350 U.S. NATIONAL MUSEUM BULLETIN 271 



Mesocyphocaris Birstein and Vinogradov 



Mesocyphocaris Birstein and Vinogradov, 1960. 



Type-species: M. longicaudatus Birstein and Vinogradov, 1960 

 (original designation) . 



Accessory flagellum 1-articulate; head somewhat deformed; man- 

 dible lacking molar, palp attached medially on mandibular body; 

 gnathopod 1 simple, articles 5 and 6 subequal; coxae 1 and 2 much 

 smaller than coxae 3 and 4 and probably partially hidden by coxa 3; 

 pereopods 1-4 prehensile; uropod 3 elongate, outer ramus 2-articulate, 

 inner very short and scale-like; telson short, cleft one third its length. 

 Species: 1, Pacific, abyssopelagic. 



Metacyclocaris Birstein and Vinogradov 



Metacyclocaris Birstein and Vinogradov, 1955. 



Type-species: M. polycheles Birstein and Vinogradov, 1955 (orig- 

 inal designation). 



Mandible lacking molar, palp attached rather distally; gnathopod 

 1 simple, article 5 longer than 6, gnathopod 2 slender, nearly simple; 

 coxa 2 much larger than coxa 1 and covering it, coxae 3 and 4 not 

 enlarged as in other cyphocarid genera; pereopods all prehensile; 

 telson long, deeply cleft. Species: 1, N.W. Pacific, abyssopelagic 



Metacyphocaris Tattersall 



Metacyphocaris Tattersall, 1906. 



Type-species: M. helgae Tattersall, 1906 (original designation). 



Head deformed; accessory flagellum 1-articulate; mandible with 

 very small, smooth molar, palp absent; gnathopod 1 simple, articles 

 5 and 6 equal; gnathopod 2 simple; coxae 1 and 2 small, partially 

 hidden by coxa 3; pereopods 1-3 prehensile; outer ramus of uropod 3 

 elongate, 2-articulate, inner ramus very short, scale-like; telson of 

 medium length, cleft one fourth. Species: 1, cosmopolitan, 

 bathypelagic. 



Metambasia Stephensen 



Melambasia Stephensen, 1923. 



Type-species: M. faeroensis Stephensen, 1923 (monotypy). 



Article 3 of male antenna 2 tumid; upper lip projecting slightly 

 in front of epistome; mandibular molar a long conical lamina, palp 

 attached level with molar; gnathopod 1 simple, article 5 longer 

 than 6; coxa 1 short, half as long as its second article, partially 

 hidden by coxa 2; inner ramus of uropod 2 constricted; telson cleft 

 halfway or more. See Schisturella. Species: 1, N. Atlantic, bathyal. 



