DESCRIPTION OF SPECIES. PP. ,") 



)D 



when it is present. It seems to be caused by the extension 

 of the epidermis of the leaflets over the rachis. The nerves 

 are immersed in the dense leaf-substance, which mav be 

 pulled off from the stone in flakes, leaving an imprint in 

 which no sign of the lateral nerves appears. The nerves 

 of the broader and larger pinnules appear to fork once, 

 while those of the narrower and longer pinnules, which 

 appear in the middle portions of the frond, seem simple. 

 They are usually so enclosed in the dense leaf-substance as 

 to betray their presence by creases, which no doubt are 

 much stronger than the true nerves. As we could see only 

 these creases, indicating the course of the nerves, we have 

 depicted them in the lateral nerves given in the figures. 

 The nervation as thus determined, appears to agree with 

 that given by Weiss. We cannot agree with Weiss in re- 

 ferring the plant to Aletlwpteris, as it is entirely different 

 from any species of that genus known to us. 



This is the only species of true Callipteris that has ever 

 been found in the Appalachian Coal Field, and its appear- 

 ance marks an important change in the flora of the horizon 

 containing it. The other species from this field attributed 

 to Callipteris are either Alethopterids, like A. Sullivanti, 

 or plants of the Pecopteris type, and belonging to Callip- 

 teridium. 



In Europe this plant is regarded as a characteristic Per- 

 mian species. 



Callipteridium, Weiss. 



Dr. Weiss has established under the name of Callipter- 

 idium a genus to include plants which, with the facies of 

 Pecopteris, have a nervation resembling that of Neurop- 

 teris. Schimper gives the following as the generic charac- 

 ter : "Median-nerve of the pinnules, strong, vanishing; 

 secondary nerves obliquely spreading, simply or doubly 

 forked, parallel to each other." 



These plants are amongst the finest found in the Upper 

 Carboniferous strata, and in W. Va. are peculiar to them, 



