The Crawfishes of Western Pennsylvania. 397 



formed by .the northwestern slope of the Chestnut Ridge, and C. 

 monongalensis is found distributed on the hills lying on the west and 

 northwest of this ridge. The range of this species comprises the 

 northwestern part of Fayette county, Washington county and parts of 

 Westmoreland, Allegheny and Beaver counties. It has not yet been 

 found in Greene county, but is undoubtedly also present there. In 

 Beaver and Allegheny counties, the valley of the large rivers, Ohio 

 and Allegheny, apparently forms the northern boundary of this spe- 

 cies : in fact, it has been found north of these rivers only at a single 

 locality near Squaw Run, Allegheny county (by Dr. D. A. Atkinson), 

 while it is very abundant on the hills south of these rivers. In Alle- 

 gheny county, south of the Allegheny River, whence it has been re- 

 ported by Williamson under the name of C. dubius, it is present every- 

 where, in swampy places on the hills, generally at an elevation from 

 900 to 1,100 feet, rarely going farther down (in Schenley Park and 

 Fern Hollow, within the city line of Pittsburgh, it descends to a little 

 below 800 feet). It is especially abundant on the hills east of Wil- 

 kinsburg and Edgewood Park, and specimens from the latter locality 

 (head of Gordon's Valley, Edgewood Park, elevation 1,000-1,100 

 feet) have been taken as the types for the above description. The 

 oldest specimen in the Carnegie Museum collections is from Moon 

 township, Allegheny county, and was collected by A. T. Shafer in 

 1898 (Cat. no. 74.20), 



In Westmoreland county this species has been found at Braeburn, on 

 hills above the Allegheny River, at Jeanette, and it reaches the valley 

 of the Kiskiminetas at Hill (opposite Leechburg, Armstrong county). 

 In Beaver county it is abundant on Doctor Heights, Monaca, south of 

 the Ohio. 



In Washington county it has been found at Monongahela City, at 

 Francis Mine (near Burgettstown), and near Taylorstown. 



In Fayette county it is present near Smithfield and Cheat Heven. 



Thus it has been traced from the southern state line in Fayette 

 county (Cheat Haven) to the northernmost point of the Ohio River 

 (Monaca), and almost to the point of the triangle formed by the Kiskim- 

 inetas and x'Mlegheny Rivers (Hill and Braeburn); and from the foot of 

 the Chestnut Ridge to near the western state line in Washington county 

 (Taylorstown and Francis Mine), and very likely occupies all of the 

 state that is included between the Chestnut Ridge to the east, the 

 Ohio-Allegheny Rivers to the north, and the southern and western 



