GAMMARIDEAN AMPHIPODA 103 



differs from A. synparls in the truncate lateral cephalic lobes and the 

 shorter lobes on the fifth articles of gnathopod 2. 



Mouthparts of A. edax are illustrated herein. Uropods and anten- 

 nae are missing from the several specimens. The aberrancy of the 

 head of the holotype is not a result of damage ; gnathopods and coxae 

 of other specimens are identical to those of the holotype. 



Bathymedon Sars 



Bathymedon caino, new species 



FlGUEE 47 



Diagnosis. — Rostrum long, slender, tapering, acute, almost straight, 

 reaching nearly three fourths along article 1 of antenna 1 and exceed- 

 ing lateral cephalic lobe; eyes absent; lateral cephalic lobe broad, 

 slightly concave distally but almost vertically truncated; epistome 

 and labral complex large, anteriorly flat from lateral view, projecting 

 well in front of head, rounded-off dorsally ; articles 1 and 2 of antenna 

 1 equal in length, article 3 about one third as long as either ; coxa 4 with 

 concave posterior edge forming postero ventral subacute lobe (miusual 

 for genus Batlujineclon) ; gnathopod 1 stouter but scarcely longer than 

 gnathopod 2, fifth articles slightly shorter than sixth, each pair of 

 appendages with posterior lobe on article 5 (large for Bathymedon), 

 lobes directed obliquely distalwards, thus partially guarding article 6, 

 lobes separated from article 5 by mediodistal excavation, article 4 

 with sharp posterodistal tooth, article 6 expanding distally, palm of 

 gnathopod 1 longer than posterior margin of article 6, slightly shorter 

 on gnathopod 2 ; article 7 of pereopods 1 and 2 longer than article 6 ; 

 anteroproximal surface of article 2 on pereopod 5 with nearly hori- 

 zontal and strongly submarginal ridge bearing setae (unusual for 

 Bathymedon), article 2 pyriform, posterior edge sloping slightly, 

 posteroventral corner slightly lobate; uropods missing or damaged; 

 telson truncated, bearing two large spines. 



Holotype.— AHF No. G133, female, 6.3 mm. 



Type-locality.— Station 7358, 27°35'45'' N, 115°08'30'' W, 1095- 

 1205 m, Apr. 21, 1961. 



Relationship. — The gnathopods, especially the second, of this spe- 

 cies resemble those of the genus Monocidodcs in that the posterior lobe 

 of article 5 partially guards article 6 but the mouthparts, especially 

 the mandibles, are those of a Bathymedon^ although the lacinia mobilis 

 on the left mandible is enlarged and that on the right mandible is sharp 

 (also occurring on B. acutlfrons Bonnier). Bathymedon caino forms 

 a link to Aceroides latipes (Sars, 1895, pi. 120, fig. 2) in its gnathopods. 



