Chapter 5

Fig. 31.—Erian fruits, &c., some gymnospermous, and probably ofCordaitesand Taxine trees (St. John, New Brunswick), A,Cardiocarpum cornutum. B,Cardiocarpum acutum. C,Cardiocarpum Crampii. D,Cardiocarpum Baileyi. E,Trigonocarpum racemosum. E1, E2, Fruits enlarged, F,Antholithes Devonicus. G, Annularia acuminata, H,Asterophyllites acicularis. H2, Fruit of the same, K,Cardiocarpum(? young ofA.), L,Pinnularia dispalans(probably a root).

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 asSyringoxylon mirabile.[BD]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 formationto 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 Middle Cretaceous suggests very grave doubt as to the authenticity of the specimen. I record the fact, waiting further discoveries to confirm it. Of the character of the specimen which I have described I entertain no doubt.

[BD]“Journal of the Geological Society,” vol. xviii.

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 wonderful expansion of the now modest groups of Rhizocarps and Lycopods, and that the flora as a whole belongs to the highest group of Cryptogams and the lowest of Phænogams, 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. Scudder. 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 grasshoppers (NeuropteraandOrthoptera), or intermediate between the two. It is probable that the larvæ 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 modernBarramunda orCeratodusof Australia, and with teeth suited for grinding vegetable food. It is also possible that some of the smaller plate-covered fishes (Placoganoids, likePterichthys) 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 Sporangites.

Itis, of course, very unsatisfactory to give names to mere fragments 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 meSporangites, under the supposition that they were Sporangia rather than spores, this name has so far been vindicated by the discovery of the spore-cases belonging to them, so that I think it may still be retained as a provisional name; but I would designate the whole asProtosalviniæ, 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 recognized as distinct forms:

1.Protosalvinia Huronensis, Dawson,Syn.,Sporangites Huronensis, “Report on Erian Flora of Canada,” 1871.—Macrospores, in the form of discs or globes, smooth and thick-walled, the walls penetrated by minute radiating pores. Diameter about one one-hundredth of an inch, or a little more, When in situ several macrospores are contained in a thin cellular sporocarp, 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, andin Ohio by Prof. Edward Orton, and at Chicago by Dr. H. A. Johnson and Mr. B. W. Thomas, also in New York by Prof. J. M. Clarke.

The macrospores collected by Mr. Thomas from the Chicago clays and shales conform closely to those of Kettle Point, and probably 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. ThomasS. Chicagoensis, and may be regarded as a varietal form. Specimens isolated from the shale and mounted dry, show what seems to have been the hilum or scar of attachment better than those in balsam.

Sections of the Kettle Point shale show, in addition to the macrospores, wider and thinner shreds of vegetable matter, which I am inclined to suppose to be remains of the sporocarps.

2.Protosalvinia(Sporangites)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 reniform sporocarps, each containing from four to twenty-four macrospores. Longest diameter of sporocarps three 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 below, 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 specimens of Protosalvinia occur. These beds are very widely distributed, and abound inProtosalviniaandSpirophyton.

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 specimens indicate that each prominence or tubercle contained several macrospores. At first sight it would be easy to mistake these bodies for valves ofBeyrichia.

Found in the same formations with the last species, though, in so far as the specimens indicate, not precisely in the same beds. Collected by Mr. Derby.

4.Protosalvinia Clarkei, Dawson,P. bilobata, Clarke, “American Journal of Science.”—Macrospores two-thirds to one millimetre indiameter. One, two, or three contained in each sporocarp, which is cellular. The macrospores have very thick walls with radiating tortuous tubes. Unless this structure is a result of mineral crystallisation, these macrospores must have had very thick walls and must have resembled 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 asPachytheca, though on a smaller scale.

It is to be observed that bodies similar to these occur in the Boghead 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. They occur in groups or patches, which seem to be enclosed in a smooth and thin membrane or sporocarp. It is quite likely that these bodies are generically distinct fromProtosalvinia.

