The Crawfishes of Western Pennsylvania. 389 



gheny Mountains between Cambria and Somerset counties in the west, 

 and Blair and Bedford counties in the east. 



Within the region thus defined we have the following six species of 

 Cambariis : (i) Cambarus harfoni {Y .'), (2) Cavibanis carolinus Yrc., 

 (3) Cambarus monougalensis wo\. spec, (4) Ca inbarus diogc?ies G\r., 

 (5) Cambarus propiiujiius Q\x., (6) Ca7nbarus obsciiriis 'Rag. 



\\\t\\ the exception of Camba?-i/s nionongalensis, all these species 

 are rather well known, although two of them ( C: carolinus and obscui'us^ 

 were considered as quite rare. To facilitate the identification of these 

 species, the following key is offered. 



I. Species belonging to the third group of the genus (type : C. hartoni'). Ischium 



(third segment) of third pair of legs of male hooked. First pair of abdominal 

 appendages of male terminated by two thick, strongly recurved teeth. In all 

 Pennsylvania species the rostrum has no lateral spines, and the lateral parts of 

 the carapace, behind the cervical furrow, possess generally no spines (with oc- 

 casional exceptions in C. barioiti robiisttis^. 



A. Areola wide. Form of carapace depressed. Color (in life) brownish or 



greenish olive. (Mountain brook species. ) C. bartoni. 



B. Areola narrow or obliterated. Form of carapace compressed. (Burrowing 



species. ) 



1. Areola narrovsf. Color in life remarkably bright, of tints unusual among 



crawfishes. Abdomen distinctly shorter than carapace. 



a. Color bright red (chiefly so on chelo? and anterior part of carapace). Res 



trum broad and short. ( Mountain species. ) C. CAROLINUS. 



b. Color bright blue (chiefly so on chelae and anterior part of carapace). Ros- 



trum narrower, short. (Hill species. ) C. monongalensis. 



2. Areola obliterated in the middle. Color of the usual tints in crawfishes : 



greenish or brownish olive. Abdomen about as long as the carapace. 

 Rostrum rather long and narrow. (Bottom land species. ) 



C. DIOGENES. 



II. Species belonging to the fourth group of the genus (type : C. affinis). Ischium 



of third pair of legs of male hooked. First pair of abdominal appendages of 

 male terminated by two slender, styliform, nearly straight teeth. In the 

 Pennsylvanian species, the rostrum has a lateral spine on each side, the carapace 

 has a spine on each side behind the cervical furrow, and the areola is wide. 

 Color green or brownish olive, with a reddish spot on each side of the anterior 

 margin of carapace, below eye. (River and lake species.) 



A. Rostrum with median keel. First pair of abdominal appendages of male at 



base of terminal teeth without prominent angle. Annulus ventralisof female 

 flat. C. PROPINQUUS. 



B. Rostrum without median keel. First pair of abdominal appendages of male 



at base of terminal teeth with a distinct, prominent angle on the anterior 

 margin. Annulus of female with two tubercles in anterior part. 



C. OBSCURUS. 



