604: " THETIS " SCIENTIFIC RESULTS. 



about two-and-a-half times longer than the third. This last 

 differs little in appearance from the neighbouring joints of the 

 flagellum, which are in all about ten in number, slender, with 

 filaments on the apical joint. In the male the second joint of 

 the peduncle is of the same shape as in the female, but longer than 

 the first joint. The second antennse, shorter than the first, have 

 the peduncle as in the male, but the flagellum seemingly con- 

 sisting of a single conical joint, but perhaps three-jointed, slightly 

 shorter than the last joint of the peduncle. The antennae of 

 P.Jissicauda show several differences, and have in the first pair 

 a flagellum of eighty-five joints and one of fifty in the second. 



The upper lip has no emai'gination of the convex distal border. 

 The lower lip agrees with P.facijica and P.Jissicauda in having 

 well-developed inner plates and the apices of the mandibular pro- 

 cesses upturned. The small, undoubtedly one-jointed palp of the 

 first maxillae has apically three setae. The inner plate of the second 

 maxillae is much shorter than the outer, both apparently with 

 scanty armature. The inner plates of the maxiilipeds are well- 

 developed, though very short, carrying spines and perhaps spine- 

 teeth on their truncate apices. The representation of these in 

 the " Challenger " Report must be regarded with suspicion, as 

 indeed is intimated in the text. 



Both pairs of gnathopods have the sixth joint distally truncate 

 with the transverse palm in the first pair quite straight, and in 

 the narrower second scarcely convex, and only very slightly 

 oblique, forming less than a right angle with the hind margin, 

 not more, as in the other two species. 



In all the peraeopods, except the fifth pair, the fourth joint is 

 longer than the fifth, but in the fifth pair, which is shorter than 

 either of the two preceding pairs, this proportion is reversed. The 

 second joint is oblong in the third, pear-shaped in the fourth, 

 and rotundo-quadrate in the fifth pair, its front margin in 

 this last being nearly straight, but the hind margin very much 

 rounded and more strongly serrate than in the other two 

 pairs. In the specimens examined the branchial vesicles were 

 narrow. 



The pleopods are of no great strength. The other appendages 

 may be described in Monsieur Chevreux' terms as applied to his 

 P. Jissicauda. First uropods elongate, branches longer than the 

 peduncle ; second pair very short, inner branch longer than the 

 outer ; third pair reaching the level of the extremity of the first 

 pair, branches lanceolate, much longer than the peduncle, and 

 edged with small spines. Telson much longer than the peduncle 

 of the third uropods and cleft to the base. It is a question 

 whether in our species the second uropods should be called very 



