FOSSIL I'LOBA. 69 



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 Sigillarice 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.' 



" 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, notwith- 

 standing their gigantic size, to have been closely related to the Lycopodia, or Club-mosses."' 



Associated with the stems of Lepidodendra, and oftentimes imbedded in masses of their 

 foliage, and in some instances attached to the extremities of the branches, are numerous oblong 

 or cylindrical scaly cones, garnished with leaves : an imjjerfect specimen is figured in Plate IX. 

 fig. 1, and the vertical section of another in Plate III. fig. 6. These cones have received the name 

 oi Lepidostrobi (Scaly-cones), and are the seed-vessels or fruits of the Lepidodendra.' 



These fossils often form the nuclei of the ironstone nodules from Coalbrook Dale, and are 

 invested with a pure white hydrate of alumina ; the leaflets, or more properly bractew, are often 

 replaced by galena, or sulphuret of lead, giving rise to specimens of great beauty and interest, as 

 examples of the electro-chemical changes which these fruits of the carbonifei'ous forests have 

 undergone. 



The fossils figured in this Plate, are portions of a stem eleven feet in length, from near 

 Hoyland, Yorkshire. Fig. 1, is from the upper part, and shows the carbonized scales attached ; 

 fig. 2, represents part of the lower end, in which the scales are decorticated, from the adhesion of 

 the bark to the surrounding shale. 



A. Shows the cicatrix, with its transverse gland that connects the scale, in the upper part 



of the trunk. 



B. Exposes the interstice between the scales in the lower portion of the stem. 



C. A section of the hollow cicatrix. 



' Wonders of Geology, sixth edition, vol. ii. p. 722. ' Medals of Creation, p. 144. 



^ See Medals of Creation, p. 147, and lign. 31, p. 149. 



