192 Annals of the Carnegie Museum. 



13. Proptera gracilis (Barnes). 



Not in Harn's list. Recorded by Clapp from Allegheny County, 

 and by Rhoads from the Ohio River. 



Abundant in the Ohio below Pittsburgh ; rare in the Allegheny in 

 southern Armstrong County. Formerly in the Monongahela at Char- 

 leroi, Washington County (Ehrmann Collection). Nowhere else. 



14. Obovaria retusa (Lamarck). 



Not reported previously from the state. A single live specimen 

 (gravid female) was found by the writer in the Ohio at Industry, 

 Beaver County. Subsequently a well preserved dead shell of a male 

 was found at the same place. 



15. Obovaria circulus (Lea). 



Lea records this species from the Monongahela at Pittsburgh. It is 

 reported by Harn from western Pennsylvania, and by Rhoads as 

 U. lens from the Ohio and Beaver. 



The writer has seen many dead shells from the Ohio in Allegheny 

 County. One living specimen, taken August i, 1906, was the last 

 livng Unionid found in the Ohio in Allegheny County. There are 

 specimens taken from the Monongahela at Charleroi, Washington 

 County, in the Ehrmann Collection. It is found living in the Mahon- 

 ing and Shenango Rivers and in Pymatuning Creek, Lawrence and 

 Mercer Counties. It occurs also in Crooked Creek in Armstrong and 

 Indiana Counties. It is now rather scarce. 



In the Ohio, the form circulus prevails, while in the smaller creeks 

 it generally takes the more compressed shape of O. lens (Lea) ; but 

 all manner of transitional variations between the two forms occur. 

 O. circulus and lens are not the male and female, as Sterki believes. 



16. Obovaria (Pseudoon) ellipsis (Lea). 



Recorded by Stupakoff from Allegheny County, but in no other list. 

 The writer found two specimens in the Ohio at Industry, Beaver 

 County. 



17. Plagiola securis (Lea). 



Reported in Harn's list from western Pennsylvania; in Clapp's list 

 from Allegheny County, in Rhoads' list from the Ohio. 



Rather abundant in the Ohio in Beaver County ; formerly occurred 

 in the Monongahela at Charleroi, Washington County (Ehrmann Col- 

 lection). Very rare in the Allegheny in southern Armstrong County. 

 Nowhere else. 



18. Plagiola (Amygdalonajas) elegans (Lea). 



