198 Annals of the Carnegie Museum. 



from any one locality was secured in Neshannock Creek at Eastbrook, 

 Lawrence County. 



35. Pleurobema aesopus (Green). 



The type-locality is Pittsburgh (Green). Recorded in Harn's list 

 from western Pennsylvania ; in Rhoads' list from the Ohio and Beaver. 



There is a specimen in the Carnegie Museum from the Mononga- 

 hela at Charleroi, Washington County (Ehrmann Collection), and the 

 writer has found it sparingly in the Ohio in Beaver County, and more 

 abundantly in the Allegheny in southern Armstrong County. 



36. Quadrula undulata (Barnes). 



It is not mentioned in Harn's list, but occurs in Clapp's list from 

 Allegheny County. Rhoads' U. plicatus from the Ohio and Beaver is 

 this species. 



It is abundant all over the Beaver drainage, chiefly so in the Mahon- 

 ing and Shenango Rivers, and formerly occurred in Connoquenessing 

 Creek. It is rather frequent in the Ohio in Beaver County. It is 

 unknown from the Monongahela, but a single half shell was found in 

 the Cheat River in Fayette County. It is present in the upper Mo- 

 nongahela drainage in West Virginia, judging from specimens in the 

 Carnegie Museum. In the Allegheny River in Armstrong and 

 Venango Counties it is very rare, but becomes again abundant in 

 French Creek in Venango and Crawford Counties, as far up as Le- 

 boeuf Creek in Erie County. It is absent from the whole Kiski- 

 minetas drainage and the upper Allegheny above Venango County. 



37. Quadrula cylindrica (Say). 



Cited in Harn's list from western Pennsylvania and in Rhoads' list 

 from the Ohio and Beaver. 



There is a dead shell in the Carnegie Museum from the Monon- 

 gahela at Charleroi, Washington County (Ehrmann Collection), and 

 the writer has found a dead specimen in the Ohio in Beaver County. 

 Living specimens have been found repeatedly in the Mahoning and 

 Shenango Rivers, and in Pymatuning Creek in Lawrence and Mercer 

 Counties, in the Allegheny in Armstrong County, and in French 

 Creek in Venango and Crawford Counties. 



38. Quadrula metanevra (Rafinesque). 



Not mentioned in the lists of Harn, Stupakoff, and Clapp. Reported 

 by Rhoads from the Ohio. 



It is restricted to the larger rivers, occurring in the Ohio in Beaver 

 County (formerly in Allegheny County), the Monongahela (Charle- 

 roi), and the Allegheny, Armstrong County. 