5.Protosalvinia punctata, Newton, “Geological Magazine,” New Series, December 2d, vol. ii.—Mr. Newton has named the discs found in the white coal and Tasmanite,Tasmanites, the species beingTasmanites punctatus, but as my nameSporangiteshad 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 Huxley 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 showsSporangitesof the type of those in the Erian shales. Quekett, 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 Vanuxemiiof “Report on Devonian and Upper Silurian Plants,” Part I., page 35,L. plumulaof “Report on Lower Carboniferous Plants,” page 24, Plate I., Figs. 7, 8, 9.) In the reports above referred to, these remarkable pinnate, frond-like objects were referred to the genusLycopodites, as had been done by Goeppert in his description of the European speciesLycopodites pennæformis, 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 themPlumalina, and has regarded them as animalstructures, allied to hydroids, Lesquereux has described some of the Carboniferous forms under the generic nameTrochophyllum, which is, however, more appropriate to plants with verticillate 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”[BE]separated this group from the genusLycopodites, and formed for it the genusPtilophyton, in allusion to the feather-like aspect of the species. My reasons for this, and my present information as to the nature of these plants, may be stated as follows: Schimper, in his “Palæontologie Vegetale” (possibly from inattention to the descriptions or want of access to specimens), doubts the lycopodiaceous character of species ofLycopoditesdescribed in my published papers on plants of the Devonian of America and in my Report of 1871. Of these,L. RichardsoniandL. Matthewiare undoubtedly very near to the modern genusLycopodium.L. Vanuxemiiis, I admit, more problematical; but Schimper could scarcely have supposed it to be a fern or a fucoid allied toCaulerpahad he observed that both in my species and the alliedL. pennæformisof Goeppert, which he does not appear to notice, the pinnules are articulated upon the stem, and leave scars where they have fallen off. When in Belfast in 1870, my attention was again directed to the affinities of these plants by finding in Prof. Thomson’s collection a specimen from Caithness, which shows a plant apparently of this kind, with the same long narrow pinna? 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 crowded and pressed together to admit of being accurately figured or described; but I 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 genusPsilophyton. (Fig. 17,supra.)

[BE]“Canadian Naturalist,” 1878.

The specimen 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. The specimen is thus not a spike of fructification, but a young stem or branch in vernation, and which when unrolled would be of the form of thosepeculiar pinnateLycopoditesof whichL. Vanuxemiiof the American Devonian andL. pennæformisof 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 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 “Report 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 genusLycopodites. On the one hand, they are not unlike the slender twigs ofTaxodiumand 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 concerned, be placed with Algæ of the type of Brongniart’sChondrites obtusus, or the modernCaulerpa plumaria. 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 Devonian, they deserve a generic name, and I proposed for them in my “Paper on Scottish Devonian Plants,” 1878, that ofPtilophyton, a name sufficiently distinct in sound from Psilophyton, and expressing very well their peculiar feather-like habit of growth. The genus was defined as follows:

“Branching plants, the branches bearing long, slender leaves in two or more ranks, giving them a feathered appearance; vernation circinate. Fruit unknown, but analogy would indicate that it was borne on the bases of the leaves or on modified branches with shorter leaves.”

The Scottish specimen above referred to was namedPt. Thomsoni, and was characterised by its densely tufted form and thick branches. The other species known are:Pt. pennæformis, Goeppert, L. Carboniferous;Pt. Vanuxemii, Dawson, Devonian;Pt. plumula, Dawson, L. Carboniferous.

Shumard’sFilicites gracilis, from the Devonian of Ohio, and Stur’sPinites antecedens, from the Lower Carboniferous of Silesia, may possibly belong to the same genus. The Scottish specimen referred to is apparently the first appearance of this form in the Devonian of Europe.

I have at a still later date had opportunities of studying considerable series of these plants collected by Prof. Williams, of Cornell University, and prepared a note in reference to them for the American Association, of which, however, only an abstract has been published. I have also been favoured by Prof. Lesquereux and Mr. Lacoe, of Pittston, with the opportunity of studying the specimens referred toTrochophyllum.

