1002 THE VOYAGE OF H.M.S. CHALLENGER. 



channelled behind, curved, widening slightly from the base, then narrowing to the apex, 

 the front margin convex, with some slight spines at intervals, the hind margins carrying- 

 spines of very various lengths ; the finger narrow and elongate, about half the length of 

 the hand, with a dorsal cilium at about two-thirds of the length from the base, the inner 

 maro-in nearly straight, with some short setules at intervals, and a series of four or five 

 near the base of the nail, which is preceded by a strong nail-like tooth, between which 

 and the actual curved nail there is a cilium. 



Second Gnathopods.- — The side-plates broader than deep, the front margin nearly 

 straight, the lower very convex. The branchial vesicles narrow, lageniform, rather longer 

 than the first joint, which they exceed in width. The marsupial plates longer than the 

 branchial vesicles, fringed with very long setae, which are distant except at the apex. 

 The first joint channelled in front and a little convex, with spinules along the margins ; 

 the second joint short, with a group of several long and short setiform spines at the apex 

 behind ; the third joint produced to a long acute apex, the hind margin fringed with 

 setiform spines, those near the apex of very great length ; the wrist much longer than 

 the third joint, and longer than the hand, with a few spines on the long front margin and 

 at its apex ; the hind margin where free from the third joint is slightly convex, and 

 densely fringed with numerous groups of setiform spines of various lengths, some very 

 long indeed ; the hand widening a little from the base, then narrowing to the apex, the 

 front margin very convex, with few spines, the hind margin gently concave, densely 

 fringed with spines, more closely set than those on the wrist, but not so long, and having 

 a few spines longer and stiffer than the rest, finely pectinate, with the ends flexible ; the 

 finger more than half the length of the hand, nearly as in the first gnathopods, but the 

 tooth on the inner margin slighter. 



First Perseopods. — The side-plates simdar to the preceding pair, but rather deeper ; 

 the branchial vesicles also rather larger, and the marsupial plates longer. The first joint 

 almost entirely free from the side-plate, with a few slender spines on the front and at the 

 apex of the hind margin ; the second joint short, with a group of setiform spines on the 

 apex behind ; the third joint widening distally, shorter than the fourth, with setiform 

 slightly feathered spines at six or seven points of the hind margin, and apex in front ; 

 the fourth joint elongate oval, the hind margin fringed with many long slender spines ; 

 the fifth joint subequal in length to the fourth, or a little longer, but narrower, the hind 

 margin serrate, with seven groups of spines ; the finger long and slender, more than half 

 the length of the fifth joint, straight till near the tip, the edges with a finely pectinate 

 appearance. 



Second Perzeopods scarcely distinguishable from the first. 



Third Perieoj>ods. — The side-plates considerably larger than the preceding pairs, 

 broader than deep, deeper in front than behind, the front margin oblicme, the lower 

 margin nearly straight, with a very slight convexity. The limb very long, its first j oint 



