212 LL. Lesquereux on the Coal Formations of North America. 
in an acute angle, dichotomous; branches simple or forking, 
more or less arched. Pecopteris Pluckneti Brgt., was already 
genus Sphenopteris than with the Pecopteridee. We have only 
two American species referable to this section, and they are of 
course mentioned with the genus Sphenopteris. 
It would be out of place to examine critically now the other 
genera proposed for the classification of the Pecopteridea. A few 
only, on which our American specimens furnish some interest 
ing data, can be mentioned here. ; 
Géppert has separated his genus Diplawites, especially from 
the pinnules united nearly in their whole length, and the mele 
nerve pinnately branching, with simple veinlets a little curv 
inwards and ascending to the margin of the leaflets. Mr. But 
bury, in his examination of some fossil ferns of Frostburg, Md, 
(Quart. Journ. of the Geol. Soc. of London, vol. 2, p. 82,) bas 
ts. 
that case the species has exactly the nervation and the ene 
irregular impressions from the fruit-dots, placed under the 
