CRUSTACEANS. 59 



chestes Mrtipalma, Dana, OrustaceaUDited States Exploring Expedition, 

 p. 888, pL 60, fig. 4, 1852) from the coast of Peru. According to the 

 description and figures, however, the propodus in the first pair of 

 gnathopods in that species is much narrowed proximally, the propodus 

 in the second pair is twice as long as broad, the palmary margin is 

 slightly emarginated in the middle, and there is no mention made of 

 any spine. The maxillae and maxillipeds agree well with the figures of 

 those appendages given by Dana. 



LYSIANASSID^. 

 Lysianassa kidderi, Smith, s. n. 



Eyes of moderate size, oval and black. Antero-lateral margin of the 

 head produced, nearly right-angled, with the angle very slightly rounded. 

 Basal segment of the peduncle of the antennula stout and about as long 

 as the head ; second and third segments very short ; flagellum scarcely 

 longer than the peduncle ; secondary flagellum about half as long. 

 Antenna in the female scarcely longer than the antennula ; all the seg- 

 ments of the peduncle ver^^ short; the flagellum tapering rapidly, and 

 composed of only seven or eight segments. In the young males the 

 antenna is much longer than tlie antennula, and the flagellum is com- 

 posed of twelve to fifteen segments, and furnished along the upper side 

 with vase-shaped sensory organs. 



First pair of gnathopods, not subcheliform, short; carpus much stouter 

 than the propodus and nearly as long; propodus tapering distally to 

 scarcely more than the breadth of the dactylus, which is stout, and not 

 more than a third as long as the propodus. Second gnathopods slender ; 

 carpus fully a third as broad as long, slightly narrowed distally; pro- 

 podus almost as wide but not as long as the carpus; the extremity 

 truncated, with the posterior angle produced into a small tooth opposed 

 to the minute hooked dactylus, which arises at its base and below the 

 middle of the terminal margin ; the posterior edge is armed with short 

 and acute spines, while the anterior edge and the sides are clothed with 

 slender setse, and the terminal margin, above the base of the dactylus, 

 with longer and stouter setce, curved at the tips. Coxae of the third 

 pair of pereopods broader than long. Posterior edges of the bases of 

 the third to the fifth pair evenly curved, with only very slight emargina- 

 tions at the insertions of the very minute and widely-separated marginal 

 hairs; the meral segments of the same appendages broad, and their 



