DESCRIPTION OF SPECIES. PP. 77 



This plant resembles P. arborescens somewhat; but the 

 union of the pinnules, the nervation, and the insertion of the 

 pinnules distinguish it from that species. It was evidently 

 a very fleshy plant, as the nerves are usually so deeply 

 buried that they are seen with difficulty. 



Habitat.— Roof shales of the Waynesburg Coal, West 

 Union, West Virginia. 



Pecopteris Heeriana, Sp. nov., PL XXY, Figs. 3-7. 



(Frond, tripinnate; secondary pinnse, alternate, somewhat 

 flexuous, going off at nearly a right angle ; pinnules, 

 slightly falcate, remotely placed and decurrent on the 

 rachis, so as to render it distinctly winged ; lowest j^innule 

 on the lowest side, often inserted partly on the principal 

 rachis ; pinnules on the lower portion of the plant, notched 

 or lobed ; mid-nerve, well defined and extending to the apex 

 of the pinnule ; lateral nerves, going off at an acute angle, 

 forming 4 or 5 pairs, simple ; fructification, composed of 

 numerous shield-shaped sori covering the surface of the 

 pinnule. ) 



The texture of the pinnules is thick and leather-like, usu- 

 ally obscuring the nerves. The plant presents a type un- 

 usual in the Carboniferous strata, but characteristic of the 

 Rhaetic flora. It belongs to Schimper's section of Pecop- 

 teris acrostichides, and recalls forcibly the appearance of 

 Pecopteris Williamsoni,Brongt., both in the form of the pin- 

 nules, and in the character of thefructiflcation. Named in 

 honor of Dr. Oswald Heer of Zurich. 



Habitat, — Roof -shales of the Waynesburg Coal, Cass- 

 ville, W. Va. 



Pecopteris tenuinerms. Sp. nov., PI. XXYIII, Figs. 1-4. 



(Frond, trij)innate; primary rachis, strong, and somewhat 

 rigid ; secondary pinnffi, linear-lanceolate, alternate, closely 

 placed, becoming gradually shorter towards the apex of the 

 primary pinna, thus giving this a triangular outline ; pin- 

 nules very shoi't, narrow and alternate, the lowest one, on 

 the lower side, always heteromorphous, it having a crenu- 

 late margin, and being larger than the rest ; pinnules to- 



