5^4 



NATURE 



[Sept. 20, 1883 



the organic material has been dissipitated, and what little remains 

 has often been consolidated in such a way that it is merely 

 moulded upon the sculptured inorganic substance which it 

 covers, and hence affords no information respecting the exterior 

 of the fossil when a living organism. It is, in my opinion, from 

 specimens like these that the smooth bark of the Catamite has 

 been credited with a fluted surface, and the Trigonocarpons with 

 a merely triangular exterior and a misleading name, as it long 

 caused the inorganic casts known as Sternbergite to be deemed 

 a strange form of plant that had no representative amongst 

 living types. In other cases the outerimst surface of the bark 

 is brought into close contact with the surface of the vascular 

 cylinder. I hive a Stigmaria in which the bases of the rootlets 

 appear to be planted directly upon that cylinder, the whole of 

 the thick intermediate bark having disappeared. In other 

 examples that vascular zone has also gone. Thus the innermost 

 and outermost surfaces • fa cylinder, originally many inches apart, 

 are, through the disappearance of the intermediate structures, 

 brought into close approximation. In such cases, leaves and 

 other external appendages appear to spring directly from what is 

 merely an inorganic cast of the interior of the pith. I believe 

 that many of our Calamites are in this condition. Such examples 

 have suggested the erroneous idea that the characteristic longi- 

 tudinal llutings belong to the exterior of the bark. 



Fungi. — Entering upon a more detailei review of our know- 

 ledge of the Carboniferous plants, and commencing at the bottom 

 of the scale, we cine to the lowly group of the Fungi, which 

 are unquestionably represented by the Peronosporiies antiquai ins ' 

 of Worthington Smith. There seems little reason for doubting 

 that this is one of the Phycomycetous Fungi, possibly somewhat 

 allied to the Saprolegniea ; but since we have as yet no evidence 

 respecting its fructification, these closer relationships must, for 

 the present, remain undetermined. So far as I know, this is the 

 only Fungus satisfactorily proved to exist in the Carboniferous 

 rocks, unless the Excipulites Neesii of Goeppet t and one or two 

 allied forms belong to the Fungoid group. The PolyporiUs 

 Bowmanni is unquestionably a scale of a Holoptychian fish. 



Alga. — Numerous objects supposed to belong to this family 

 have been di-covered in much older rocks than Carboniferous 

 ones. The subject is a thorny one. That marine plants of some 

 kind must have existed simultaneously with the molluscous and 

 other plant-eating animals of Palaeozoic times is obviously indis- 

 putable. But what those plants were is another question. The 

 widest differences of opinion exist in reference to many of them. 

 A considerable number of those recog dsed by Schimper, Saporta, 

 and other paheo botanists, are declared by Nathorst to be merely 

 inorganic tracks of marine animals — and in the case of many of 

 these I have little doubt that the Swedish geologist is right. 

 Others have been shown to be imperfectly preserved fragments 

 of plants of much higher organisation than Algae, branches of 

 Conifers even being included amongst them. I have as yet seen 

 n me of Carboniferous age that could be indisputably identified 

 with the family of Algae, though there are many that look like, 

 and may probably be, such. The microscope alone can settle 

 this question, though even this instrument fails to secure unity of 

 opinion in the case of Dawson's Protota tites, and no other of the 

 supposed seaweeds hitherto discovered have been sufficiently well 

 preserved to bear the microscopic test ; hence I think that their 

 existence in Carboniferous rocks can only be regarded as an 

 improve 1 probability. Mere superficial resemblances do not 

 satisfy the severe demands of modem science, and probabilities 

 are an insufficient foundation upon which to build evolutionary 

 theories. 



Seeing what extremely delicate cell-structures are preserved in 

 the Carboniferous beds, it cannot appear other than strange that 

 the few imperfect Fungoid relics just referred to constitute the 

 only terrestrial cellular Cryptogams that have been discovered in 

 the Carboniferous strata. The Darwinian doctrine would sug^e t 

 that these lower forms of plant life ought to have ab lunded in 

 that primaeval age ; and that they were capable of being preserved 

 is proved by the numerous specimens met with in Tertiary 

 dep isits. Why we dj not find such in the Palaeozoic beds is stiil 

 an unsolved problem. 



Vascular Cryptogam*. — The Vascular Cryptogams, next to be 

 considered, burst upon us almost suddenly and in rich profusion 

 during the Devonian age; they are equally silent in the Devonian 

 and Carboniferous; strata a:- to their ancestral descent. 



