The Crawfishes of Western Pennsylvania. 403 



This species has been reported hitherto only from two localities : 

 the type locality in the Genessee River at Rochester, New York 

 (Hagen), and from Westmoreland county, Pa. (Faxon). William- 

 son mentions C. propinquus and rusticus from the Allegheny, Monon- 

 gahela and Ohio Rivers in Allegheny county, but as the specimens in 

 the Carnegie Museum show, \\h propinquus represents young specimens 

 of C. obscurus, while his rusticus is founded upon full grown males 

 and females of the same species. 



C. obscurus is, aside from C. bartoni, the most abundant species in 

 western Pennsylvania, and belongs, generally speaking, to the drainage 

 of the three great rivers, Ohio, Allegheny and Monongahela. It is 

 very numerous in the Ohio in Beaver and Allegheny counties, and has 

 also been found in creeks running westward through the panhandle of 

 West Virginia to the Ohio, for instance in Harmons and Buffalo 

 Creeks in Washington county. It has been traced up the Allegheny 

 River from Allegheny county through Clarion, Venango, Warren 

 counties (specimens from Corydon are in the Academy in Philadel- 

 phia), then into New York state (Salamanca, Cattaraugus county, 

 specimens in the Philadelphia Academy), and back into Pennsylvania, 

 McKean county. Up the Monongahela River it has been traced to 

 the Cheat River at Cheat Haven, Fayette county, and up the Youghio- 

 gheny as far as Connelsville, Fayette county, and the Indian Creek at 

 Jones Mills, ^V''estmoreland county. In the Kiskiminetas and Cone- 

 maugh, it goes as far as Blairsville Intersection, Westmoreland county, 

 and up the Loyalhanna into Ligonier Valley. In the Beaver and 

 Shenango Rivers it goes to Crawford county, and in French Creek at 

 least as far as Union City, Erie county. Within the area thus out- 

 lined, it is found also in smaller streams up to a certain point, which 

 cannot be defined in a general way, till it is replaced by C. bartoni 

 occupying the rough and cooler waters near the source of each 

 stream. 



The presence of C. obscurus has been established in the following 

 counties : Greene, Fayette, Washington, Westmoreland, Beaver, Alle- 

 gheny, Butler, Clarion, Venango, Erie, Crawford, Warren, McKean ; 

 all these belong to the Ohio drainage. But there are a few additional 

 remarkable facts. (i) The upper Youghiogheny and Casselman 

 Rivers do not contain this species, and it is thus lacking in south- 

 eastern Fayette and in Somerset counties. This species goes up the 

 Youghiogheny as far as Connellsville, and probably a little beyond. 



