648 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxviii. 



emarginate appearance. Abdomen entirely lacking, or onty appear- 

 ing in the faintest traces on the ventral surface of the genital segment. 

 Anal laminae as in other genera, not at all degenerate, but attached to 

 the ventral surface of the genital segment owing to the absence of the 

 abdomen. Their exact position varies considerably in different speci- 

 mens, but they are usually attached some little distance in front of the. 

 posterior border. For this reason they are wholly, or almost wholly, 

 concealed in dorsal view, only their tips or the setae attached to them 

 appearing beyond the edge of the genital segment. 



First antenna? small and plump, the joints about even and armed as 

 in other genera; second pair with a large terminal claw bent at a 

 sharper angle than usual. 



First maxilla? rather large and plump, not much swollen at the base; 

 second pair little more than half as long as the mouth tube, separated 

 from it quite a distance on either side, simple and pointed, with a 

 greatly enlarged base. 



Mouth tube large, twice as long as wide, and well rounded at the 

 end. Eyes small, situated posterior to the base of the mouth tube, the 

 lenses separated by about twice their own diameter. First maxillipeds 

 with a blunt lobe on the middle of the inner margin of the terminal 

 joint. Second pair very large and strong, the basal segment much 

 swollen but without knobs or spines, the terminal claw stout, bent 

 abruptly, and without any accessory spine on the inner border. 



Furca small, plump, the basal part slightly longer.than the branches, 

 with a membranous frame and large oval foramen. 



The branches are simple, parallel and club-shaped, with obtuse ends; 

 the sinus between them is long and very narrow. 



There is no spine at the distal corner of the terminal joint of the 

 first thoracic legs, but only the three terminal claws, the longest of 

 which is about the length of the joint. 



Second swimming legs as in Caligus. Third pair different from the 

 genera already described; the basal lamina? are larger and the rami 

 are not attached to their posterior border or at the posterior corners, 

 but high up on the lateral borders and close together so that they par- 

 tially overlap. 



Furthermore the endopod consists of but a single segment, armed 

 with three strong^ curved bristles which hardty deserve the name of 

 plumose seta?. The exopod is two- jointed and but scantily armed. 

 The fourth legs are small but comparatively strong, three jointed, the 

 basal joint as long as the other two. There is a spine at the end of the 

 second joint and three on the terminal joint, all so close together as to 

 form a single bunch or cluster. 



The fifth legs appear as a pair of very stout and long papilla? pro- 

 jecting from the posterior corners of the genital segment, each ending 

 in a single stout spine. 



