of the Pacific Shores of North America. 493 



Hab. California. My specimens were purchased in the 

 market of San Francisco. 

 Mus. Smithsonian. 



ASTACUS LENIUSCULUS. Dana. 



Astacus leniusculus, Dana; U. S. Exploring Expedition, Crust, i. 524. 



PL XXXIII. f. 1. 



May be recognized by its well-developed thoracic spines, 

 and light color. 



Hab. Columbia River, (Expl. Exped. ;) Puget Sound, 

 (Expl. Exped., and Dr. Suckley.) 



Mus. Expl. Exped. ; Smithsonian. 



ASTACUS TROWBRIDGII. Stimpson. 

 Astacus Trowbridgii, Stimpson ; Proc. Bost. Soc. Nat. Hist. vi. 87. 



This large species has a general resemblance to A. lenius- 

 culus. It differs from that species in having much less 

 prominent thoracic spines, the posterior pair of which is 

 here but little developed, even in adult specimens. The 

 rostrum is also somewhat shorter and broader than in the 

 preceding species, with smooth, nearly parallel sides ; ter- 

 minal tooth of moderate length ; antero-lateral teeth suffi- 

 ciently prominent. Dorsal area broader than in A. Gambelii, 

 but narrower than in A. leniusculus. Hands large, robust, 

 equal in size ; surface rough ; fingers spinulose. A promi- 

 nent sharp spine on the superior edge of the brachium near 

 its extremity. 



This species is of a reddish-olive color in preserved speci- 

 mens, probably much darker in life. The color of the chelae 

 is much darker than that of the body. The dimensions of 

 a male specimen are as follows : — 



Length of body 4.80 inches 



Breadth " 1.30 " 



Length of rostrum .50 '• 



" terminal tooth of rostrum . . . . .18 " 



" hand 2.60 " 



Breadth of "... ... 1.15 " 



