!88 Annals of the Carnegie Museum. 



collection, there is a collection made by G. A. Ehrmann in the Mo- 

 nongahela River at Charleroi, Washington County, acquired in 1897 ; 

 a collection made by Miss Vera White in Little Beaver Creek at 

 Cannelton, Beaver County, acquired in 1897 ; and a collection made 

 by H. H. Smith at the same locality in September, 1897. Besides 

 there are single species from various places collected by others, which 

 need not be mentioned here. 



The list is arranged according to Simpson's Synopsis (Proceedings 

 United States National Museum 22, 1900). In a final treatise on the 

 Unionidae of Pennsylvania, this system will be considerably changed. 

 The alterations introduced here relate chiefly to the nomenclature. 



A. Ohio River Drainage. 



1. Truncilla triquetra Rafinesque. 



Not reported by Harn, Stupakoff, and Clapp ; reported from the 

 Ohio and Beaver Rivers by Rhoads. 



Generally distributed in the Ohio, Beaver, and Allegheny drainages, 

 and going up into the smaller tributaries: Shenango River and Pyma- 

 tuning Creek in Mercer County ; French Creek in Venango and Craw- 

 ford Counties ; Conneaut Outlet in Crawford County ; Leboeuf Creek, 

 Erie County. It has not been recently found alive in the Ohio River 

 below Pittsburgh. It is rather abundant in the Allegheny River in 

 Armstrong County, but never found in the Monongahela drainage. 



2. Truncilla (Pilea) perplexa rangiana (Lea). 



Not report^ed previously. Rather abundant in the Allegheny River 

 from southern Armstrong County up through Venango and Forest into 

 Warren Counties (here also in Connewango Creek), and further in 

 French Creek in Venango and Crawford Counties. A single specimen 

 has been found in the. Shenango River in Lawrence County. 



3. Micromya fabalis (Lea). 



Reported by Harn from western Pennsylvania. Rhoads' Unio par- 

 vus from the Beaver at Wampum is probably this species. 



Found rather sparingly in the Beaver and Allegheny drainages ; in 

 the Mahoning River in Lawrence County ; in the Shenango River and 

 Pymatuning Creek in Mercer County ; in Crooked Creek in Armstrong 

 County; French Creek in Venango and Crawford Counties; in the 

 upper Allegheny in Venango County, as far up as Connewango Creek 

 in Warren County. It is nowhere abundant, and is missing in the Mo- 

 nongahela drainage. 



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