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Maps, plates, charts, etc., may be filmed at different reduction ratios. Those too large to be entirely included in one exposure are filmed beginning in the upper left hand corner, left to right and top to bottom, as many frames as required. The following diagrams illustrate the method: Les cartes, planches, tableaux, etc., peuvent dtre filmds d des taux de reduction diffdrents. Lorsque le document est trop grand pour dtre reproduit en un seul clichd, il est filmd d partir de Tangle supdrieur gauche, de gauche d droite. et de haut en bas, en prenant le nombre d'images ndcessaire. Les diagrammes suivants iilustrent la mdthode. 1 2 3 1 2 3 4 5 6 f 55 '-1 :j^ Vk * .'». 1 55^ .f ,.j** Q ^ SWferpC mm February, 1878. (From the Canadian Naturalist, Vol. VIII. No. y.) NOTES 'A >'. H, S. / ON 80MK A ^v? i % \y / Scottis'h Devonian Plants. By J. W. Dawson, LL.D., F.R.S., Principal and Vici-Chancellor of McGill University, Montreal. (Read before the EdinburKh Geological Society, 20th Deo. 1877, D. Milne Home. Esq., LL.D.. President, in the chair.) « Since the publication of my Memoirs on Devonian Plants, in the Journal of the Geological Society of London and in the Reports of the Canadian Geological Survey, I have watched with some interest the progress of discovery in the Devonian Flora of Scotland, and desire now to make a few remarks on new and critical forms, and on opinions which have been expressed by workers in this field. Previously to the appearance of my descriptions of Devonian plants from North America, Hug'i Miller had described forms from the Devonian of Scotland, similar to those for which I proposed the generic name Psilophyton ; and I referred to these in this connection in my earliest description of that genus.* He had also recognized what seemed to be plants allied to Lycopods and Conifers. Mr. Peach and Mr. Duncan had made additional discoveries of this kind, and Sir J. Hook«r and Mr. Salter had described some of these remains. More recently Messrs. Peach, Carruthers and McNab have worked in this iSeld, and in the present year f Messrs. Jack and Etheridge have summed up the facts and haye 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 charac- teristic 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 from the Devonian, but * Journal Geological Society, London, 18S9. •flbid, 1877. - .■•7-'i ./ te''^ N6 these had been well figured and described by Salter, and had been identified with L. notliam of Unger, a species evidently distinct from mine, as was also that figured and described by Salter, whether identical or not with Unger's species. In 1870 I had for the first time an opportunity to study Scottish speci- mens in the collection of Mr. Peach ; and on the evidence thus afforded I stated confidently that these specimens represented a species distinct from L. Gnnpiannm, perhaps even generically so.* It diff"ers from L. Gaaputimm in its habit of growth by developing small lateral brunches instead of bifurcating, and in its foliage by the absence or obsolete character of the leaf- bases and the closely placed and somewhat appressea leaves. If an appearance of Hwelling at the end of a lateral brr.nch 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. Gaspianam. The Lepidodendron from the Devonian of Belgium described and figured by Crepin,f has a better claim to such identification, and would soem to prove that this spi!cies 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. Guspin num.1 In the earliest description of Psilophjjtoa I recognized its probable generic affinity with Miller's ' dichotomous plants,' with Salter's 'rootlets,' and with Goeppert's Ilaliserites Dechenumns, and stated that I had " little doubt that materials exist in the Old Rod Sandstone 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 fucoids, and Goeppert's Haliscrltes was a name applicable only to fucoids, and since the structure and fruit of my plants placed them near to Lycopods, I was under the necessity of giving them a special generic name, nor could I with certainty affirm their specific identity with any European species. The comparison of the Scottish specimens with woody "ootlets, though incorrect, is in one respect creditable to the acumen of Salter, as in almost any state of preservation an experienced eye can readily perceive that branchlets of * Report on Devonian Plants of Canada, 1871 . t Observations sur qnclques Plaiites Fossiles cles depots Devonieus. t Proceedings Ueological Society of London, March 1871. >^/ */3ro f 8 PsUophyton must have been woody rather than herbaceous, and their appearance is quite difiFerent from that of any true Algae. The type of PsUophyton is my P. princepn, of which the whole of the parts and structures are well known, the entire plant being furnished in abundance and in situ in the rich plant-beds of Gaspe. A second species, P. rohuafins, has also afforded well characterized fructification. P. elfgaus, whose fruit appears as "oval scales," no doubt bore