1322 THE VOYAGE OF H.M.S. CHALLENGER. 



distally scabrous, which perhaps represents in rudiment the inner plate of the maxilla ; 

 beyond this there are two or three pricldes and a very small spine tooth, which is 

 followed by the sharply double-pointed apex, whence fifteen or sixteen small acute teeth 

 descend the convex outer margin, gradually weakening into faint serrations, all the 

 lower part of the margin being smooth. 



Maxillipeds. — The first joint, which in the separate figure mxp is for the sake of dis- 

 tinctness unfolded, in its natural position is bent at a sharp angle to the second joint, so 

 that when the maxillipeds are separated from the head, the first and second joints naturally 

 close together ; the inner plate strongly prismatic, one edge centrally projecting inwards, 

 this edge starting some way below the distal margin of the second joint ; at its apex 

 there is a small interval between the concave distal margins of the two sides, each of 

 which carries two small separated spine-teeth near the inner and lower end ; the front 

 of the plate also has a concave distal margin, with a small central emargination and two 

 or three little spine-teeth spaced along the slightly serrate margin on either side of 

 this ; the outer surface of the plate is not distinctly marked off from that of the second 

 joint, except that in the centre of what may be considered as its base-line, there is a 

 small conical tooth ; on either side of this are planted the two outer plates, which after 

 widening a little from their bases, narrow to an acute apex ; the outer margin is 

 smoothly convex, the inner carries two spinules at intervals not far from the base, and 

 then is cut into strongly marked teeth as follows, a very small, a larger, a larger still, 

 a rather small, a very large, a less large, a rather small, a large, a small, a moderately 

 large, the apical largest of all, with a small tooth on its inner side ; the two plates, 

 however, are not symmetrical, since that on the right hand in place of the twelve teeth 

 just mentioned has but ten, the first of them, however, being a double tooth. 



First Gnathopods. — The side-plate represented by an outward projecting tooth. 

 The limb about eight-twentieths of an inch long, the first joint as long as the next four 

 together, widening a little distally for the strong muscles which are grouped in the 

 distal portion ; the front margin having on one gnathopod six strong teeth and three 

 small ones, on the other having eight less unequal teeth ; the hind margin is nearly 

 smooth, but the apex is produced into a sharp tooth, and above this there are on one 

 gnathopod two, on the other three, small teeth and a spinule ; the second joint much 

 broader than the length of its front, apically produced behind in a strong tooth, at the 

 base of which there is a very small tooth on the hind margin ; the third joint longer 

 than broad, clasping the wrist, with scarcely any free front margin, the surfaces 

 carrying some slender spines, of which there are some on the more or less deeply 

 emarginate apex, and on one gnathopod one on the otherwise smooth hind margin, 

 while the other gnathopod has three ; the wrist with the front margin longer than the 

 hand, apically forming a small tooth, otherwise smooth, triangularly produced behind 

 almost to the extremity of the long apical tooth of the hand ; on the outer surface 



