26 A REVISION OF THE ASTACID^. 



4. Cambarus Clarkii. 



Cambarus Clarkii, GiUAED, Proc. Acad. N;it. Sci. I'liilad., VI. 91, 1852. 



Cambarus Clarkii, H.\gen, 111. Cat. Mus. Comp. Zool., No. III. p. 39, PI. I. figs. 7-10, 99, 100, PI. II. figs. 



133, 134, PI. HI. fig. 142, PI. IV. (this figure is copied ou a reduced scale iu Huxley's " CrajCsli," 



p. 248, 1880), 1870. 

 Cambarus Clarkii, Faxon, Proc. Amor. Acail. Arts and Sci., XX. 136, 1884. 



Known Localities. — Texas : between San Antonio and El Paso del Norte 

 (Girard); San Antonio; Clear Creek, Waller Co. (Coll. U. S. Nat. Mas.). 

 Louisiana: New Orleans; Tangipahoa River (Coll. U. S. Nat. Mus.). Mis- 

 sissippi: Ocean Spriug.s, Jackson Co. (Coll. U. S. Nat. Mus.). Alabama: 

 Mobile. Florida: Pensacola (Coll. U. S. Nat. Mus.) ; three miles below Horse 

 Landing, St. John's River. Ohio: Olmsted [?]. 



Girard's specimens were collected between San Antonio, Texas, and El 

 Paso del Norte, by John H. Clark, of the U. S. Mexican Boundary Commis- 

 sion. The original description of the species is hardly sufficient for determi- 

 nation, but fortunately Dr. Hagen was able to identify the species by an 

 examination of Girard's types, which were probably lost in the great fire 

 at Chicago, whither they were sent to Dr. Stimpson. A full description 

 of C. Clarkii is given on page 39 of Hagen's Monograph. 



In specimens collected by Edward Palmer at San Antonio, Texas, tlie 

 carajiace is smoother than in the form commonly received from New Orleans 

 and Mobile, with more prominent lateral and postorbital spines. The ros- 

 trum tapers much less than in the form from forther east, the sides being 

 more nearly parallel. The areola, moreover, is not entirely obliterated in 

 the middle, but forms a linear area about as wide as in C. iroglodijics. The 

 male sexual appendages do not differ from those of the Louisiana speci- 

 mens. This is probably the form described by Girard. 



In this connection it is interesting to note that in young individuals of 

 this species eight millimeters long, taken from beneath the abdomen of a 

 female from New Orleans, the areola is proportionally even wider than in the 

 San Antonio specimens. 



In a male, form II., GO mm. long, collected by J. A. Allen in St. John's 

 River, Fla., the areola is like that described in the San Antonio specimen.s, 

 and the distal margin of the proximal segment of the telson is armed Avith 

 three or four spines on each side. The carapace is smooth. 



A female specimen, 92 ram. long, in the Academy of Natural Sciences of 

 Philadelphia (No. 654), fi'om the Smithsonian Institution, without locality, 



