238 U.S. NATIONAL MUSEUM BULLETIN 271 



Type-species: Gammarus pugettensis Dana, 1853 (monotypy and 

 subsequent synonymy). See J. L. Barnard, 1954. 



Accessory flagellum more than 3-articulate; lower lip with small 

 or obsolete inner lobes; inner plates of maxillae both densely setose 

 medially; gnathopod 1 slightly larger than 2, palms bearing many 

 chisel-shaped spines; uropod 3 exceeding uropod 1, outer ramus long, 

 2-articulate (? rarely 1 -articulate) , inner ramus long or very short; 

 telson deeply cleft; urosome and occasionally metasome armed with 

 dorsal bundles of spines, except one species [type of Anisogammarus] 

 having a tooth on urosomite 2 instead of spines. Species: 18, boreal 

 Pacific, littoral and freshwater. Includes former marine members 

 of Echinogammarus. Possibly this genus divisible into 4 subgenera. 



Bathyceradocus Pirlot 



Bathyceradocus Pirlot, 1934 



Type-species: B. stephenseni Pirlot, 1934 (original designation). 



Accessory flagellum multiarticulate; lower lip lacking inner lobes; 

 inner plates of maxillae 1-2 densely setose medially; gnathopods 

 small, subchelate, slender; uropod 3 exceeding uropod 1, rami of me- 

 dium length, subequal, broadly lanceolate, outer 1-articulate; telson 

 deeply cleft; metasome and urosome toothed and carinate, urosome 

 with scattered dorsal spines; palp article 4 of maxilliped short, blunt, 

 apically setose (Metaceradocoides) . Species: 1, Indo-Pacific, bathyal- 

 abyssal (1,165-4,930 m). 



Casco Shoemaker 



Casco Shoemaker, 1930. 



Type-species: Cheirocratus bigelowi Blake, 1929 (original desig- 

 nation). 



Accessory flagellum 2-articulate; lower lip with inner lobes; inner 

 plates of maxillae 1-2 densely setose medially; gnathopod 1 essentially 

 simple, but dactyl large and folded back on article 6, gnathopod 2 

 slightly larger than 1 and shghtly subchelate; uropod 3 exceeding 

 uropod 1, rami subequal, long, lanceolate, outer 1-articulate; telson 

 deeply cleft; urosome with a tooth and scattered spines; antenna 1 

 reaching only to end of peduncle oj antenna 2 (Cheirocratella) ; antero- 

 ventral corner of head strongly produced. Species: 1, boreal W. Atlantic, 

 littoral. 



Ceradocoides NichoUs 



Ceradocoides NichoUs, 1938. 

 Type-species: C. chiltoni NichoUs, 1938 (original designation). 