Prof. Williams’s specimens occur in a dark shale associated with remains of land-plants of the generaPsilophyton.Rhodea, &c., and also marine shells, of which a small species ofRhynchonellais often attached to the stems of thePtilophyton. Thus these organisms have evidently been deposited in marine beds, but in association with land-plants.

The study of the specimens collected by Prof. Williams develops the following facts: (1) The 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 pinnæ for the length of one or more inches. (3) The stems curve in such a manner as to indicate a circinate 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 sterns are of this nature. (6) 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 brachiopods to the specimens ofPtilophytonwould seem to indicate that the plant stood erect in the water. (8) Some of the specimens show so much carbonaceous matter as to indicate that the pinnules were of considerable consistency. All these characters are those rather of an aquatic plant than of an animal organism or of a land-plant.

The specimens communicated by Prof. Lesquereux and Mr. Lacoe are from the Lower Carboniferous, and evidently represent a different species with similar slender pitted stems, often partially denuded of pinnules below; but the pinnules are much broader andmore distant. They are attached by very narrow bases, and apparently tend to lie on a plane, though they may possibly have been spirally arranged. On the same slabs are rounded sporangia or macrospores like those ofLepidodendron, but there is no evidence that these belonged toTrochophyllum. 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 float the plant. This would account for many of the peculiarities in the appearance and mode of occurrence of the DevonianPtilophyton, which are readily explained 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 Algæ, though no doubt cryptogamous.

The species ofPtilophytonwill thus constitute a peculiar group of aquatic plants, belonging to the Devonian and Lower Carboniferous 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 isPt. plumula, found by Dr. Honeyman in the Lower Carboniferous of Nova Scotia; but asPt. Vanuxemiiabounds 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 quarters, the following summary is given from descriptions published in the “Journal of the Geological Society of London” (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 probably herbaceous; but there are other species which may have been tree-ferns. Little definite information, however, has, until recently, been obtained with regard to their habit of growth.

The only species known to me in the Devonian of Europe is theCaulopteris Peachiiof 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 genusCaulopteris, of the coal formation.

In my paper on the Devonian of Eastern America (“Quarterly Journal of the Geological Society,” 1862), I mentioned a plant found by Mr. Richardson at Perry, as possibly a species ofMegaphyton, 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.

More recently, in 1869, Prof. Hall placed in my hands an interesting collection from Gilboa, New York, and Madison County, New York, including two trunks surrounded by aërial roots, which I have described asPsaronius textilisandP. Erianus, in my “Revision of the Devonian Flora,” read before the Royal Society.[BF]In the same collection were two very large petioles,Rhachiopteris giganteaandR. palmata, which I have suggested may have belonged to tree-ferns.

[BF]Abstract in “Proceedings of the Royal Society,” May, 1870; also “Report on Erian Plants of Canada,” 1871.

My determination of the species ofPsaronius, 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 existence there of three species of tree-ferns, one of them with aërial 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. Hall’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 the Gilboa specimens are from a bed containing erect stumps of tree-ferns, in the Chemung group of the Upper Devonian, while those from Ohio are from a marine limestone, belonging to the lower part of the Middle Devonian.

1.Caulopteris Lockwoodi, Dawson.—Trunk from two to threeinches 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 preserved. Petioles slender, much expanded at the base, dividing at first in a pinnate manner, and afterwards dichotomously. Ultimate pinnæ with remains of numerous, apparently narrow pinnules.

This stem is probably the upper part of one or other of the species ofPsaroniusfound in the same bed (P. Erianus, Dawson, andP. textilis, Dawson).[BG]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 petioles, 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 somewhat 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 downward 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 fromFig. 24,supra.

[BG]Memoir on Devonian Flora, “Proceedings of the Royal Society,” May, 1870.

