58 A REVISION OF THE ASTACID^E. 



long, slender antennae, and the areola is not reduced to a line in the middle, 

 as it is in larger specimens. 



C. gracilis has much the general habit of C. Diogenes of the same region, 

 but the male appendages are formed 'after the fashion of the C. Blandiiigii 

 group. The annulus ventralis of the female is also quite different from that 

 of C. Diogenes. Apart from the sexual characters, it is distinguished from 

 C. Diogenes by the very prominent single row of teeth on the inner border 1 

 of the hand, the narrower cephalothorax, etc. It agrees very closely with 

 the male specimen from Charleston, referred by me to C. Carolinus Erichs. 

 (p. 54), described by Hagen on page 86, under the name of C. advena. The 

 Western species differs, however, in the rostrum, which is more sharply angu- 

 lated at the base of the acumen, the fore border of the carapace is angulated, 

 the carpus and meros are more spiny, the rib on the internal lamina of 

 the swimmeret terminates in a spine inside the margin. The male appendages 

 are like those of G. Carolinus. It differs from C. advena in the male appen- 

 dages and shape of rostrum. The annulus ventralis of the female is much 

 like that of C. advena, but in that species the anterior tubercles are not 

 sharply multi-denticulate, as in G. gracilis. The female of C. Carolinus has 

 probably not yet been made known. (See p. 55.) The female specimen 

 (M. C. Z. Cat., No. 3453) mentioned by Hagen, page 82, as an abnormal 

 specimen of C. obesus, is C. gracilis. 



According to Dr. P. R. Hoy, C. gracilis burrows in the clay in the prairies 

 near Racine, Wis. ; and Professor Forbes states that it is very common along 

 water-courses, in early spring, in the neighborhood of Normal, 111. Mr. H. 

 Carman informs me that, among hundreds examined from such localities, he 

 has not found a dozen males. Other localities are Lawn Ridge, 111., Athens, 

 111., and Davenport, la. There is a type specimen, male form I., received 

 from Professor Bundy, in the Museum of Comparative Zoology. 



