GAMMARIDEAN AMPHIPODA 109 



fumtlus J. L. Barnard (1962d) , a sympatric sublittoral relative, has an 

 emarginate telson, narrower third and fourth coxae, a more strongly 

 projecting posterior lobe on article 2 of gnathopod 1, an even less- 

 developed posterior lobe on gnathopod 2 and more slender pereopods 



1 and 2 than does B. -fiebilis. 



Distribution. — Middle Baja California, 1748-2398 m. 



Bathymedon nepos, new species 

 Figure 50 



Diagnosis. — Eostrum long, slender, tapering, acute, nearly straight, 

 reaching nearly two-thirds along article 1 of antenna 1 and exceeding 

 lateral cephalic lobe ; eyes absent ; lateral cephalic lobe subacute, mar- 

 gin below point oblique ; epistome subquadrate in front but not acutely 

 produced forward ; article 2 of antenna 1 longer than article 1, article 

 3 half as long as article 1 ; coxa 4 with concave posterior edge forming 

 posteroventral subacute lobe ; gnathopods equal in stoutness, fifth ar- 

 ticles shorter than sixth, each pair of appendages with short, broad 

 posterior lobes directed slightly distalwards, lobes separated from 

 article 5 by mediodistal excavation, article 4 of gnathopod 2 with 

 sharp posterodistal tooth, tooth of gnathopod 1 blunt and obsolescent, 

 article 6 expanded distally, palms shorter than posterior margins of 

 sixth articles ; article 7 of pereopods 1 and 2 as long as article 6 ; article 



2 of pereopod 5 subpyriform, posterior edge sloping strongly and ar- 

 ticle 2 thus tapermg, posterodistal comer quadrate, imlobed, and 

 scarcely projecting from tangent of article 3; telson trmicate or 

 perhaps scarcely emarginate, sparsely setose. 



HoLOTYPE. — AHF No. 6020, male, 10,4 mm. 



Tyte-locality.— Station 7230, 27°52'25'' N, 115°44'30'' W, 26G7- 

 2706 m, Dec. 31, 1960. 



JVIaterial. — Two specimens from the type-locality. 



Relationship. — This species differs from Bathy7nedon longimanus 

 (Boeck) (see Sars, 1895, pi. 117) and B. acutifrons Bonnier (1896) in 

 the short fifth article of gnathopod 2 and from B. saussurei (Boeck) 

 (see Sars, 1895, pi. 117, fig. 1) by the stouter, less elongate second 

 gnathopod. Bathymedon ivanovl Bulycheva (1952) has a shorter, 

 blunter rostrum and longer fifth article of gnathopod 2 than does 

 B. nepos. 



The new species differs from B. roquedo J. L. Barnard (1962d) in 

 the better development of the gnathopods, which have more rectang- 

 ular and less triangular sixth articles, by the absence of eyes, the more 

 slender rostrum, and the shorter telson. 



