1286 THE VOYAGE OF H.M.S. CHALLENGER. 



Remarks. — It seems probable that this form may be one of the numerous species 

 from the Atlantic which have already received names, otherwise the differences scarcely 

 suffice to separate it from the eastern species, Vibilia propinqua. 



Vibilia viator, n. sp. (PL CXLVIIIb. fig, E). 



The dorsal depression deep where the fifth and sixth segments of the pleon coalesce, 

 but with no separation between them. 



Eyes large and dark. 



Upper Antennw with the upper margin of the large flagellum joint much longer 

 than the lower, the end of the joint being oblicpaely truncate. 



Lower Antennae. — The flagellum in this specimen exhibiting six joints. 



Upper Lip. — The smaller of the distal lobes distinctly serrate, neither strongly 

 ciliated. 



Mandibles. — The cutting edge divided into sixteen teeth ; the strap-like secondary 

 plate of the right mandible having four little slender teeth at its apex, one much longer 

 than the other three ; the first two spines of the spine-row on each mandible much 

 widened distally and there, cut into several little teeth, not so strong as those of the 

 secondary plate on the left mandible, but stronger than the teeth of that plate on the 

 right mandible. 



First Gnathopods. — The first joint with the front margin not bulging, the hinder 

 apex set about with five spines ; the second joint with three spines about the hinder 

 apex ; the third joint with three spines on the hind margin ; the wrist wider, but 

 not longer, than the hand, having a spine at the apex of the convex front margin, and 

 three at and near the apex of the straight hind margin ; the hand with two spines 

 adjacent to the convex front, the pectination of the straight hind margin continued 

 round the slightly prominent apex ; the finger more than half the length of the hand, 

 the upper half of the inner margin pectinate. 



Second Gnathopods not very different from those of Vibilia 'propinqua, but perhaps 

 not quite in the normal condition, since in one the third joint is unusually short, and in 

 the other the process of the wrist is very short and apically rounded, instead of acute as 

 in the companion limb. 



First Perseopods. — The third joint is narrow at the base, and then widens greatly, 

 with very convex front margin, the length a little exceeding that of the fifth joint ; the 

 fifth joint, is longer than the fourth, scabrous along the hind margin ; the finger elongate, 

 subequal in length to the fifth joint. 



Second Perseopods similar to the first. The remaining pairs differing little from 

 those of Vibilia propinqua, the fingers broken. 



Pleopods. — Joints of the rami eleven in number in the pair examined. 