sac-like spore-cases resembling those of the other species, but in a different position, and perfectly flattened in the specimens procured. The only other Canadian species, P. ghthnim, being somewhat different in appearance from the others, and not having aflForded any fructi- fication, must be regarded as uncertain. The generic characters of the three first species may be stated as follows : — Stems dicliotomous, with rudimentary subulate leaves, some- times obsolete in terminal branchlets and fertile branches ; and in decorticated specimens represented only by punctiform scars. Young branches circinate. Rhizomata cylindrical, with circular root-areoles. Internal structure of stem, an axis of scalariform vessels enclo.sed in a sheath of imperfect woody tissue and covered with a cellular biirk more dense externally. Fruit, naked sac- like spore-cases, in pairs or clusters, terminal or lateral. The Scottish specimens conform to these characters in so far as they are known, but not having as yet afforded fruit or inter- nal structure, they cannot be specifically determined with cer- tainty. More complete specimens should be carefully searched for, and will no doubt be found. In Belgium, M. Crepin has described a new species from the Upper Devonian of Condroz under the name P. Condriislannm, [1875]. It wants however some of the more important charac- ters of the genus, and differs in having a pinnate ramification giving it the aspect of a fern. In a later paper [1876] the author considers this species distinct from PsUophyton, and proposes for it a new generic name Rhacophyton. In a note he states that Mr. Carruthers informs him that he regards PsUo- phyton as founded on the axes of Lepidodendra and on the fruit of ferns of the genus Rhodea of Stur. For this statement I have no published authority on the part of the English botanist, and it is certainly quite destitute of fd Jation in nature. My original specimens of PsUophyton are low plants with slender stems growing from rhizomata^ and their leaves and fruits are 1^1 attuched to them, while Rhodea is merely a provisional genus formed to include certain ferns of the Hymonophyllid group, but otherwise of uncertain affinities. In the same not« M. Crepin intimates that Mr. Carruthers has abandoned his Pnilophyton Dcchenianum, published in the Journal of Botany for 1843, and in which he had included Salter's Lepidodendron nothum and fji/ropoditcH Milleri and " rootlets," as well as Goeppert's Ilali- sirites Dechenidiius and a peculiar plant given to him by Sir P. Egerton ! -^ Such a change of opinion I must admit to be judi- cious. The fact that these plants could, even conjecturally, be identified by a skilful botanist, shows however how imperfectly they are known, and warrants some investigation of the causes of this obscurity, and of the true nature of the plants. The characters given by Mr. Carruthers in his paper of 1873 for the species /'. Declienianuni, are very few and general: — " Lower branches short and frc(juently branching, giving the plant an oblong circumscription." Yet even these characters do not apply, so far as known, to Miller's fucoids or Salter's rootlets or Goeppert's ILdiseritex. They merely express the peculiar mode of branching already referred to in Salter's Lepidodendron nothum. The identification of the former plants with the Lepi- dodendron and Lycopodites indeed rests only on mere juxtapo- sition of fragments, and on the slight resemblance of the decorti- cated ends of the I ;'anche^ of the latter plants to Psilophy ton. It is contradicted by the obtuse ends of the branches of the Lepidodendron and Lyco2)odifes, and by the apparently strobi- laceous termination of some of them. Salter's description of his Lepidodendron is quite definite, and accords with specimens placed in my hands by Mr. Peach : — " Stems half an inch broad, t ipering little, branches short ; set on at un acute angle, blunt at their terminations. Leaves in seven to ten rows, very short, not a line long and rather spread- ing than closely imbricate." These characters however, in so * Mr. (y'arrutheris has elsowhovo 'n\\iniifntd Lepidodendron not hum and L. Guispianum with Leptoi>hlcuiii rhombicum, and this with an Austral- ian species ooUectod by Mr. Daintreo in Queensland, but which I subsequently found to be a sp(!cies allied to the well known Lepido- dendron tetrciffoniim ot the Lower Carboniferous, and which had been previously discovered by Mr. Solwyn in the Carboniferous of Victoria. See Carruthers' paper in the Journal of the Geological Society, vol. 28, and my criticism in vol. 29, wh>''h last was however only printed in abstract, and with some comments under the head of" Discussion," to which if present I could have very easily replied. TT i 11 ^^ / 1 far as they <»o, arc rather those of the fjfenns Li/copfxh'trs tlmn of Lepi(fo(leiidro)i, from which this plant differs in wanting; any distinct leaf-bases, and in its short crowded loaves. Tt is to be obseA'od that they apply also to Salter's LijcopoiUtvn