1392 THE VOYAGE OF H.M.S. CHALLENGER. 



the Plate. The centre of the figure is occupied by the Maxillipeds, the outermost 

 organs ; these have a wide base supporting a narrow stem, on which stand the two outer 

 plates, each of which has on its inner margin three small spines, one on the apex and one 

 on the outer margin just below it ; flanking the maxillipeds and partially concealed by 

 them are the Second Maxilhe; these in turn partially overlie the First Maxillse, the 

 curving palps of which nearly meet within and underneath the outer plates of the 

 maxillipeds ; the apices of these palps being turned edgewise to the spectator appear 

 narrower than they really are ; they have in fact a small spine at the inner angle and 

 a finely denticulate margin ; the Lower Lip is shut out of view ; the trunks of the 

 mandibles are seen on either side of the bases of the first maxillae, the outer margins 

 bending rather sharply round and meeting just where the outer plates of the maxillipeds 

 begin to separate ; the distal emargination of the Upper Lip is also seen within the 

 triangle formed by the separation of these plates. In the male the Mandibles have the 

 usual three-jointed palp. 



First Gnathopods. — The first joint as long as the four following together, dilated a 

 little at about the middle of the front margin ; the second joint not longer than broad ; 

 the third longer than the second, five-sided, with two slightly plumose spines on the 

 straight distal margin, which projects behind the wrist and has the corner adjoining the 

 wrist finely pectinate ; the produced wrist as long as the hand, much wider, with one 

 spine on the apex of the convex front, one on the straight hind margin, a larger one on 

 its apex, and two smaller ones within the apex ; the hand with one spine on the convex 

 front margin some way above the apex, the hind margin pectinate ; the finger curved, 

 more than half the length of the hand, with much of the inner margin finely pectinate. 



Second Gnathopods. — Branchial vesicles large, the upper part wide, the apical 

 narrowed. First joint a little longer than in the preceding pair, the base a little wider 

 than the part which follows and which is a little ridged on the inner surface ; the joint is 

 slightly widened below ; the remaining joints are similar to those of the first gnathopods, 

 but the second and third and the wrist are rather longer, the process of the wrist being 

 more elongate, beset with six spines. 



First Pereeopods. — Branchial vesicles large, as are also the following pairs. In the 

 figure br. four successive branchial vesicles are shown in their relative position over- 

 lapping one another. First joint bent at the narrow neck, then widening, rather longer 

 than in the second gnathopods ; second joint longer than broad ; third a little longer 

 than the second, narrow at the neck, then much widened, with one spine near the apex 

 of the almost straight hind margin ; fourth joint longer than the third, much broader 

 than the fifth, with a spine above the middle and a larger one near the apex of the 

 straight loosely pectinate hind margin ; fifth joint longer than the fourth, slightly curved, 

 with the hind margin pectinate ; the finger about half the length of the fifth joint, 

 slightly curved, with the inner margin near the base a little pectinate. 



