1192 THE VOYAGE OF H.M.S. CHALLENGER. 



straight, directed obliquely forwards, joining the straight lower margin by a narrowly 

 rounded corner, the depth less than the greatest breadth. The first joint nearly free from 

 the side-plate, narrow at the neck, almost unarmed; the second joint short, with a spinule 

 at the front lobe, and some slender spines on the apex behind ; the third joint a little 

 longer than the second, wider above than below, with a group of spines near the middle 

 of the front margin, and several spines round and near the curve which joins the convex 

 hinder with the sinuous distal margin ; the wrist about as long and as broad as the hand, 

 narrowest at the two ends, the front margin convex, with three small groups of spines 

 near it, the hind margin fringed with many feathered spines, of which the surface has 

 various groups ; the hand broad-oval, with six or seven groups of rather long spines along 

 the convex front margin, which is almost continuous with that of the wrist ; the hind 

 margin, most of which may be regarded as a palm, is fringed with many feathered spines, 

 and there are various groups of spines on the inner surface; the finger is short, curved, 

 and broad, a good deal stouter than the hand, with a small dorsal cilium near the base, 

 the inner margin having a sharp decurrent tooth beyond the middle, and a longer one at 

 the base of the sharp nail. 



Second Gnathopods. — The side-plates small, broader than deep, with a spinule at the 

 front corner of the lower margin. Branchial vesicles oval, much larger than the side- 

 plates, as long as the first joint, and much broader. The first joint nearly free from the 

 side-plate, rather larger than in the first gnathopods, about as long as the hand, with 

 four spines on the convex hind margin ; the second joint with two or three spines at the 

 apex behind ; the third joint with convex front and hind margins, the latter carrying at 

 the rounded apex a group of three or four spines, above which are two other groups ; the 

 wrist shorter than the third joint which completely overlaps it behind, a little wider than 

 long, distally cup-like, but with the distal margin convex, with a few spines round the 

 apical part before and behind ; the baud large, broad oval, much wider than the wrist 

 from the very base, with spines singly or in groups at six or seven points round the front 

 margin, at several points along the inner surface, at a little distance from and others near 

 the hind margin, which has three or four groups on the proximal part, and is then 

 distinguished from the palm by a minute tooth or notch, near to which are planted two 

 palmar spines ; the palm itself, which forms more than half the convex hind margin, has 

 no spines actually on the rim, though many submarginal ; the finger is broad, as long as 

 the palm, with a small decurrent tooth on the inner margin at the base of the nail ; and 

 five minute spine-teeth at intervals of the otherwise smooth inner margin, with a few 

 subrnaroinal setules. 



First Perseopods. — Side-plates and the branchial vesicles as in the preceding segment. 

 The first joint almost free from the side-plate, narrow at the neck, then expanding on both 

 sides, the hind margin having spines at two or three points of the upper half, and at the 

 apex, the front margin convex, forming a winged expansion, fringed with six or seven 