Ml/hri, and that the difference of the foliage of that species may be a result merely of different state of preservation. For those reasons I am disposed to place these two supposed species toirother, and to retain for the species the name Li/rojxHlitcs Millcri. Tt may be chaiiicterizod by the description above i^ivoii. with merely the modification that the leaves are son)etimos one-third of an inch lonj; and secund. Decorticated branches of the above species may no doubt be mistaken for I*siloj)hi/fo)i, but are nevertheless (juite distinct from it, and the slender branching dlchotomous stems, with terminations v'hich, as Miller graphically states, are "like the tendrils of a pea," are too characteristic to be easily mistaken, even when neither fruit nor leaves appear. With reference to fructification, the form of L. Mif/eri. renders it certain that it must have borne strobiles at the ends of its branchlets, or some substitute for these, and not naked spore-cases like those of Psilophyton. The remarkable fra<;ment communicated by Sir Philip E<:;erton to Mr. Carruthers,-'^ belongs to a third j^roup, and has I think been quite misunderstood. I am enabled to make this statement with some confidence, from the fact that the reverse or counter- part of Sir Philip's specimen was in the collection of Sir Wyville Thomson, and was placed by him in my hands in 187(J. Ttwas noticed by me iji a paper on New Devonian Plants, in the Journal of the Geologiciil Society of London in 1871, in the following terms : — "In his recently published ' Paldontologie,' Schimper (evi- dently from inattention to the descriptions and want of access to specimens) doubts the Lycopodiaceous character of species of Lycopodites described in my papers in the Journal of this Society from the Devonian of America. Of these L. Rlchardsoni and L. Matthcwi are undoubtedly very near to the modern genus Lycopodium. L. Vanuxcmii is, I admit, more problematical ; but Schimper could scarcely have supposed it to be a fern or a fucoid allied to Caiderpa had he noticed that both in my species and the allied L. pennce/ormis of Goeppert, which he does not •Journal of Botany, 1873. 6 X appear to notice, the pinnules are articulated upon the Htem, and leave scars where they have fallen oflF. When in Belfjist last summer I was much interested by finding in Prof. Thomson's collection ;i specimen from Caithness, which shows a plant appa- rently of this kind, with the same long narrow pinnae or leaflets, attached, however, to thicker stems, and rolled up in a circinate manner. It seems to be a plant in vernation, and the parts are too much crowdi'd and pressed to<;ether to admit of being accu- rately figured or described ; but I think 1 can scarcely be deceived as to its true niture. The circinate arrangement in this case would favour a relationship to ferns ; but some Lycopodiaceous plants also roll themselvea in this way, and so do the branches of the plants of the genus PsUophijtun.'' No figure of the plant was given, and Mr. Carruthers, if he noticed the reierenec, very probably did not connect it with the plant wliieh he received i'rom Sir Philip Egerton. His figure however, published in tiie Journal of Botany for 187IJ, leaves no room to doubt that he has had in his possession the counterpart of Thomson's specimen, of which a figure is given in this paper. My interpretation of it diifers considerably from his, and as the matter is of some palaeontological interest, I shall proceed to describe the specimen from njy point of view. The speeiiuen consists of a short erect stem, on which are placed somewhat stout alternate branches, extending obliquely outward and then curving inward in a circinate manner. The lower ones 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 placed in a crowded manner, and which are the " tufts of linear bodies " referred to by Mr. Carruthers. The specimen is thus not a spike of fruc- tification but a young stem or branch in vernation, and which when unrolled would be of the form of those peculiar pinnate LycopoiUU'H of which L. Vannxemii of the American Devonian and L. pennirfonnis of the European Lower Carboniferous 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 the detached branch of Lycopodites Milleri which lies at right angles to it on the same slab (see figure). As to the afl&nities of the singular type of plants to which this specimen belongs, I may quote from my Report on n %. \ ~\i •r ^ n t> > ••% the Lower Carboniferous plantt' of CuDuda, in which I have described an allied species, L. plumuln : — '* The botanical relations of these plants must reniain subject to doubt, until either their internal structure or their fructifica- tion can be discovered. In the mean time I follow Goeppert in placing them in what we must re;^ard as the provisional «;enus Li/('()jH)^incnt of coarsc-i^rained wood. Od microscopic examination of it, however, I concluded that it had been a bundle of spicules of u sponj^e of the type of Ifyalo- nema. This I still believe to be its true nature. In