AMPHIPODS 



235 



as long ; the fifth pair about as broad as deep. Postero-lateral angle of 

 the third abdominal segment nearly a right angle, the posterior margin 

 of the epimeral plate 

 above the angle smooth 

 and straight. Fourth 

 abdominal segment but 

 slightly concave dorsally. 

 First joint of the first 

 antennae very thick and 

 somewhat produced dis- 

 tally over the second 

 joint; flagellum scarcely 

 as long as the peduncle, 

 and composed of six or 

 seven joints, the first joint FlG - "9- 



but little longer than the succeeding one ; secondary flagellum short and 

 rather stout, consisting of four joints, of which the first is nearly as long 

 as the three others. Second antennae a little longer than the first pair ; 

 flagellum not so long as the peduncle. Molar tubercle of the mandibles 

 situated about midway between the cutting edge and the insertion of the 

 palp. Inner plate of the maxillipeds reaching nearly as far forward as 

 the tip of the second joint of the palp, and armed distally with a few 

 short teeth ; outer plate reaching about to the middle of the third joint 



FIG. 120. Tryphosa nugax. 



of the palp, and armed distally and around the inner angle with several 

 short teeth. First gnathopods with the hand rectangular, not tapering 

 distally, the palm transverse, nearly straight, and armed posteriorly with 



