1498 THE VOYAGE OF H.M.S. CHALLENGER. 



first joint a bristle near the apex of the hind margin ; the third joint longer than the 

 wrist, with four bristles on the front and two on the straighter hind margin ; the wrist 

 with five bristles on the convex front margin and four, of which the lowest is the longest, 

 on the almost straight hind margin, of this the apex being narrowly and smoothly 

 rounded, standing off from the hind margin of the hand and a little produced ; the hand 

 scarcely so long as the wrist, much narrower, tapering, having one bristle near the apex ; 

 the finger very small, curved, carrying one short bristle, and perhaps a denticle on the 

 inner margin near the apex. Gland-cells can be traced in the first four joints of this and 

 the following pair. 



Second Gnathopods similar to the first pair but longer, especially in respect of the 

 first and third joints. The branchial vesicles of comparatively enormous size. The first 

 joint sinuous, only slightly widened below, carrying one bristle near the apex of the hind 

 margin and another rather higher up ; the hinder apex of the wrist a little more narrowly 

 produced than in the preceding pair ; the hand not longer. 



First Perseopods. — Side-plates longer than the preceding pair. Branchial vesicles 

 like the preceding and following pairs of great size. First joint similar to that of the 

 second gnathopods, but longer and more slender, smooth ; the second joint longer than 

 broad ; the third subequal in length to the fourth but rather shorter, with a bristle at 

 the apex in front, one at the apex behind, and two widely apart higher up ; the fourth 

 joint rather more bent than the third, with four or five bristles along the hind margin ; 

 the fifth joint shorter than the fourth, straight except at the base, tapering, with three 

 small bristles on the hind margin ; the finger as in the gnathopods, very small. 



Second Perseopods similar to the first, but with the joints rather longer, and larger 

 side-plates. 



Third Perseopods. — Side-plates broader behind than in front, larger than the 

 preceding pair, having a strongly bent tooth on the inner surface. First joint large 

 (yet not so large as the branchial vesicles), broadly and almost regularly oval, with five 

 little setules at the lower end of the front margin, length of the joint almost equal to 

 that of all the following slender joints together; just below the tooth of the side-plate 

 there is as usual a fold on the inner surface of this joint ; second joint longer than 

 broad, rather deeply socketed in the distal end of the first joint ; the third joint shorter 

 than the fourth, the fourth a little longer than the fifth, these and the finger being 

 similar to those of the preceding peraeopods, but the fourth and fifth of greater length. 

 In all the limbs it is possible that the finger may have some pectination and some 

 other armature than a spinule of the inner margin near the tip, but the characters were 

 too minute to be more than guessed at. 



Fourth Perseopods. — The side-plates much larger than any of the other pairs, much 

 deeper behind than in front. The branchial vesicles much larger than the side-plates but 

 much smaller than the first joint of the limb. The first joint two or three times as long 



