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



long and tapering lash, and from its base originates a narrow plate conformable to the 

 margin of the preceding, and on the inner side is a short, narrow, foliaceous branch of 

 great tenuity ; on the outer side, attached to the base, is a mastigobranchial plate that is 

 constricted near its middle, one-half of which is directed anteriorly and the other 

 posteriorly. 



The first pair of gnathopoda is subpediform and six-jointed ; the coxa carries a 

 mastigobranchia with a small podobranchial plume ; the basis supports a long and slender 

 ecphysis that is covered with a thick brush of hairs at its base ; the terminal two joints 

 are coalesced together, reflexed against the preceding joints, and furnished on the inner 

 surface with a thick brush of hairs, and at the lower distal angle, which corresponds with 

 the extremity of the dactylos, with two strong stout spines. 



The second pair of gnathopoda is pediform and five-jointed ; the coxa carries a 

 mastigobranchia with a short and rigid base supporting a membranous continuation of 

 rudimentary character, but there is no branchial plume connected with it, although two 

 small arthrobranchise are attached to the membranous articulation ; the basis carries a 

 short slender ecphysis, and the other joints are long, gradually taper to a truncated 

 extremity, and are fringed with numerous slender hairs that gradually become spine-like 

 at the extremity. 



The first pair of pereiopoda is slender, reaching nearly to the extremity of the 

 scaphocerite ; the coxa carries a short, rigid mastigobranchia, tipped with a sharp tooth 

 and fringed with hairs ; the basis in this as in the other pereiopoda is destitute of an 

 ecphysis, even of a rudimentary kind ; the ischium is connected with the meros by an 

 oblique and overlapping articulation ; the carpos is short, slightly increases distally, and 

 corresponds in diameter to the propodos, the palm of which is a little longer than the 

 pollex and dactylos that lie in opposition to each other. The second pair of pereiopoda 

 is constructed on the same plan as the first, differing only in being longer and slightly 

 more robust. The third, fourth, and fifth pairs are simple, long and cylindrical, having 

 the anterior distal angle of the carpos produced to overlap the propodal articulation, and 

 terminating in a sharp-pointed serrate dactylos that articulates with the propodos in a 

 thick brush of hairs. 



The pleopoda are biramose, the two plates resembling each other, being broad, flat, 

 and leaf-like, and nearly equal in length, the inner being the shorter, and both are fringed 

 with long rnultiarticulate and ciliated hairs. The first pair differs from the others both in 

 the male and female. In the latter the inner plate is shorter, broader, stiffer, and sparsely 

 fringed with short hairs, and the outer is still shorter, more narrow, with a sparsely 

 ciliated margin, and articulates at nearly a right angle with the inner, and when at rest 

 generally lies directed outwards between the posterior extremity of the pereion and the 

 anterior of the pleon. The second pah' carries two stylamblydes, both of which are short, 

 the outer is cylindrical, and terminates in a group of short cincinnuli, and the inner 



