CONIFER TWIGS.
Twigs which exhibit the foliage of these ancient conifers seem to be less rare in our Scotch deposits than in those of England of the same age. My collection contains fossil sprigs, with the slim needle-like leaves attached, of what seem to be from six to seven different species; and it is worthy of notice, that they resemble in the group rather the coniferæ of the southern than those of the northern hemisphere. One sprig in my collection seems scarcely distinguishable from that of the recent Altingia excelsa; another, from that of the recent Altingia cunninghami. Lindley and Hutton figure in their fossil flora a minute branch of Dacrydium cupressinum, in order to show how nearly the twigs of a large tree, from fifty to a hundred feet high, may resemble some of the "fossils referable to Lycopodiaceæ." More than one of the Oolitic twigs in my collection are of a resembling character, and may have belonged either to cone-bearing trees or to club mosses. Respecting, however, the real character of at least one of the specimens,—a minute branch from the Lias of Eathie, with the leaflets attached,—there can be no mistake. The thicker part of the stem is in such a state of keeping, that it presents to the microscope, in a sliced preparation, the internal structure, and exhibits, as in recent coniferous twigs of a year's growth, a central pith, a single ring of reticulated tissue arranged in lines that radiate outwards, and a thin layer of enveloping bark. Nothing, then, can be more certain than that this ancient twig, which must be accepted as representative of the foliage of whole forests of the Secondary ages in Scotland, formed part of a conifer of the Lias; and the foliage of several of the other twigs, its contemporaries, though I have failed to demonstrate their true character in the same way, bear a scarce less coniferous aspect. The cones of the period, from the circumstance that they are locked up in a hard limestone that clings closely around their scales, and from the further circumstance that the semi-calcareous lignite into which they are resolved is softer and less tenacious than the enclosing matrix, present, when laid open, not their outer surfaces, but mere sections of their interior; and give, in consequence, save in their general proportions and outline, but few specific marks by which to distinguish them. We see, however, in some cases in these sections what would be otherwise unseen,—the flat naked seeds lying embedded in their hollow receptacles between the scales, and in as perfect a state of keeping as the seeds of recent pines that had ripened only a twelvemonth ago. Had not the vitality of seeds its limits in time, like life of all other kinds, one might commit these perfect fossil germs to the soil, in the hope of seeing the old extinct forests called, through their agency, a second time into existence. Of three apparent species of cones which occur in the Eathie Lias, the smallest seems to have resembled in size and appearance that of the Scotch fir; the largest, which consisted from bottom to top, as seen in section, of from nine to ten scales, appears to have been more in the proportions of the oblong oval cones of the spruce family; while a cone of intermediate length, but of considerably greater breadth, assumed the rounded form of the cones of the cedar. I have found in the same deposit what seems to be the sprig of a conifer, with four apparently embryo cones attached to it in the alternate order. These are rather more sessile than the young cones of the larch; but the aspect of the whole is that of a larch twig in early summer, when the minute and tender cones, possessed of all the beauty of flowers, first appear along its sides.
ZAMIA.
ZAMIA.