1874.] . Fossil Plants of the Coal-measures. 249 



these bundles in recent petioles may be represented by the letters H, T, 

 U, and X. As a general rule, the secondary bundles are given off from 

 that part of the primary one which happens to be nearest to the secondary 

 rachis to be supplied. Thus in some cases the upper arms of the X will 

 merely be prolonged and their ends detached ; in other cases a loop pro- 

 jects from the side of one or both arms of the IT, 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 Y form the gutter- 

 shaped bundle (en gouttiere) of M. Trecul. This is the plant to which, on 

 a previous occasion, the author proposed to assign the generic name of 

 Edmxylon (Proc. Eoy. Soc. vol. xx. p. 438). The vessels are chiefly 

 reticulate, with some of the barred and spiral types. The bark con- 

 sists 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 sclerenchyrna 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 trans- 

 verse 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 intercellular 

 lacunae. Numerous fragments of the terminal rachis of the above plant 

 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 Pe- 

 copteris, which are very abundant in the Oldharn nodules; but later 

 researches have led to the conclusion that the plant has been a Spheno- 

 pteris, closely allied to, if not identical with, the 8. 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 proposed 

 (' Proceedings of the Literary and Philosophical Society of Manchester/ 

 Jan. 9, 1872) to give the name of Stauropteris Oldhamia. 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 central point of conjunction. The same kind of cellular tissue sur- 

 rounds the bundle, forming a thin layer, which passes rapidly into a very 



