On the Fossil Plants of the Coal-measures. 223 



ends detached ; in other eases a loop projects from the side of one 

 or both arms of the U, and becomes detached as a ring. 



The first petiole, described under the name of Rachiopteris aspera, 

 is one in which transverse sections of the central vascular bundle 

 exhibit modifications of the H form at its base, separating into 

 two contiguous bundles higher up, and ultimately reverting to the 

 V form — the gutter-shaped bundle {en gouttiere) of M. Trecul. 

 This is the plant to which, on a previous occasion, the author pro- 

 posed to assign the generic name of Edraxylon (Proc. Boy. JSoc. 

 vol. xx. p. 438). The vessels are chiefly reticulate, with some 

 of the barred and spiral types. The bark consists of a delicate 

 inner parenchyma, the cubical cells of which are arranged vertically. 

 This is enclosed in a coarser middle parenchyma ; and the whole 

 is surrounded by an outer layer, composed of intermingled paren- 

 chyma and prosenchyma, the latter being disposed in vertical 

 fibrous bands, having wedge-shaped transverse sections, and being 

 modifications of the sclerenchyma of authors. The outer surface of 

 the bark is covered with innumerable little, obtuse, projecting 

 cellular appendages, which are obviously abortive hairs. These 

 appendages are relatively larger in the smaller rachis than in the 

 larger petioles. In very young petioles transverse bands of small 

 consolidated cells traverse the bark at numerous points, reminding 

 us of the similar conditions seen in the Heterangium Grievii, 

 described in a previous memoir. In the larger petioles these 

 cellular bands have disappeared, and left in their places large inter- 

 cellular lacunae. Numerous fragments of the terminal rachis of 

 the above plaut have been obtained with the leaflets attached. 

 For a long time the author believed that he could identify these 

 with the detached leaflets of a Pecopteris which are very abundant 

 in the Oldham nodules ; but later researches have led to the 

 conclusion that the plant has been a Sphenopteris, closely allied 

 to, if not identical with, the S. Hoeninghausi of Brongniart. The 

 author proposes the provisional name of Rachiopteris aspera for 

 the above plant. 



The next petiole described is one to which Mr. Binney pro- 

 posed (' Proceedings of the Literary and Philosophical Society of 

 Manchester,' Jan. 9, 1872) to give the name of Stauropteris Old- 

 hamia. This is one of the plants of which the vascular bundle, 

 when seen in transverse section, exhibits the appearance of the 

 letter X. The vessels composing this bundle are barred ones ; 

 they are sometimes grouped in four slightly coherent clusters, 

 with some delicate, vertically elongated cells in or near their cen- 

 tral point of conjunction. The same kind of cellular tissue sur- 

 rounds the bundle, forming a thin layer, which passes rapidlv into 

 a very thick layer of coarse prosenchyma, and which has evidently 

 been hard and woody, as in many of the recent Adiantums. 

 Towards the upper part of the petiole the vascular bundle becomes 

 distinctly consolidated into a single cluster of crucial form ; it then 

 passes into a somewhat trifid form, and ultimately into a small 

 cylindrical one. This petiole has branched much more freely than 