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 remains of small pinnæ, or possibly of spines on the margin of the petiole. Other fragments show the division of the frond, at first in a pinnate manner, and subsequently by bifurcation; and some fragments show remains of pinnules, possibly of fertile pinnules. These are very indistinct, but would seem to show that the plant approached, in the form of its fronds and the arrangement of its fructification, to the Cyclopterids of the sub-genusAneimites, one of which (Aneimites Acadica), from the Lower Carboniferous of Nova Scotia, I have elsewhere described as probably a tree-fern,[BH]Thefronds were evidently different from those ofArchæopteris[BI]a genus characteristic of the same beds, but of very different habit of growth. This accords with the fact that there is in Prof. Hall’s collection a mass of fronds ofCyclopteris(Archæopteris) Jacksoni, so arranged as to make it probable that the plant was an herbaceous fern, producing 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 genusCaulopterisor inStemmatopteris; 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 fossilCaulopteris Lockwoodi.

[BH]“Quarterly Journal of the Geological Society,” 1860.

[BI]The genus to which the well-knownCyclopteris(Adiantites)Hibernicusof the Devonian of Ireland belongs.

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 Gaspé Bay, which have not as yet afforded 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 sufficiently perfect for description.

Mr. Lockwood’s collection includes specimens ofPsaronius textilis; and in addition to these there are remains of erect stems somewhat 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 downward, and sometimes terminating in rounded ends. They resemble in form and size the aërial roots ofPsaronius Erianus; and I believe them to be similar roots from a higher part of the stem, and some of them young and not prolonged sufficiently far to reach the ground. This specimen would thus represent the stem ofP. Erianusat a higher level than those previously found. We can thus in imagination 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 namedRhachiopteris punctata. My original specimen was obtained by Prof. Hall from the same horizon in New York.That of Mr. Lockwood is of larger size, but retains no remains of the frond. It must have belonged to a species quite distinct fromCaulopteris Lockwoodi, but which may, like it, have been a tree-fern.

2.Caulopteris antiqua, Newberry.—This is a flattened stem, on a slab of limestone, containing Brachiopods, 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 resemblesCaulopteris Peachii, but is of larger size. It differs fromC. Lockwoodiin 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 generic or subgeneric form not hitherto recognised below the Carboniferous, and having its minute structure in part preserved.

The specimens are, like the last, on slabs of marine limestone of the Corniferous formation, and flattened. One represents an upper portion of the stem with leaf-scars and remains of petioles; another a lower portion, with aërial 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 rounded and sometimes double marginal line, sometimes with a slight depression in the middle. The lower part is irregular, and when most perfect shows seven slender vascular bundles, passing obliquely downward into the stem. The more perfect 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 manner of many modern ferns. Some of the scars show traces of the hippocrepian mark characteristic ofProtopteris; and the arrangement 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. On careful examination, the species is indeed very near to the typicalP. Sternbergii, as figured by Corda and Schimper.[BJ]

[BJ]Corda, “Beiträge,” Pl. 48, copied by Schimper, Pl. 52.

The genusProtopterisof Sternberg, though the original species (P. punctata) appears as aLepidodendronin his earlier plate (Plate 4), and as aSigillaria(S. punctata) in Brongniart’s great work, is a true tree-fern; and the structure of one species (P. Cottai) has been beautifully figured by Corda. The species hitherto described 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 diameter, and is covered with a mass of flattened aërial roots lying parallel to each other, in the manner of thePsaronitesof the coal-formation and ofP. Erianusof the Upper Erian or Devonian.

4.Asteropteris noveboracensis, gen. and sp. n.—The genusAsteropterisis 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 traversed by leaf-bundles of the type of those ofZygopteris.

