16 Contrihitions towards Establishing the General Character 



the ribs, the fuiTOws, and the scars on their surface ; specimens shewing 

 the original or outer surface of the cuticle are rather uncommon ; when 

 this surface is exhibited, a line of scars may be seen running up the 

 middle of each rib, and possessing a character which distinguishes them 

 from those already mentioned under the name of vascular scars, and 

 which character is entirely due to the presence of the cuticle. On the 

 North Biddick specimens, from their being decorticated, we merely ob- 

 serve the scars left by the vessels which proceeded from the internal 

 vascular system into the leaves ; whereas^ on those specimens which still 

 retain the cuticle, we observe not only the vascular scars, but likewise 

 the impressions left by the fallen leaves. Hence, the latter have been 

 termed leaf-scars. Corticated examples of Sigillaria shew each of these 

 impressions to consist of a defined border surrounding an area, in which 

 are situated the triple series of scars left by the vessels previously men- 

 tioned.* The leaf-scars in young branches of the common ash and the 

 plane-tree offer a good illustration of those under consideration. 



The remains of Sigillaria are generally found very much flattened, 

 and consequently the leaf-scars seldom shew any appearance of standing 

 out in relief; this, however, it would appear was not the case originally, 

 at least in some species, for I have seen a beautiful specimen belonging 

 to Mr Dawes, preserved in ironstone, having the lower margin of the 

 scars projecting about a quarter of an inch beyond the level of the ribs. 

 The details already given as to the internal structure of Sigillaria 

 elegans shew that its cuticle is composed of two distinct layers, the inner- 

 most one oi prosenchyma, and the outermost of parenchyma, or ordinary 

 cellular tissue ; from this peculiarity it may be supposed that the 

 cuticle is in some cases separable into two portions, and that single spe- 

 cimens of Sigillaria ought to be found, shewing various surfaces of the 

 cuticle. As yet, I have not seen this in any of the specimens which 

 have come under my notice, but I strongly suspect that some in this state 

 are figured in Brongniart's ''History of Vegetable Fossils." I will 

 revert to those shortly. The cuticle of Lepidodendron, according to Mr 

 Witham,t is similarly constituted, and in confirmation of this, it may 

 be mentioned, that I have seen corticated specimens of this genus 

 having the outer surface of both layers of the cuticle exposed.! Had 

 Steinhauer been aware of the compound nature of the cuticle of Lepido • 



• The triple nature of the vascular scars, is decidedly more obvious in corti- 

 cated specimens than in those which are decorticated. 



t " The internal structure of Fossil Vegetables found in the Carboniferous and 

 Oolitic deposits of Great Britain, described and illustrated," 4to, 1 833. 



X The specimen of Lepidodendron, figured by Steininger, appears to exhibit 

 the inner surface of each layer of the cuticle, and also an impression of the outer 

 surface of the outermost layer. Vide " Geognostische Beschreibuug des Landes 

 zwischen die Untern Saar und dem Rheine," 1840. 



