The Crawfishes of Western Pennsylvania. 391 



and it is, in this region, the only species that inhabits the rivers, C. 

 obsciints, the typical river-species, being absent here. 



Cambarus bartoni goes far up into the mountains : the highest 

 elevation at which it was collected is at Sand Patch, Somerset county, 

 about 2,300 feet above sea level ; here it was abundant in little moun- 

 tain streams above the western entrance of the B. & O. R. R. tunnel. 



This species attains, in the southwestern section of the state, a con- 

 siderable size. Hagen (1870) gives 3.6 in. = 91 mm. as maximum 

 size ; according to the writer's observations, specimens from eastern 

 Pennsylvania rarely grow beyond 60 mm. (largest male in Carnegie 

 Museum, from near Valley Forge, Chester county, 61.5 mm.; largest 

 female, from Wissahickon, Philadelphia county, 64 mm.), while in 

 western Pennsylvania much larger specimens are not rarely met with ; 

 the largest male of the first form in the Carnegie Museum collections 

 is from North Versailles township, Allegheny county (opposite 

 Stewart, Westmoreland county), and measures 83.5 mm.; the largest 

 female is from Hill, Westmoreland county (opposite Leechburg, 

 Armstrong county), and measures 89 mm. (A male of the first form 

 from Cheat River, West Virginia, is 92 mm.) 



The color of C. bartoni is more or less brownish olive, in young 

 specimens often rather greenish, in old ones frequently with coppery 

 or bronze hue. The shade of color is quite variable, but generally 

 it is more brownish than in other species. Rarely there are individ- 

 uals of a bluish hue, but this blue is never bright and brilliant (as in 

 C. monongalensis^ but rather dull, like blue slate or clay. Often the 

 shell is rendered more or less blackish by the deposit of a mud incrusta- 

 tion upon it. 



\a. Cambarus bartoni robustus (Girard). 

 As has been done by most writers, I regard this form as a variety of 

 C. bartoni. It differs chiefly in the shape of the rostrum, which is 

 more elongate and narrower than in the typical form. Hagen, who 

 mentions this form as a good species, gives the following additional 

 characters : the large chela has a distinct impression near the outer 

 margin of the hand, both above and below ; the inner margin of the 

 hand has a double row of tubercles ; and the carapace has a spine on 

 each side behind the cervical furrow. These characters, however, 

 are not always distinctly developed, and, among the specimens from 

 Allegheny county, the lateral spine is generally wanting, although we 



