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



points on each margin ; the fifth a little curved, with spines at four points on each 

 margin ; the nail as in the preceding pair, but rather smaller. 



Fourth Perseopods. — The side-plates in shape much like those of the preceding segment, 

 but with the front margin straight instead of convex, and fringed with setiform spines, while 

 the lower margin behind is strongly spined. The first joint is longer and broader than in 

 the preceding pair, of even breadth for some way down, the convex front margin carrying 

 numerous setiform spines on the upper part, stronger groups of spines on the serrate lower 

 part, the hind margin serrate, fringed with many slightly plumose spines, the upper ones 

 curved ; the short second joint with two or three groups of small spines in front ; the long 

 third joint with spines at eight points of the front, and four of the hind margin ; the 

 fourth joint long and slender, shorter than the third, but longer than the fifth. 



Fifth Perieopods. — Side-plates deeper behind than in front, armed like the preceding 

 pair. The first joint shorter but broader than that of the fourth perseopods, the armature 

 similar, the front margin nearly straight, the hinder evenly convex ; the second joint 

 short ; the third shorter than in the preceding pair, with four groups of spines on the 

 front margin besides one or two spinules, three groups and a spinule on the hind margin, 

 which is scarcely decurrent, with the apex squared ; the fourth joint longer than the 

 third, and considerably longer than the fifth, with four groups of spines on each margin ; 

 the fifth joint with five groups of spines on the frout. and four on the hind margin ; the 

 finger as in the other perseopods ; this and the hand are twisted away from their normal 

 position in the Plate. 



Pleopods. — Coupling spines very small ; a sharply produced interlocking process 

 connects the peduncle and the first joint of the outer ramus ; cleft spines seven in 

 number on the first pair, six in the following pairs, the arms very short, and the outer 

 but little longer than the inner; in the specimen examined the number of joints of the 

 inner ramus of the third pair was twenty-one. 



Uropods. — Peduncles of the first pair a little longer than the rami, the inner ramus a 

 little longer than the outer, both with numerous marginal spines ; the peduncles of the 

 second pair longer than the outer ramus, shorter than the inner ; the rami, like those of 

 the first pair, tipped with spines and having many spines on the margins ; neither the 

 peduncles nor the rami reach back so far as those of the other two pairs; peduncles of 

 the third pair short ; the rami long, broadly lanceolate, bordered and tipped with spines, 

 subequal, the outer broader and a little the longer, reaching back as far or nearly as far 

 as the rami of the first pair. 



Telson short, 1 longer than the breadth at the base, cleft for three-quarters of its length, 

 little dehiscent, the slightly sinuous outer margins converging to the tolerably broad distal 

 margin, each half of which carries a spine and is produced to a small point on the inner 

 side. There are some cilia on the surface. 



1 Contrary to the generic character, not longer than the peduncles of the third uropods. 



