The Calamite is another plant in which the Coal abounds. Its true botanical character is not yet clearly ascertained; but it bears a general resemblance, except for its gigantic dimensions, to the common Horse-tail of our swamps and marshy grounds. It is a reed-like, jointed stem, sometimes thirty feet in length, hollow within, and curiously jointed without. [Illustration: Fig. 25.--Lepidodendron Sternbergii; a Fossil Tree, 39 feet high. From a Coal Mine near Newcastle.] Scarcely less conspicuous than the Sigillaria, the Fern, and the Calamite, is the Lepidodendron or Scaly Tree, one of the most curious and interesting among the plants of the Coal-bearing period. Like the Sigillaria and the Calamite, it has been, and still is, a puzzle to the student of Botany. But it needs not the eye of science to see that it is unmistakably a stately forest tree, shut up in the Crust of the Earth, encased in a solid framework of indurated Shale, or Sandstone, or Coal, as the case may be, and overlaid with massive strata of rock hundreds of feet in thickness. Such a specimen as that represented in our woodcut was laid bare some years ago in Yarrow Colliery, near Newcastle. [Illustration: Fig. 26 Lepidodendron Elegans. Portion of Stem and branches; Coal Mine, Newcastle.] In the same neighborhood was found a portion of the stem and branches of another variety, Lepidodendron Elegans, which will enable the reader to form a more complete idea of the appearance presented by this ancient tree as it stood in its primeval forest. An unusually favorable illustration of our present subject may be seen at the colliery of Treuil, in France, not far from the city of Lyons. The beds of Coal are overlaid by a kind of slaty sandstone, ten feet thick; and this sandstone is traversed by the vertical stems of enormous petrified plants, chiefly Calamites. Here, then, to all appearance, we have an ancient forest enveloped in sandstone. We must suppose that the forest was submerged while the trees were still erect; that in this condition it received the sedimentary deposits carried down by the current of some great river; and finally, that these deposits were, in the course of ages, compacted into sandstone by a process already explained. It would seem that after the sandstone had been partially, at least, consolidated, it was subjected to a sliding movement here and there, by which the continuity of the stems was broken; the upper part being pushed on one side, as shown in our Figure. [Illustration: Fig. 27.--Section of a Coal sandstone at Treuil, near Lyons. Showing the erect position of Fossil Trees. (Alex. Brongniart.)]