studying; the plants of the older rocks, the botanist requires to be on his guard as to the Ah^vc ami Zoophytes of these forma- tions which simulate land plants. In the latter group I know no forms mora deceptive than those of Hall's genus Inoai.ulis, which is regarded as a relative of tlie Graptolites. A specimen now before me, from the collection of Col. Grant, of Hamilton, Ontario, in its ramification and appearance of foliage, bears the closest resemblance to a lycnpodiaceous plant, and I have seen what appears to be the base of a Dicti/oihinn from the Niagara formation, which might rtadily be mistaken for a small and peculiar species of Pxilophijton. Messrs. Jack and VitheriJge have given an excellent summary of our present knowledge of the Devonian Flora of Scotland, in the Journal of the London Geological Society. From this it would appear that species referable to the genera Culamites, Lepidodendron , Lj/copodite.s, Psilophi/ton, Arthrostigma, Archa;- opterigj Cfiulopterix, Pdo.opifi/s, Aruiicarloxijlon, and Stlgma- ria have been recognized. The plants described by those gentlemou from the Old Red Sandstone of Callender, I should suppose, from their figures and descriptions, to belong to the genus Arthroxtigma, rather than to Fsilophi/ton. I do not attach any importance to the sugges- tions referred to by them, that the apparent leaves may be leaf- bases. Long leaf-bases, like those characteristic of Lepidojloyos, do not occur in these humbler plants of the Devonian. The stems with delicate '' horizontal processes " to whicii they refer may belong to Ptilophijtou or to PintmlHrid. In conclusion, I need scarcely say that I do not share in the doubts expressed by some British Palaeontologists as to the dis- tinctness of the Devonian and Carboniferous Floras. In Eastern • Since the ahovc was written, Lcsquorcnx has described supposed land plants from the Cincinnati Group (Lower Silurian) of Ohio. Saporta has discovered what he regards as a tern in rocks of similar age in France, and Claypole will shortly describe an apparently lepidodendroid tree (GlypwdenJron') from the Clinton Group of Ohio ; but neither of these is quite so old as the Skiddaw plants. i .if' 10 America, where these formations are mutually unconformable, there is, of course, less room for doubt than in Ireland and in Western America, where they are stratigraphically continuous. Still, in passing from the one to the other, the species are for the most part different, and new generic forms are met with, and, as I have elsewhere shown, the physical conditions of the two periods were essentially different.* It is, however, to b' bserved that since, as Stur and others have shown, C<(lumitc.s nidudns and other forms distinctively Devonian in Americ.i, occur in Europe in the Lower Carboni- ferous, it is not unlikely that the Devonian Flora, like that of the Tertiary, appeared earlier in America. It is also probable, as I have shown in the Reports already referred to, that it ap- peared earlier in the Arctic than in the Temperate zone. Hence an Arctic or American Flora, really Devonian, may readily be mistaken for Lower Carboniferous by a botan'st basing his cal- culations on the fossils of temperate Europe. Even in America itself, it would appear from recent discoveries in Virginia and Ohio, that certain Devonian forms lingered longer in those regions than further to the North-east ;f and it would not be surprising if similar plants occurred in later beds in Devonshire or in the South of Europe than in Scotland. Still, these facts, properly understood, do not invalidate the evidence of fossil plants as to geological age, though errors arising from the neglect of them are still current. I trust that Scottish workers in this interestinii; though diffi- cult branch of investigation, will be encouragod by the success they have already attained to still more diligent seaich. in col- lecting, the smallest and mo.st obscure fragments should not be neglected. Such specimens, when placed in due relation to others previously obtained, may reveal the most important truths ; or if by themselves unintelligible, may be rendered valuable by subsequent discoveries. The greatest care should be taken to rescue every portion of the specimens found, and to keep together those that belong to the same plant ; and every fragment likely to show microscopic structure should be carefully preserved. Painstaking work of this kind will be sure to be rewarded by important discoveries ; and I know by long experience that none other is likely to be successful, * Reports on Devonian Plants and Lower Carboniferous Plants of Canada. t Andrews, Pala3ontology of Ohio, Vol. II. Meek, Fossil Plants from Western Virginia, Philos (Society, Washington, IS?.*), ^ I I ., ' ■s^y , / 1 . PTlLOrUYTOX TlIOMSONI. (II) ImprL'ssiou of plant in vornutiou. (//) ijifuiciies conjecturally ivstorod. (r) J5ran('li(!s of Lj/copo'liie^ MiUeri. In tliis ( ut tlif parts of the fossil an; given morf coarsely and 'iistiiU'tlv than in the orijiina!.