1604 THE VOYAGE OF H.M.S. CHALLENGER. 



The Mandibles are very short, with a tolerably broad striated cutting edge, the 

 secondary plate of the left mandible nearly as long as the principal, but without the 

 projecting tooth at the upper angle. 



The Maxillipeds are very small, not elongated ; the inner plate short, distally beset 

 with little setules ; the outer plates arching over it are almost as broad at the base 

 as their length ; their sinuous inner margin has a wrinkled or striated appearance. 



First Gnathopods. — The side-plates deeper than wide ; serrate about the lower 

 front angle, which is pointed forwards. The first joint broader above than below, the 

 second very short, the third broader than long, wrist-like ; the wrist very large, the 

 convex front margin projecting a little in front of the hand, not apically produced, 

 the hind margin set with small, unequal, partially feathered spines, much of it finely 

 pectinate, the distal part cut into seven teeth, the apes strongly produced, the broad 

 almost straight or slightly sinuous palmar margin within the apex cut into six or eight 

 unequal straight teeth, submarginal to which on both surfaces are rows of many spines 

 of various sizes ; the hand shorter than the wrist and not half the width, widening a 

 little from the neck and contracting again near the finger, with the front margin 

 convex, at first smooth but distally set with spines, of which there are many on the 

 surfaces and adjoining the straight, crenulate, and denticulate hinder margin, the apex 

 of which is acute and produced to about half the length of the finger, its inner margin 

 having one or two denticles; the finger is little curved, and has a denticle near the 

 middle of the inner margin. 



Second Gnathopods. — Branchial vesicles broader and longer than the first joint. 

 The first joint with the hinder apex strongly outdrawn ; second and third joints as in 

 the first pair ; the wrist much larger, similarly armed, except that the very elongate 

 hind margin is not pectinate or toothed, the inner margin within the very elongate apex 

 is cut into five or six teeth; the hand though not dissimdar to that of the first pair is 

 narrower in appearance and much longer ; the finger is also rather longer and the 

 produced apex of the hand does not reach the middle of it ; the much greater length 

 of the apical tooth of the wrist and its oblique distal margin give to these gnathopods a 

 claim to be regarded almost as complexly chelate instead of subchelate. 



First Perseopods. — Side-plates with the front margin convex. Branchial vesicles 

 longer and much broader than the first joint, with two lateral accessory pockets, rather 

 longitudinal than transverse, in the upper half. The first joint not quite so long as the 

 third and fourth joints together ; the fourth rather longer than the third, the fifth much 

 narrower than the fourth, as long as the third, curved, having like the two preceding 

 joints outstanding spinules along the hind margin, but small ones ; the finger slight, less 

 than a third of the length of the fifth joint. 



Second Perseopods like the first, but with all the joints longer, and the third rather 

 longer than the fourth. 



