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- Tryphosa nuga*. 



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 antennas 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. 1 20. 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 



