172 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



the right chela and right legs, anc] probably the last left leg, are in 

 process of regeneration. 



Measurements. Female (para type), length of carapace 5.8. width 

 of same 8.2 mm. Male (49247), length of carapace 4.6, width of 

 same 6.2 'mm. 



Range. Departure Bay. British Columbia, to Ensenada, Lower 

 California. 



Specimens examined. 



Departure Bay, British Columbia; George W. Taylor; 1 female 

 (39130). 



Friday Harbor, Washington; in Mya arenaria; July 1, 1916; 

 Evelyn D. Way; 1 male, 1 female (49951). 



Puget Sound; Aug., 1908; 3 males, 3 females, ovig. (Stanford 

 Univ.). 



Puget Sound, near Tacoma, Washington ; 1907 ; 2 males, 2 females 

 ( 1 ovig. ) , ( Stanford Univ. ) . 



Oyster Bay, Washington, from stomach of Bufflehead (Chari- 

 tonetta albeola); Dec. 4, 1914; 1 female (Biol. Survey Coll.. U. S. 

 Dept. of Agr.). 



Middle San Francisco Bay ; 7-4 fathoms ; large and small angular 

 rock fragments; temp. 12.01 C. ; Apr. 16, 1912; station 5775<z; 

 steamer Albatross; 1 male (49247). 



Ensenada, Lower California; C. R. Orcutt; 3 females (holotype 

 and paratypes) and fragment of male (17497). 



Genus OPISTHOPUS Rathbun. 



Opisthopus RATHBUN, Proc. U. S. Nat. Mus., vol. 16, 1893, p. 251; type, 0. 

 transversus Rathbun. 



Carapace subquadrilateral, a little wider than long, firm, harder 

 in male than in female, smooth; regions not defined; antero-lateral 

 margins arcuate; front rounding down toward the epistome. Outer 

 maxillipeds with ischium well developed and well defined, but partly 

 fused with the merus; merus wide, palpus 3- jointed, the last joint 

 articulated near the proximal end of the inner side of the penulti- 

 mate joint. Ambulatory legs similar and differing little in size, 

 second longest. 



Perhaps should be united with Pinnaxodes. 



Known only from the typical species. 



