I have already referred to the close resemblance which certain Cycadaceous genera bear to certain of the fern family. In at least two species of Pterophyllum,—P. comptum and P. minus,—the divisions of the leaflets seem little else than accidental rents in a simple frond; in P. Nelsoni they are apparently nothing more; and similar divisions, evidently, however, the effect of accident, and less rounded at their extremities than in at least P. comptum, we find exhibited by some of the Helmsdale specimens of Tæniopteris (See [Fig. 142], p. 488.) But whatever the nature of these simple fronds, they seem to impart much of its peculiar character, all the world over, to the flora of the Oolitic ages.
PECOPTERIS OBTUSIFOLIA.
| Fig. 144. | Fig. 145. PACHYPTERIS. |
The compound ferns of the formation are numerous, and at least proportionally a considerable part of them seem identical in species with those of the Oolite of England. (See [Fig. 143.]) Among these there occur Pecopteris Whitbiensis, Pecopteris obtusifolia, Pecopteris insignis,—all well marked English species; with several others. It has, besides, its apparent ferns, that seem to be new—([Fig. 144])—that are at least not figured in any of the fossil floras to which I have access,—([Fig. 145]),—such as a well defined Pachypteris, with leaflets broader and rounder than the typical P. lanceolata, and a much stouter midrib; a minute Sphenopteris too, and what seems to be a Phlebopteris, somewhat resembling P. propinqua, but greatly more massive in its general proportions. The equisetacea we find represented in the Brora deposits by Equisetum columnare,—a plant the broken remains of which occur in great abundance, and which, as was remarked by our President many years ago, in his paper on the Sutherlandshire Oolite, must have entered largely into the composition of the bed of lignite known as the Brora Coal. We find associated with it what seems to be the last of the Calamites,—Calamites arenaceus,—a name, however, which seems to have been bestowed both on this Oolitic plant and a resembling Carboniferous species. The deposit has also its Lycopodites, though, from their resemblance in foliage to the conifers, there exists that difficulty in drawing the line between them to which I have already adverted. One of these, however, so exactly resembles a lycopodite of both the Virginian and Yorkshire Oolite,—L. uncifolius,—that I cannot avoid regarding it as specifically identical; and it seems more than doubtful whether the stem which I have placed among the conifers is not a lycopodite also. It exhibits not only the general outline of the true club moss, but, like the fossil club mosses too, it wants that degree of ligniferous body in the rock which the coniferous fossils almost always possess. Yet another of the organisms of the deposit seems to have been either a lycopodite or a fern. Its leaflets are exceedingly minute, and set alternately on a stem slender as a hair,—circumstances in which it resembles some of the tiny lycopodites of the tropics, such as Lycopodium apodium. I must mention, however, that the larger plant of the same beds which I have placed beside it, and which resembles it so closely that my engraver finds it difficult to indicate any other difference between them than that of size, appears to be a true fern, not a lycopodium. To yet another vegetable organism of the system,—an organism which must be regarded, if I do not mistake its character, as at once very interesting and extraordinary, occurring as it does so low in the scale, and bearing an antiquity so high,—I shall advert, after a preliminary remark on a general characteristic of the flora to which it belongs, but to which it seems to furnish a striking exception.
PHLEBOPTERIS.