MARINE GAMMARIDEAN AMPHIPODA 381 



Arrhinopsis S tappers 



Arrhinopsis Stappers, 1911. 



Type-species: A. longicornis Stappers, 1911 (monotypy). See 

 Gurjanova, 1951. 



Cutting edge of mandible projecting, toothed, molar bulging, 

 setulose, but unridged; inner lobes of lower lip separate; gnathopods 

 similar to each other, subchelate, moderately stout, lobe of article 5 

 long and guarding article 6; uropod 2 reaching end of uropod 3. 

 Species: 1, arctic, littoral. 



Arrhis Stebbing 



Aceros Boeck, 1861 (homonym, Aves). 

 Arrhis Stebbing, 1906 (new name). 



Type-species: Leucothoe phyllonyx M. Sars, 1858 (original designa- 

 tion and subsequent synonymy). See G. O. Sars, 1895. 



Cutting edge of mandible not projecting, untoothed, molar large, 

 ridged; inner lobes of lower lip separate; gnathopods similar, subchelate 

 moderately stout, article 5 with sharp posterior lobe pointing distally; 

 uropod 2 reaching end of uropod 3; mandibular palp article 2 strongly 

 curved (Aceroides). Species: 3, arctic, littoral to abyssal. 



Bathymedon Sars 



Bathymedon Sars, 1895. — Stebbing, 1906 



Type-species: Halimedon longimanus Boeck, 1871 (original desig- 

 nation). See Sars, 1895. 



Cutting edge of mandible not projecting, untoothed, molar large, 

 ridged; inner lobes of lower lip separate; gnathopods somewhat 

 similar to each other, usually gnathopod 2 more slender, posterior 

 lobe of article 5 moderately developed in gnathopod 1, becoming 

 obsolescent occasionally in gnathopod 2; uropod 2 reaching end of 

 uropod 3; "article 2 oj mandibular palp not as curved as in Westwood- 

 illa." Species: 16, cosmopolitan coldwater, littoral to abyssal. 



Bathyporeiapus Schellenberg 



Bathyporeiapus Schellenberg, 1931. 



Type-species: B. magellanicus Schellenberg, 1931 (monotypy). 



Cutting edge of mandible projecting, toothed, molar large, ridged; 

 inner lobes of lower Hp separate; gnathopods somewhat dissimilar, 

 slender, gnathopod 1 subchelate, gnathopod 2 simple; uropod 2 

 apparently only slightly exceeding peduncle of uropod 3. Species: 

 1, antiboreal, littoral. 



