1054 THE VOYAGE OF H.M.S. CHALLENGER. 



First Gnathopods.- — Side-plates much wider below than above, directed forwards so as 

 to cover the basal joints of the lower antennae, the strongly convex lower margin closely 

 fringed with long setae, the hind margin nearly straight, ending in a sharp, curved apical 

 tooth, which does not reach so low as the lower margin. The first joint not reaching 

 the end of the side-plate, widening distally, armed as usual; the second joint having 

 much of the hind margin fringed with feathered setae ; the third joint oval, apically 

 pointed, with many spines along the hind margin and across the distal half of the inner 

 surface ; the wrist with the front margin little convex, the free hind margin convex, 

 crowded with spines, many of which are conspicuously pectinate to the tip ; the inner 

 surface has rows of long spines near the hind margin, and smaller groups near the front ; 

 the hand is rather narrowly oval, longer than half the wrist, with the palm not well 

 marked, the spines on the hind margin pectinate at the centre ; the inner surface having 

 half a dozen spines along the centre and others near the front margin ; the apical spines 

 are long ; the finger is rather short, the nail narrowing almost abruptly, not half the 

 length of the upper part of the finger ; the spinules of the inner margin are four or five 

 in number, pectinate, the series beginning near the base of the nail. 



Second Gnathopods. — Side-plates elongate, widening a little distally, the hind 

 margin with a small apical tooth, the very convex lower margin strongly fringed. The 

 branchial vesicles widening from a narrow neck, for the most part of even breadth 

 to the end, longer than the first joint. The marsupial plates narrow, no setae present. 

 The first joint not nearly reaching the end of the side-plate, curved forwards, a few long- 

 setae on the lower half of the convex hind margin ; the second joint with a couple of 

 setae on the apex of the hind margin ; the third joint rather broad, the hind margin 

 nearly straight, smooth, the truncate distal margin having one feathered seta ; the wrist 

 narrow, with only a few spines at intervals on the margins and inner surface ; the hand 

 narrow, more than half the length of the wrist, with the hind margin free from spines 

 for more than half its length, then carrying six or seven ; there are eight or nine spines 

 or setae on the inner surface, and as many on the front margin and its apex ; the finger 

 is short, with five pectinate setules on the inner margin close to the base of the not 

 elongated nail. 



First Perseopods. — Side-plates rather wider below than above, the hind margin with a 

 small apical tooth, the lower convex, well fringed. The branchial vesicles shorter than 

 the side-plates, as long as the first joint, tending to oval, but with the front side flattened. 

 The first joint not reaching the end of the side-plate, the front margin straight, the hind 

 convex, with the usual armature ; the second joint short ; the third long, nearly parallel- 

 sided, fringed with many long plumose setae ; much of the upper part of the front margin 

 appears to be bare, but there are setae on the inner surface, which might project beyond 

 this margin ; the fourth joint, which is longer than broad, has eight groups of long 

 plumose setae on the hind margin, and one or two spinules on the front apex ; the fifth 



