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

FIG. 41.-Beds associated with the main coal (S. Joggins, Nova Scotia). 1, Shale and sandstone-plants with Spirorbis attached; rainmarks (). (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 Spiror bis on the plants. 7, Main _coal-seam, five feet of coal in two seams. 8, Underclay, with rootlets.

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* (Fig. 44).

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

*For full descriptions of these, see "Acadian Geology."

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 radi

ating 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 contrib

uted 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).

No one has done more than my friend Dr. William

FIG. 43.-Lepidodendron corrugatum, Dawson, a tree characteri Lower Carboniferous. A, Restoration. B, Leaf, natural size. and branch. D, Branch and leaves. E, Various forms of le F, Sporangium. 1, L, M, Bark, with leaf-scars. N, Bark, scars of old stem. ó, Decorticated stem (Knorria).

FIG. 44.-Lepidophloios Acadianus, Dawson, a lepidodendroid tree of the coal-formation. A, Restoration. в, Portion of bark (two thirds natural size). o, Ligneous surface of the same. F, Cone (two thirds natural size). G, Leaf (natural size). K, Portion of woody cylinder, showing outer and inner series of vessels magnified. L, Scalariform vessels (highly magnified). M, Various forms of leaf-scars and leaf-bases (natural size).

son, of Manchester, to illustrate the structure of Calamites, and he has shown that these plants, like other cryptogams of the Carboniferous, had mostly stems with regular fibrous wedges, like those of exogens. The structure of the stem is, indeed, so complex, and differs so much in different stages of growth, and different states of preservation, that we are in danger of falling into the greatest confusion in classifying these plants. Sometimes what we call a Calamite is a mere cast of its pith showing longitudinal striæ and constrictions at the nodes. Some

FIG. 45.-Asterophyllites, Sphenophyllum, and Annularia. A, Asterophyllites trinerne. A1, Leaf enlarged. B, Annularia sphenophylloides. B, Leaf enlarged. c, Sphenophyllum erosum. c1, Leaflet enlarged. 02, Scalariform vessel of Sphenophyllum. D, Pinnularia ramosissima, probably a root.

times we have the form of the outer surface of the woody cylinder, showing longitudinal ribs, nodes, and marks of the emission of the branchlets. Sometimes we have the outer surface of the plant covered with a smooth bark showing flat ribs, or almost smooth, and having at the nodes regular articulations with the bases of the verticil