The Crawfishes of Western Pennsylvania. 399 



two last named. It is more or less of the usual pattern among craw- 

 fishes, namely brownish or greenish olive. In well-developed, adult 

 individuals, there is generally (in western Pennsylvania) a beautiful 

 verdigris-green present on the base of the fingers, which, together 

 with the orange-red finger-tips and the reddish margin of the rostrum, 

 renders the coloration of such specimens rather vivid and attractive. 

 But there are great variations in color : a specimen found in the fall 

 of 1903 in Fern Hollow, Pittsburgh, in a puddle of yellowish-brown 

 mud had assumed entirely this yellowish-brown mud color. A re- 

 markable variety was found at Dunbar, Fayette county : a large male of 

 a prevailing red color, similar to C. caroliiiiis, but less brilliant. This 

 apparently is to be regarded as a case of albinism ; although found as- 

 sociated with C. caroUniis, this specimen possesses all the typical mor- 

 phological characters of C. diogenes and moreover, typically colored 

 individuals were abundant at the same place. 



C. diogenes is a well-known species occupying a wide range in the 

 United States. In Pennsylvania it was recorded hitherto only from 

 Derry, Westmoreland county (Faxon, 1885), and from Pittsburgh, 

 Allegheny county (Williamson). The investigations of the writer, 

 and additional material in the Carnegie Museum, collected by others, 

 have shown that it is quite abundant in the southwestern section of 

 the state. In Allegheny county it is common, being found chiefly in 

 the bottom lands along the rivers, but it also goes up to the elevation 

 of about 900 feet (200 feet above the rivers), apparently following 

 upwards the valleys and ravines that empty into the large rivers. In 

 Westmoreland county it is abundant at Derry (already recorded by 

 Faxon), and has also been taken at Blairsville Intersection. In 

 Washington county it has been found at Francis Mine (near Bur- 

 gettstown) ; in Greene county, near Waynesburg ; in Fayette county, 

 near Smithfield and Dunbar, at the foot of the Chestnut Ridge. 

 East of Chestnut Ridge, in I'ayette, Somerset and Westmoreland 

 counties, it is positively wanting: careful search for it in Ligonier 

 Valley and the drainage of the upper Youghiogheny and Casselman 

 Rivers has been unsuccessful. Its northern boundary is at present not 

 well known : the most northern point is just below Bakerstown Sta- 

 tion, Richland township, Allegheny county, but it may pass into 

 Butler and Armstrong counties, which have not yet been examined 

 satisfactorily. 



It may be mentioned here that C. diogenes is also present in east- 



