ASTACID^. 65 



Cat. No. 194, Lake Superior, L. Agassiz. Male Form I. and II. Fern. 

 Spec. 12* 



Cat. No. 203, Lake Superior, L. Agassiz. Male Form II. Fern. 

 Spec. 6. 



Cat. No. 1828, Lake Winnipeg, British America, Mr. S. H. Scudder. 

 Male. Fern. Spec. 12* 



Cat. No. 1829, Red River, British America, Mr. S. H. Scudder. Male. 

 Fem. Spec. 12* 



Cat. No. 1830, Saskatchavan River, British America, Mr. S. H. Scud- 

 der. Male. Fem. Spec. 4. 



Cat. No. 196, Quincy, 111., Dr. Watson. Male. Fem. Spec. 12.* 



Yar. A. 



Cat. No. 1831, Osage River, Dr. Stolley. Male Form II. Fem. 

 Spec. 12* 



Cat. No. 1832, Osage River, Dr. Stolley. Male Form II. Fem. 

 Spec. 12* 



Cat. No. 192, Osage River, Dr. Stolley. Male Form I. Spec. 1. 



Cat. No. 171, Burlington, Iowa. Male Form I. Fem. Spec. 3. 



Cat. No. 200, Texas, Dr. Stolley. Male Form I. Fem. Spec. 12.* 



Cat. No. 207, Texas, Dr. Stolley. Male Form I. Fem. Spec. 4. 



Cat, No. 1833, Davenport, Iowa. Male Form I. Fem. Spec. 3. 



Dry Spec, Lake George, L. Agassiz. Male. Spec. 1. 



17. Cambarus placidus Hag en. 



j^^ 



Figures on PI. I. and III. 

 First abdominal legs of the male : 



first form, fig. 7G in front ; fig. 77 outside. 



not articulated second form, fig. 78 in front; fig. 79 outside. 

 Antennal lamina, fig. 158, a ; epistoma, b ; spine of the second joint of the exterior antenna, c. 



This species is intermediate between C. virilis and C. juvenilis. It 

 lives in the same localities, — Texas, Tennessee, and Quincy, Illinois. 

 In its general form, more cylindrical thorax, smaller and more deeply 

 sulcated rostrum, with the margins more thickened, it resembles C. juve- 

 nilis ; the abdominal legs of the male (Forma I. and II.) are very sim- 

 ilar to those of C. virilis, though in one male the posterior hook is 

 slightly evident ; nevertheless, the forehands are very dissimilar, more 

 slender, much longer, not so much punctated, especially on the fingers, 

 which are flattened ; the inner margin of the hands is very little tuber- 

 culated ; the fingers are more separated at the base, while the external 

 one is not barbated ; a few females from Tennessee have little hairs, 

 and are scarcely tuberculatecl at the inner margin, though sometimes 

 they are much elongated ; the carpus is bispinose beneath, the spines 

 often being very obtuse, especially the interior ones ; the biseriated 



