ORTMANN : THE CRAWFISHES OF THE STATE OF PENNSYLVANIA 457 



becomes rather probable. This is in keeping with tlie morphological cliaraeters, as 

 compared with C. cUogenes, for the latter, as we shall see below, is very likely also 

 preglacial. 



We have no evidence as to the Preglacial history of (: mononfjalensis. It may. 

 howevei-, be said, tliat it must have come from the original home of the subgenus 

 Badonius in the southern Appalachians. How for north it extended in Preglacial 

 times we do not know, but the advancing ice cannot have driven it back very far. 

 This is very probable because it is a form decidedly partial to cold water. With 

 reference to its Glacial-Postglacial migration it belongs to the northeastern biota and 

 the second wave of Adams ; but its advance was apparently checked at an early date 

 by the Ohio-Allegheny River. 



It will Ije remembered that with reference to C. carolinus another view has Vjeen 

 expressed (p. 453). In the case of that species we do not possess any facts which 

 enable us to fix its time of immigration into Pennsylvania with the same proba- 

 bility as in the case of C. monongalensis. The present extension of the range of C. 

 carolinus in the southern mountains classes it rather with the southeaster)! biota. On 

 the other hand, we know nothing about the southern range of C. rnonongaJensis, and 

 thus it is at present impossible to properly compare these two species. Their close 

 affinity, however, and the identity of the ecological conditions under which they 

 are found (aside from the difference in altitude) render it rather jjrobable that the 

 parallelism observed between them in some respects may reveal itself also in others. 



7. Cambaras diogenes. 

 a. Summary of facts. (See pp. 405-407.) 



Aside from a narrow strip along the Delaware River, in Delaware, Philadelphia, 

 and Bucks Counties in eastern Pennsylvania, this species covers a large area in 

 southwestern Peimsylvania, namely all the region occupied by C. mouoiigaleyusis, 

 ami. ill addition, a belt of a certain width to the north of it (see PI. XLIII). Here 

 the eastern boundary is formed, as in the case of ('. monoitgaleiusis, by the < "hestnut 

 Ridge, but it is continued beyond the Loyalhanna River, extending into Indiana 

 County, and then it follows the divide between the Sus(|uehanna and Allegheny 

 drainages as far north as the southern extremity of Jellei-son County. From this 

 region the boundary runs in a westerly direction. 



In Jefferson County I found this species at Punxsutawney, ami I have seen 

 chimneys rather abundantly to the east of this place, when riding on the P>uHalo, 

 Rochester, and Pittsburgh Railroad, about as far as IJig Run, Jederson County. But 