The only species known to me is represented by a stem 2·5 centimetres in diameter, slightly wrinkled and pitted externally, perhaps by traces of aërial roots which have perished. The transverse section shows in the centre four vertical plates of scalariform or imperfectly 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 cellular tissue filling the angular interspaces. The greatest diameter of this axis is about 1·5 centimetre. Exterior to the axis the stem consists of elongated cells, 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 carbonization. Embedded in this outer cylinder are about twelve vascular 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, apparently 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,[BK]and constituting a very complex and symmetrical form of the group of Palæozoic ferns alliedto the genusZygopterisof Schimper. The central axis alone has a curious resemblance to the peculiar stem described by Unger (“Devonian Flora of Thuringia”) under the name ofCladoxylon mirabile; and it is just possible that this latter stem may be the axis of some allied plant. The large aërial roots of some modern tree-ferns of the genusAngiopterishave, however, an analogous radiating structure.

[BK]Prof. Williamson, to whom I have sent a tracing of the structure, agrees with me that it is new.

The specimen is from the collection of Berlin H. 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 ofLepidodendra, probablyL. ChemungenseandL. primævum.

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 matter 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 maceration of the plant-remains in the sea-water.

In connection with this I may refer to the remarkable facts recently stated by Williamson[BL]respecting the stems known as Heterangium andLyginodendron. 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 Equisetaceæ of the Coal period.

[BL]“Proceedings of the Royal Society,” January 6, 1887.

IV.—On Erian Trees of the Genus Dadoxylon, Unger.(Araucaritesof Goeppert,Araucarioxylonof Kraus.)

Large woody trunks, carbonised or silicified, 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 Permian and Triassic series. The namesAraucaritesandAraucarioxylonare perhaps objectionable, inasmuch as they suppose affinities toAraucariawhich may not exist. Unger’s name, which is non-committal,is therefore, I think, to be preferred. In my “Acadian Geology,” and in my “Report on the Geology of Prince Edward Island,” I have given reasons for believing that the foliage of some at least of these trees was that known asWalchia, and that they may have borne nutlets in the manner of Taxine trees (Trigonocarpum, &c). Grand d’Eury has recently suggested that some of them may have belonged toCordaites, 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 Hartt, who found large trunks, which I afterwards described asDadoxylon Ouangondianum, 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 genusOrmoxylonwas 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 were named by meD. Halli,D. Newberryi, andOrmoxylon Erianum. The three species ofDadoxylonagreed in having composite medullary rays, and would thus belong to the groupPalæoxylonof Brongniart. In the case ofOrmoxylonthis 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, Massachusetts, for some well-preserved specimens of another species from the Genesee shale of Canandaigua, New York. They show small steins 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 toCordaitesorSigillaria. In any case this structure is new, and I have named the speciesDadoxylon Clarkii, after its discoverer. The specimens occur, according to Prof. Clarke, in a calcareous layer which is filled with the minute shells ofStyliola fissurellaof Hall, believed to be a Pteropod; and containing also shells ofGoniatitesandGyroceras. The stems found are only a few inches in diameter, but may be branches of larger trees.

It thus appears that we already know five species of Coniferous trees of the genusDadoxylonin the Middle 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. Goeppert 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 Sandstone of Scotland, and described by Salter and McNab, is of similar character, and probably belongs to the genusDadoxylon. Thus this type of Coniferous tree seems to have been as well established and differentiated into species in the Middle Devonian as in the succeeding Carboniferous.

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 problematical trees which in the previous chapter I have named Protogens (Nematophyton,Celluloxlyon,[BM]Nematoxylon[BN]), thoughAporoxylonof Unger extends, in Thuringia, up to the Upper Devonian (Cypridina schists).

[BM]“Journal of the Geological Society,” May, 1881.

[BN]Ibid., vol. xix, 1863.

V.—Scottish Devonian Plants of Hugh 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 namePsilophyton; and I referred to these in this connection in my earliest description of that genus.[BO]He had also recognised 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. Hooker and Mr. Salter had described some of these remains. More recently Messrs. Peach, Carruthers, and McNab have worked in this field, and still later[BP]Messrs. Jack and Etheridge have summed up the facts and have added some that are new.

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