The stems with this type of sculpturing, are supposed to belong to a group of extinct vegetables, which held an intermediate place between the Sigillariæ, previously described, and the Lepidodendra; together with the latter, and certain true Coniferæ and arborescent ferns, these trees appear to have constituted the principal forests of the Carboniferous epoch. [Illustration: Plate XXV.] PLATE XXV. "Frondose Megaphyton." (_Megaphyton distans_, of Lindley and Hutton's Fossil Flora of Great Britain.) Very large stems not channelled, with regular cicatrices of great size, arranged longitudinally, occur in the sandstone and grits of the Carboniferous formation, and are supposed to belong to a tribe of extinct plants, more nearly allied to the arborescent ferns of our tropical climes, than to any other existing trees. The specimen figured is part of a stem ten feet in length, from a quarry near Rowmarsh in Yorkshire. This stem has a coarse fibrous surface, furrowed longitudinally; the cicatrices left by the shedding of the leaves are of a horseshoe shape with the points directed upwards. This group of stems has been separated by writers on fossil botany into several genera, as _Bothrodendron_, _Ulodendron_, &c.[21] In some of these the scars are five inches in diameter. [Footnote 21: See Dr. Buckland's Bridgewater Essay, plate 56.] There are many fine examples of these fossils in the British Museum. [Illustration: Plate XXVI.] PLATE XXVI. "Lepidodendron, or Scaly-tree." (_Aphyllum asperum_, Rough Aphyllum, of Artis.) "The Lepidodendra (Scaly-trees) are a tribe of plants whose remains abound in the Coal formation, and rival in number and magnitude the Calamites and Sigillariæ previously described. The name is derived from the imbricated or scaly appearance of the surface, occasioned by the little angular scars left by the separation of the leaves. Some of these trees have been found almost entire, from their roots to the topmost branches. One specimen, forty feet high, and thirteen feet in diameter at the base, and divided towards the summit into fifteen or twenty branches, was discovered in the Jarrow coal-mine, near Newcastle.[22] [Footnote 22: Wonders of Geology, sixth edition, vol. ii. p. 722.] "The foliage of these trees consists of simple linear leaves, spirally arranged around the stem, and which appear to have been shed from the base of the tree with age. The markings produced by the attachment of the leaves are never obliterated, and the twigs and branches are generally found covered with foliage. The originals are supposed by M. Adolphe Brongniart, notwithstanding their gigantic size, to have been closely related to the Lycopodia, or Club-mosses."[23] [Footnote 23: Medals of Creation, p. 144.]