336 ORTMANN— THE ALLEGHENIAN DIVIDE. [April 1 8, 



B. Crayfishes of the Atlantic Side. 



Cambarus blandingi (Harl.). This species has not been treated 

 in my report on the Pennsylvanian crayfishes, but I have discovered 

 subsequently that it is present in great numbers in the ditches of the 

 Delaware meadows at League Island, Philadelphia. Its distribution 

 is from New Jersey to Georgia, and in a slightly different form (var. 

 acutus Gir.) it extends westward over the Gulf plain to Texas, and 

 northward into the interior basin. The existence of related species 

 chiefly upon the Gulf plain (Ortmann, 1905, p. 105) indicates that the 

 center of this species is in the southeastern United States, and there 

 is no question that it reached our section (from Virginia northward) 

 by migration coming from the south. Thus it clearly belongs into 

 the same group to which those Najades belong, for which we have 

 located the center of dispersal in the southern parts of the Atlantic 

 slope. 



Cambarus limosus (Raf.) A species confined primarily to the 

 lowlands and Piedmont region from New Jersey to Virginia, but 

 which has gone up, in the Susquehanna and Potomac, into the moun- 

 tains, possibly only secondarily. The facts of the distribution have 

 been compiled in my former paper (1906, pp. 425 ff.), and the con- 

 clusion was reached (p. 432) that this is a form belonging to tlie 

 northern section of the Atlantic slope, and that its connection with 

 the western forms allied to it is around the northern end of the 

 Appalachians. Thus it clearly falls into the same category with 

 certain Najades mentioned above. 



Cambarus obscurus Hag. This western species exists in the 

 upper Potomac drainage. I have previously (1906) considered this 

 as an accidental introduction, and more recently (1912&, pp. 51-54) 

 I have parallelized this case with that of Lampsilis ventricosa cohon- 

 goronta, as due to artificial transplantation. Thus this is not an 

 original feature of the Potomac drainage, and should be disregarded. 



Cambarus acuminatus Fax. A species, known hitherto from the 

 Atlantic drainage only in North and South Carolina, and also re- 

 ported from French Broad River in North Carolina, tributary to the 

 Tennessee. On the Atlantic side, however, this species extends 

 farther north, and I have found it in Mason Creek, at Salem, and 



