lillstone Grit Forma- tions of Canada, ' pp. 47, ten plates, Montreal, 1S73. i: ! "\\\\ GENERAL LAWS OF ORIGIN AND MIGRATION. 243 vention of any other formation,* are beds rich in plants of much more modern appearance, and referred by Ileer to the Miocene period, a reference, as we have seen, not Wf.rranted by comparison with the Tertiary plants of Eu- rope or of America. Still farther north this so-called Miocene assemblage of plants appears in Spitzbergen and Grinnell Land ; but there, owing to the predominance of trees allied to the spruces, it has a decidedly more boreal character than in Greenland, as might be anticipated from its nearer approach to the pole.f If now we turn to the Cretaceous and Tertiary floras of western America, as described by Lesquereux, New- berry, and others, we find in the lowest Cretaceous rocks there known — those of the Dakota group — which may be in the lower part of the Middle Cretaceous, a series of plants J essentially similar to those of the so-called Upper Cretaceous of Greenland. They occur in beds indicating land and fresh-water conditions as prevalent at the time over great areas of the interior of America. But over- lying this plant-bearing formation we have an oceanic limestone (the Niobrara), corresponding in many respects to the European chalk, and extending far north into the British territory,* indicating that the land of the Lower Cretaceous was replaced by a vast Mediterranean Sea, filled with warm water from the equatorial currents, and not invaded by cold waters from the north. This is suc- ceeded by thick Upper Cretaceous deposits of clay and sandstone, with marine remains, though very sparsely * Nordenskiold, " Expedition to Greenland," " Geological Magazine," 1872. f Yet even here the bald cypress {Taxodium dis/lchum), or a tree nearly allied to it, is found, though this species is now limited to the Southern States. Ficldcu and De Ranee, " Journal of the Geological So- ciety," 1878. 1(. Lesquereux, " Report on Cretaccoiis Flora." ** G. M. Dawson, " Report on Forty-ninth Parallel" 244 THE GEOLOGICAL HISTORY OF PLANTS. ml distributed ; and these show that further subsidence or denudation in the north had opened a way for the arctic currents, killing out the warm-water animals of the Nio- brara group, and filling up the Mediterranean of that period. Of the flori* of these Upper Cretaceous periods, which must have been very long, we know something in the interior regions, from the discovery of a somewhat , rich flora in the Dunvegan beds of the Peace River dis- trict, on the northern shore of the great Cretaceous Medi- terranean;* and on the coast of British Columbia we have the remarkable Cretaceous coal-field of Vancouver Island, which holds the remains of plants of modern genera, and, indeed, of almost as modern aspect as those of the so-called Miocene of Greenland. They indicate, however, a warmer climate as then prevalent on the Pa- cific coast, and in this respect correspond with a peculiar transition flora, intermediate between the Cretaceous and Eocene or earliest Tertiary of the interior regions, and which is described by Lesquereux as the Lower Lig- nitic. Immediately above these Upper Cretaceous beds we have the great Lignite Tertiary of the West — the Laramie group of recent American reports — abounding in fossil plants, at one time regarded as Miocene, but now known to be Lower Eocene, though farther south extending up- ward toward the Miocene age.f These beds, with their characteristic plants, have been traced into the British territory north of the forty-ninth parallel, and it has been shown that their fossils are identical with those of the * " Reports of Dr. G. M. Dawson, Geological Survey of Canada." Also, " Transactions of the Royal Society of Canada," vol. i. f Lesquereux's " Tertiary Flora " ; " White on tlic Lar