400 Annals of the Carnegie Museum. 



ern Pennsylvania, whence it has never been reported before, although 

 it is known from New Jersey (Trenton) ; the writer discovered it at 

 Ridley Park and Marcus Hook in Delaware county. 



The distribution of this species is quite puzzling; the curious fact 

 that it is found both east and west of the Allegheny Mountains, but 

 that it is clearly missing in the high plateau between Chestnut Ridge 

 and Allegheny Mountains (at least in Pennsylvania), and that it is 

 also absent from the region lying to the east of the main mountain 

 chain, and does not appear till we reach the lowlands on the Delaware 

 River, is not easily explained, unless there is a connection across the 

 mountains somewhere south of the southern state line. It has been 

 reported by Faxon from Deer Park, Garrett county, Maryland, but 

 this record needs confirmation, since we rather ought to expect here 

 another species, C. caroliniis. A closer investigation of western 

 Maryland, and eastern and northern West Virginia will probably throw 

 light upon this question. 



Cainbariis diogenes is the best known of the "chimney builders." 

 It prefers the bottom lands along the large rivers, but goes quite 

 regularly up the valleys, where it often comes into contact with C. 

 viouongalensis or C. caroliniis. Generally, if C. diogenes is found at a 

 given locality, C. mononga/ensis or caroliniis, if found associated with 

 it, are less abundant, but become more frequent, and finally are exclu- 

 sively found, if we go higher up on the hillsides. The holes of C. 

 diogenes are decidedly less complex than those of the other two spe- 

 cies ; very often they consist only of a single shaft, generally going 

 down in a slanting direction, that ends in a pocket ; rarely there are 

 lateral branches. 



Western specimens of C. diogenes attain a very considerable size 

 (4.5 in. =: 115 mm., Hagen). The largest individuals from Penn- 

 sylvania represented in the Carnegie Museum are : a male of the first 

 form from Nine Mile Run, Pittsburgh, 92 mm., and a female from 

 Dunbar, Fayette county, 95 mm. 



5. Cambarus propinquus Girard. The Lake Erie Crawfish. 



This species is easily recognized when adult males of the first form 

 and adult females are at hand. Young and undeveloped specimens 

 are rather hard to distinguish from C. obscnrus. It differs from all the 

 preceding species by the characters of the fourth group, the form of 

 the male appendages, and further, by the rostrum, which possesses a 