Ferns. — The older taxonomic literature of Palaejzoic F^rn life 

 is, with few exceptions, of little scientific value. Hooker and 

 others have uttered in vain wise protests against the system that 

 " Memoir " xi. p. 299. 



has been pursued. Small fragments have had generic and 

 specific names as-igned to them, with supreme indifference to 

 the study of morphological variability amongst living types. The 

 undifferentiated tip of a terminal pinnule has had its special 

 name, whilst the more developed structures forming the lower 

 part of a frond have supplied two or three more species. Then 

 the distinct forms of the fertile fronds may have furnished 

 additional ones, whilsr a further cause of confusion is seen in the 

 wide difference existing between a young half-developed seedling 

 and the same plant at an advanced stage of its growth. Any one 

 who has watched the development of a young Polypodium 

 aureum can appreciate this difference. Yet, in the early stages 

 of paleeontological research, observers c mid scarcely have acted 

 otherwise than as they did in assigning na nes t j these fragments 

 — if only for temporary working purposes, Our error lies in 

 misunderstanding the true value of such names. At present the 

 study of fossil ferns is affording some promise of a newer and 

 healthier condition. We are slowly learning a little about the 

 fructification of sjme species, and the internal organisation of 

 others. Facts of these kinds, cautiously interpreted, are surer 

 guides than mere external contours ; unfortunately, such facts 

 are, as yet, but few in number, and when we have them we are 

 too often unable to i ienti f y our detached sporangia, stems, and 

 petioles with the fronds of the plan's to which they primarily 

 belonged. 



That all the Carboniferous plants included in the genera 

 Pecopttris, Nturopteris, and Sphenopteris are ferns appears to be 

 most probable; but what the true affinities of the objects in- 

 cluded in these ill-defined genera may be is very doubtful. Here 

 and there we obtain glimpses of a more definite kind. That the 

 Devonian Pahnapteris Hibernica is a Hymenophyllous form 

 appears to be almost certain ; and on corresponding grounds we 

 may conclude that the Carboniferous forms Sphenopteris tricho- 

 ma 11 oiJcs, S. Humboltii, 1 and Hymenophyllum Wcissii, 1 belong 

 to the siine group. The fructification of the two latter leaves 

 little rojm for doubting their position, whil t the foliage of some 

 other species of Sphenopterisis suggestive of similar conclusions, 

 but until their fructification is discovered this cannot be deter- 

 mined. An elegant form of Sphenopteris (S. tenella, Brong., 

 .S. lanceolata of Gutbier), recently described by Mr. Kidson of 

 Stirling, abundantly justifies caution in dealing with these 

 Sphenopterides. This plant possesses a true Spheuopteroi 1 

 foliage, but its fructification is that of a Marattiaceous Danaid. 

 The sporangia are elongated vertically, and have the round 

 terminal aperture of both the recent and fossil Danaia — a group 

 of plants far removed from the Hymenophyllaceous type of 

 Sphenopterid already referred to. 



Whether or not this Sphenopteris was really Marattiaceous in 

 other features than its fructification is uncertain; but I think 

 that we have indisputably got stems and petioles of Marattiaceae 

 from the Carboniferous strata. My friend M. Renault and I, 

 without being aware of the fact, simultaneously studied the 

 Medullosa clcgans of Colta. This plant was long regarded as 

 the stem of a true Monocotyledon, a decision the accuracy of 

 which was doubted first by Brongniart and afterwards by Binney. 

 M. Renault's memoir and my part vii. appeared almost simul- 

 taneously. We then found that we had alike determined the 

 supposed Monocotyledon to be not only a fern, but to belong t > 

 the p culiarly aberrant group of the Marattiacece. As yet we 

 know nothing of it- f diage and fructification. 



M Grand- Eury has figured 3 a remarkable series of ferns from 

 the coal-measures of the basin of the Loire, the sporangia of 

 which exhibit marked resemblances to those of the Maxattiacese. 

 This is especially the case with his specimens of Asterotheca and 

 Scolecopteris, A as also with his Peeepteris MaratlialAeca, P. An- 

 giotheca, and P. Danaertheca, but there is some doubt as to the 

 dehiscence of the sp trangia of these plants ; hence their Marat- 

 is character is not absolutely established. 



That the c lal-measures contain the remains of arborescent 

 ferns his long been known, especially from their abundance at 

 Autun. In Lancashire I have only met with the stems or petioles 

 of one species preserving their internal organisation. 1 The Rev. 

 H. II. Iliggms obtained stems that appear to have been tree- 

 ferns from Ravenhead, in Lancashire, and it is probable that 



1 "Schimper," vol. i. p. 408. ' Ib'ui. p. 415. 



3 '" Fl >re Carbon'fere du Department de la Loire et du Centre de la 

 France." 



4 Loc. cii. Tab. viii. Figs 1-5, 



5 Psaronitts Rrnaultii, Mem >ir vii. p. 10, and Memoir xii. PI. iv. Figs. 16. 

 These and other similar references are 10 my scries of Mem iirs " On the 

 Organisation of the Fo-sil Plants of the Coal-measures," published in the 

 " Philosophical Transactions " 



