I9I3-] ORTMANN— THE ALLEGHENIAN DIVIDE. 33.'* 



is the only Campeloma present, and it should be emphasized that in 

 the upper Kanawha drainage, in Greenbrier River, not this species, 

 but C. decisum is found. 



C '. ruf 'um and ponderosum have no representatives on the Atlantic 

 side, and clearly belong to the fauna of the upper Ohio River, 

 although they probably belong to different parts of it. 



IV. DECAPOD CRUSTACEANS: THE CRAYFISHES OF THE 



GENUS CAMBARUS. 



The conditions presented by the distribution of the crayfishes 

 have been discussed by the writer with regard to the state of Penn- 

 sylvania (Ortmann, 1906). These studies have been continued to- 

 ward the south, and most of the facts given here for Virginia and 

 West Virginia are new and add considerably to our previous knowl- 

 edge. Of course, a certain ecological group is to be disregarded 

 here, the burrowing crayfishes, for they do not live in open water, 

 rivers or creeks, and do not depend in their distribution on drainage 

 systems (Cambarus caroIinus'Ev^C.monongalensis Ortm., C. di ogenes 



Gir.). 



A. The following river and creek forms are found on the west- 

 ern side of the mountains. 



Cambarus obscurus Hag. This species belongs to the upper Ohio 

 system, from Moundsville, W. Va., in the Ohio, and from Fishing 

 and Fish Creek upward. But it should be noted that subsequent 

 investigations have shown that it goes a little farther down in the 

 Ohio proper, for it is in the river at St. Mary's, Pleasants Co., W. 

 Va. In the Allegheny River this species goes up to the headwaters 

 (Coudersport, Potter Co., Pa.), and also in the tributaries (Red 

 Bank, Mahoning, Crooked), except in the Kiskiminetas-Conemaugh, 

 where it goes only to the mouth of the canyon at Blairsville, while 

 it goes up into the upper Loyalhanna in Westmoreland Co. Thus 

 the Conemaugh resembles the conditions seen in the more southern 

 mountain tributaries of the Monongahela. In the latter this species 

 goes only to the lower end of the canyons, and is not found in the 

 upper parts (Youghiogheny, Cheat, Tygart), while in the plateau 

 stream, West Fork River, it is found nearly to the sources (Weston, 

 Lewis Co., W. Va.). 



