ASTACIDiE. 69 



before the base. The rostrum is carinated as in the tvpe. The iden- 

 tity is rendered much more prol)able, since I have seen from the same 

 locality male and female types, both full grown and young, and the 

 two forms of the male. In one male, nearly fidl grown, the rostrum 

 is scarcely carinated at all. 



Two males, Forma I., from Kochester, N. Y., were mixed Avith C. 

 obsciinis. 



The very young and small specimens much resemble those of C af- 

 fiiik. The rostrum is more acute, the thorns at the base of the acumen 

 long and acute, the extei'ior nuirgin of the antenna! lamina sinuated, 

 but the acumen is always a little carinated, and the hands are broader 

 and shorter. 



C. propbtquus Gir. differs from C. ririlis in having its rostrum carinated 

 and narrower, with the acumen longer than broad ; the cephalothoracic 

 carina} more distant from the margin ; the lamina of the antenna) nai'- 

 rower, more acute ; the maxillary legs without hairs externally ; the 

 carpus below with only one anterior spine, the brachium externally 

 smooth ; the inner margin of the chela straight ; the areola broader, 

 but not so much enlarged behind ; the lamina media of the postalxlo- 

 men more rounded. The angle of the cephalothoracic margin behind 

 the eyes is almost obliterated. 



Cat. No. 202, Lake Superior, L. Agassiz. Male Form II. Spec. 12.* 



Cat. No. 1835, Lake Superior, L. Agassiz. Male Form I. Spec. 12.* 



Cat. No. 206, Lake Superior, L. Agassiz. Fem. Spec. 12.* 



Cat. No. 1836, Ugle County, 111. Male. Fem. Spec. 6. 



Cat. No. 1837, locality unknown. Male Form II., first pair of ab- 

 dommal legs not articulated. Spec. 3. 



Cat. No. 268, Delphi, Indiana, Mr. F. C. Hill. Male. Fem. Spec. 

 12.* 



Cat. No. 205, Niagara, L. Agassiz. Male. Fem. Spec. 12.* 



Cat. No. 247, Niagara, L. Agassiz. Fem. Spec. 1. 



Cat. No. 185, Niagara, L. Agassiz. Male. Fem. Spec. 12.* 



Cat. No. 1838, Rochester, N. Y., Professor C. Dewey. Male. Spec. 2. 



Cat. No. 1839, Lake Oneida. Male. Spec. 3. 



Dry Spec, Niagara, L. Agassiz. Male. Fem. Spec. 2~ 



20. Cambarus obscurus Hagen. 



Figures on PI. I. and III. 

 First abdominal legs of the male. 



first form, fig. 72 in front; fig. 73 outside. 



second form, fig. 74 in front ; fig. 75 outside. 

 Antennal lamina, fig. 1.54, a; epistoma, 6 ; spine of the second joint of the exterior antenna, c. 



Male. This species is very similar to C. projiiiiquus, and I have seen 

 the males from the same locality mixed in the same bottle. But hav- 



