354 Systematic Paleontology 



This species which is based upon infrequent and insufficient material 

 may simply be a variant of the common Ctenopteris insignis from which 

 it shows but minor differences. 



Occurrence. — Patuxent Formation. Near Potomac Eun, Chinka- 

 pin Hollow (?), Virginia. 



Collection. — U. S. National Museum. 



Ctenopteris longifolia Fontaine 



ctenopteris longifolia Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 1889, 

 p. 159, pi. Ixvii, fig. 5. 



Description. — " Frond unknown ; rachis of the ultimate pinna3 very 

 broad, but not apparently very woody; pinnules placed very remotely, 

 opposite, going off obliquely, very long, linear, narrowed gradually and 

 slightly towards the base and slightly decurrent, tips not seen; nerves 

 not well made out, but apparently several, departing independently from 

 the rachis and forking near the base ; the branches, so far as seen, simple, 

 and nearly parallel.'^ — Fontaine, 1890. 



This species was based upon the single specimen figured, which is the 

 only one ever discovered, hence little can be added to the foregoing 

 diagnosis. It seems probable that it is simply a variant of one of the 

 other species of Ctenopteris which occur in the same layers, as for 

 example Ctenopteris angustifolia. 



Occurrence. — Patuxent Formation. Fredericksburg, Virginia. 



Collection. — IT. S. ISTational Museum. 



Genus ZAMIOPSIS Fontaine 

 [Mon. U. S. Geol. Surv., vol. xv, 1890, p. 160] 



This genus was established by Fontaine for certain supposed fem-like 

 remains from the older Potomac which were characterized as follows : 



" Fronds large, bipinnate to tripinnatifid ; leaf -substance leathery and 

 thick, covered with a dense, durable epidermis; rachises strong, rigid, 

 and keeled on the lower surface, often with ridges or raised margins on 



