REPORT ON THE AMPHIPODA. 1281 



outer margin ; the inner surface has many cilia or hair-like spines near the inner 

 margin, and the outer surface carries a curved row of about a dozen small spines at 

 some distance from the inner margin. 



First Gnathopods. — Side-plates small, broader than deep, with rounded front. The 

 first joint long and broad compared with the rest of the limb, the margins smooth, the 

 hinder more evenly convex than the front which bulges a little above the centre, 

 the distal margin carrying two or three small spines ; the second joint not longer than 

 broad, with some spines near the apex of the hind margin ; the third joint very little 

 longer than the second, almost triangular, with a strong spine at the apex of the hind 

 margin and a smaller one above ; the wrist a little longer and wider than the hand, 

 the hind margin nearly straight, with a spine at the apex and a smaller one near it 

 above, the front margin with a group of small spines at the apex, the distal margin 

 sinuous, minutely pectinate ; the hand widening a little from the base, then narrowing 

 to the apex, with three spines on the distal half of the very convex front margin, the 

 hind margin nearly straight, pectinate for most of its length with little teeth ; the 

 finger narrow, curved, acute, a little more than half the length of the hand, the 

 proximal half of the inner margin pectinate. Almost all or all the spines are more or less 

 feathered or denticulate. 



Second Gnathopods. — The side-plates much broader than deep, the front rounded. 

 The branchial vesicles very large, much longer and broader than the first joint, narrowing 

 to a rounded tip ; the marsupial plates nearly as long as the first joint, rounded oval, 

 very broad, finely scabrous. The first two joints similar to those of the first gnathopods, 

 but rather larger, the second with two spines on the hind margin ; the third joint longer 

 than the hand, overlapping a large part of the wrist on the inner side, the hind margin 

 carrying eight spines, those at the distal part the longest, feathered ; the distal margin 

 truncate, armed with five or six stout spines that have hooked tips, and are more or less 

 denticulate ; the wrist is broader than the hand, and longer even without the narrow 

 acute process by which it overlaps more than half the hand's hinder margin ; the front 

 margin has an apical spine ; the process is denticulate on one of its inner edges and 

 finely pectinate on the other, the two edges not being in view together ; the hand and 

 finger are as in the first gnathopods, except that the hand is scarcely so broad, the spines 

 of its front margin are more slender, and the finger is not more than half the length of 

 the hand. 



First Peraeopods. — Side-plates rather broader than deep, like the two preceding pairs 

 narrower in front than behind, the front maroin flatter. The branchial vesicles and 

 marsupial plates large. The first joint with sinuous front margin,, convex above, concave 

 below, the hind margin convex, except at the base ; the second joint short ; the third 

 longer and broader than the fourth ; the fourth with a straight hind margin, the front 

 convex, the distal margin of the inner surface pectinate ; the fifth joint narrower than the 



(ZOOL. CHALL. EXP. PAET LXVII. — 1888.) XxX 161 



