Returning to the more special subject of this work, I may remark that the lepidodendroid trees and the ferns, both the arborescent and herbaceous kinds, are even more richly represented in the Carboniferous than in the preceding Erian, I must, however, content myself with merely introducing a few representatives of some of the more common kinds, in an appended note, and here give a figure of a well-known Lower Carboniferous lepidodendron, with its various forms of leaf-bases, and its foliage and fruit ([Fig. 43]), and a similar illustration of an allied generic form, that known as Lepidophloios[CB] ([Fig. 44]).

[CB] For full descriptions of these, see “Acadian Geology.”

Fig. 41.—Beds associated with the main coal (S. Joggins, Nova Scotia). 1, Shale and sandstone—plants with Spirorbis attached; rain-marks (?). (2, Sandstone and shale, eight feet—erect Calamites; 3, Gray sandstone, seven feet; 4, Gray shale, four feet—an erect coniferous (?) tree, rooted on the shale, passes up through fifteen feet of the sandstones and shale.) 5, Gray sandstone, four feet. 6, Gray shale, six inches—prostrate and erect trees, with rootlets, leaves, Naiadites, and Spirorbis on the plants. 7, Main coal-seam, five feet of coal in two seams. 8, Underclay, with rootlets. Fig. 42.—Erect Sigillaria, standing on a coal-seam (S. Joggins, Nova Scotia).

Another group which claims our attention is that of the Calamites. These are tall, cylindrical, branchless stems, with whorls of branchlets, bearing needle-like leaves and spreading in stools from the base, so as to form dense thickets, like Southern cane-brakes ([Fig. 46]). They bear, in habit of growth and fructification, a close relation to our modern equisetums, or mare’s-tails, but, as in other cases we have met with, are of gigantic size and comparatively complex structure. Their stems, in cross-section, show radiating bundles of fibres, like those of exogenous woods, yet the whole plan of structure presents some curious resemblances to the stems of their humble successors, the modern mare’s-tails. It would seem, from the manner in which dense brakes of these Calamites have been preserved in the coal-formation of Nova Scotia, that they spread over low and occasionally inundated flats, and formed fringes on the seaward sides of the great Sigillaria forests. In this way they no doubt contributed to prevent the invasion of the areas of coal accumulation by the muddy waters of inundations, and thus, though they may not have furnished much of the material of coal, they no doubt contributed to its purity. Many beautiful plants of the genera Asterophyllites and Annularia are supposed to have been allied to the Calamites, or to have connected them with the Rhizocarps. The stems and fruit of these plants have strong points of resemblance to those of Sphenophyllum, and the leaves are broad, and not narrow and angular like those of the true Calamites ([Fig. 45]).

Fig. 43.—Lepidodendron corrugatum, Dawson, a tree characteristic of the Lower Carboniferous, A, Restoration. B, Leaf, natural size, C, Cone and branch, D, Branch and leaves, E. Various forms of leaf-areoles. F, Sporangium, I, L, M, Bark, with leaf-scars, N, Bark, with leaf-scars of old stem, O, Decorticated stem (Knorria).