1276 THE VOYAGE OF H.M.S. CHALLENGER. 



length, of prismatic section like the upper antennae, its three sharp edges serrate, the 

 hinder one forming the strongest teeth ; the front margin is produced into a thin pointed 

 process, which in most of the specimens is broken or crumpled ; the second joint is very 

 small, serving as a hinge between the somewhat expanded end of the first joint and the 

 base of the third which folds back closely against it ; the third joint is rather shorter than 

 the fourth ; these two together reach back beyond the first joint when folded against 

 it, but the first joint including its distal process almost equals or occasionally exceeds 

 their united length ; the fifth joint is slender, and no doubt owing to its feeble 

 structure, the great length of the limb, and the prominent position which it appears to 

 assume, this joint is in many instances damaged ; its length is less than half that of the 

 fourth joint, its front margin being like that of the third and fourth joints very faintly 

 serrulate ; the finger curved, minute, with bulbous base, apically slender. 



Fourth Perseopods. — The first joint longer than in the first and second perasopods, 

 which this pair in many respects resembles ; the second joint small, but larger than in 

 the third pair; the third joint longer than the fourth; the fourth a little longer than 

 the fifth ; the fifth a Uttle narrower than the fourth, but wider than the corresponding 

 joint in the first and second perseopods. 



Fifth Perseopods slender ; the first joint shorter than in the preceding pair, widest 

 near the base ; the second small, a little longer than broad ; the third longer than the 

 fourth or fifth ; the fourth a good deal shorter and a little wider than the fifth; the 

 finger very slender, curved, not half the length of the fifth joint. 



Pleopods. — The coupling-spines short, with two rows of retroverted teeth and a 

 bent apex ; the cleft spine is short, the arm with the backward serratures being scarcely, 

 if at all, longer than that with the subapical dilatation ; the joints of the inner ramus 

 number from seven to nine, of the outer from nine to eleven, the inner ramus being 

 rather the shorter. 



Uropods. — The first pair reach beyond the second and as far as the apices of the 

 first or nearly so ; on the straight inner margin they have some small distant teeth, on 

 the more convex outer margin the dentation is coarser and continuous, especially along 

 the lower half till near the acute apex ;. an interruption near the middle of the outer 

 margin is occupied by a spine-like rudiment of an outer ramus ; the second pair reach 

 beyond the outer ramus of the third pair, the straight inner margin for most of its 

 length ornamented with little teeth at intervals, the spaces between being filled with 

 a succession of much smaller teeth of great slenderness ; the outer margin is interrupted 

 near the middle, about on a level with the interruption in the first pair, and there carries 

 a similar spine-like rudiment of an outer ramus, which may be regarded as marking the 

 commencement of the coalesced inner ramus ; the third pair at about the middle has a 

 free outer ramus, reaching about halfway to the end, and having its inner margin finely 

 toothed ; the outer margin of the coalesced ramus is more coarsely toothed. 



