368 THE VOYAGE OF H.M.S. CHALLENGER. 



on the posterior margin in the median line there is a solitary, erect, spine-like process, 

 fringed with teeth on the dorsal surface, and on each side, at the lateral margin, slightly 

 anterior to the mandibles, between them and the anterior spinous process, there arises a 

 short but prominent spine fringed with teeth. 



The pleon has the five anterior somites subequal, smooth on the dorsal surface, but 

 armed at the postero-lateral margin of each with a long spine-like process, fringed with 

 sharp teeth. 



The sixth somite is but little longer than the fifth ; it is unarmed at the postero- 

 lateral angles, but carries a small tooth on the posterior margin of the dorsal surface. 



The telson is short and bifurcate, the caudal fork being short and broad. 



The ophthalmopoda are about two-thirds the length of the rostrum, gradually 

 increasing in diameter from the base to the distal extremity, wbere the ophthalmus is 

 slightly broader than the stalk, more distinctly apparent on the outer than on the 

 inner side. 



The first pair of antennas consists of one long joint, fringed with hairs, that reaches 

 as far as the distal extremity of the rostrum, and terminates in two small single-jointed 

 rami tipped with one or two small hairs. 



The second pair of antennas consists of a broad basal joint, an inner multiarticulate 

 branch that corresponds to the future flagellum, and a long, narrow, foliaceous branch 

 that corresponds to the future scaphocerite, the outer margin of which is smooth, and 

 furnished at the outer angle of the distal extremity with a small tooth, while the inner, 

 which is parallel with the outer, is thin and fringed with hairs. 



The mandibles are sharp-pointed and do not appear to carry a synaphipod. 



The other oral appendages I have not determined, except the third pair of siagnopoda 

 or first maxillipede, which is in an immature condition, biramose, and tipped with one 

 or two long hairs. 



The first and second pairs of gnathopoda are biramose and correspond in develop- 

 ment with the third pair of siagnopoda. The pereiopoda are all in a very similar 

 condition. 



The pleopoda are in a very immature stage of gemmation, except the sixth pair, 

 which is long, slender, biramose, and well developed ; it consists of a basal joint armed 

 with a tooth on the outer distal angle, and supporting two long, narrow, slender branches, 

 with subparallel margins. The outer, which is the longer, is smooth on the outer margin 

 to about one-third of its length, where it is armed with a short strong tooth, beyond 

 which, it is fringed with short hairs to the distal extremity, while the inner margin is 

 fringed with long hairs, which are probably ciliated. The inner branch is straight, 

 narrow, tapering, and fringed with hairs, probably ciliated. 



Length, 4 mm. (0"16 in.). 



Habitat. — The Western Pacific Ocean. 



