With the leaves of the Eathie Zamia, we find, in this northern outlier of the Lias, cones of a peculiar form, which, like the leaves themselves, are still unfigured and undescribed, and some of which could scarce have belonged to any coniferous tree. In one of these ([Fig. 138]), the ligneous bracts or scales, narrow and long, and gradually tapering till they assume nearly the awl-shaped form, cluster out thick from the base and middle portions of the cone, and, like the involucral appendages of the hazel-nut, or the sepals of the yet unfolded rose-bud, sweep gracefully upwards to the top, where they present at their margins minute denticulations. In another species the bracts are broader, thinner, and more leaf-like: they rise, too, more from the base of the cone, and less from its middle portions; so that the whole must have resembled an enormous bud, with strong woody scales, some of which extended from base to apex. The first described of these two species seems to have been more decidedly a cone than the other; but it is probable that they were both connecting links between such leathern seed-bearing flowers as we find developed in Cycas revoluta, and such seed-bearing cones as we find exemplified in Zamia pungens. The bud-like cone, however, does not seem to have been that of a Cycadaceous plant, as it occupied evidently not a terminal position on the plant that bore it, like the cones of Zamia or the flowers of Cycas, but a lateral one, like the lateral flowers of some of the Cactus tribe. Another class of vegetable forms, of occasional occurrence in the Helmsdale beds, seems intermediate between the Cycadaceæ and the ferns: at least, so near is the approach to the ordinary fern outline, while retaining the stiff ligneous character of Zamia, that it is scarce less difficult to determine to which of the two orders of plants such organisms belonged, than to decide whether some of the slim graceful sprigs of foliage that occur in the rocks beside them belonged to the conifers or the club mosses. And I am informed by Sir Charles Lyell, that (as some of the existing conifers bear a foliage scarce distinguishable from that of Lycopodiaceæ), so a recently discovered Zamia is furnished with fronds that scarce differ from those of a fern. Even Zamia pectinata may, as Sternberg remarks, have been a fern. Lindley and Hutton place it merely provisionally among the Cycadaceæ, in deference to the judgment of Adolphe Brogniart, and point out its resemblance to Polypodium pectinatum; and a small Helmsdale frond which I have placed beside it bears the impress of a character scarce less equivocal. The flora of the Oolite was peculiarly a flora of intermediate forms.
We recognize another characteristic of our Oolitic flora in its simple-leaved fronds, in some of the species not a little resembling those of the recent Scolopendrium, or Hart's-Tongue fern,—a form regarded by Adolphe Brogniart as peculiarly characteristic of his third period of vegetation. These simple ferns are, in the Helmsdale deposits, of three distinct types. There is first a lanceolate leaf, from two and a half to three inches in length, of not unfrequent occurrence, which may have formed, however, only one of the four leaflets, united by their pseudo-footstalks, which compose the frond of Glossopteris,—a distinctive Oolitic genus. There is next a simple ovate lanceolate leaf, from four to five and a half inches in length, which in form and venation, and all save its thrice greater size, not a little resembles the leaflets of a Coal Measure neuropteris,—N. acuminata. And, in the third place, there are the simple leaves that in general outline resemble, as I have said, the fronds of the recent Hart's-Tongue fern (Scolopendrium vulgare), except that their base is lanceolate, not cordate. Of these last there are two kinds in the beds, representative of two several species, or, as their difference in general aspect and detail is very great, mayhap two several genera. The smaller of the two has a slender midrib, depressed on its upper side, and flanked on each side by a row of minute, slightly elongated protuberances, but elevated on the under side, and flanked by rows of small but well marked grooves, that curve outwards to the edges of the leaf. The larger resemble a Tæniopteris of the English and Continental Oolites, save that its midrib is more massive, its venation less at right angles with the stem, its base more elongated, and its size much greater. Some of the Helmsdale specimens are of gigantic proportions. From, however, a description and figure of a plant of evidently the same genus,—a Tæniopteris of the Virginian Oolite, given by Professor W.B. Rogers of the United States,—I find that some of the American fronds are larger still. My largest leaf from Helmsdale must have been nearly five inches in breadth; and if its proportions were those of some of the smaller ones of apparently the same species from the same locality, it must have measured about thirty inches in length. But fragments of American leaves have been found more than six inches in breadth, and whose length cannot have fallen short of forty inches. The Tæniopteris, as its name bears, is regarded as a fern. From, however, the leathern-like thickness of some of the Sutherland specimens,—from the great massiveness of their midrib,—from the rectilinear simplicity of their fibres,—and, withal, from, in some instances, their great size,—I am much disposed to believe that in our Scotch, mayhap also in the American species, it may have been the frond of some simple-leaved Cycas or Zamia. But the point is one which it must be left for the future satisfactorily to settle; though provisionally I may be permitted to regard these leaves as belonging to some Cycadaceous plant, whose fronds, in their venation and form, resembled the simple fronds of Scolopendrium, just as the leaves of some of its congeners resembled the fronds of the pinnate ferns.
