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



branchial vesicle more dilated above than belo^Y ; first joint spined on front margin, 

 hinder margin not much jjroduced downwards, but cut like that of the preceding limb, 

 forming eleven teeth, of which the first and last are the smallest, the last not reaching so 

 far down as the last but one ; the second joint and the finger as in the preceding limb ; 

 the third, fourth and fifth joints more elongate, spined on both margins ; the fifth joint 

 less expanded near the palm. 



Fifth Perseopods. — Side-plates less deep than the preceding, but of equal breadth ; 

 branchial vesicles less elongated ; first joint much more elongate, scarcely spined on front 

 margin, narrowing below, not produced far downwards, but overlapping the very short 

 second joint, the hind margin cut into fourteen teeth, the last two as in the preceding 

 perseopods ; the third joint stouter but shorter than the corresponding joint of the 

 preceding pair and than the fourth joint of its own pair ; the fourth joint long, a little 

 shorter than the fifth ; the whole limb very straight, ending in a long, slender, very 

 slightly curved finger, sharply pointed, without any trace of nail, fringed on the anterior 

 margin with a close-set row of microscopic spines bending downwards. On the third, 

 fourth and fifth joints there are various groups of spines on both margins and at the 

 lower angles, the hand and wrist being sharply indented on the front margin, the hand 

 not having a palm as in the preceding peraeopods, though its distal edge is cut into teeth, 

 apparently all round, certainly behind. 



Pleopods. — The peduncles of the three pairs, as is usually the case, decrease a little 

 in length successively backwards ; on the inside of the peduncle near the infero-anterior 

 angle are three spines, one small and simple, the other two (the coupling spines) stout 

 and large, having from four to six teeth on the distal half of the front margin pointed 

 back towards the base of the spine, and about the middle of the other margin a single 

 tooth directed forwards ; the rami have the first joints not very elongate, followed by 

 sixteen to eighteen shoit joints, all with the usual long plumose setae; the first of the 

 outer ramus has at its origin an irregularly shaped process seeming to serve the double 

 object of interlocking it with the peduncle and with the other ramus, on the first joint of 

 which there is a small corresponding process. On the inner side of the first joint of this 

 inner ramus there is also a row of five cleft spines ; they are thick at the base, plumose 

 throughout their slightly sinuous length as far as the split termination, the inner portion 

 of which is of a pointed spoon-shape, the outer and longer spiuiform, with the inner edge 

 denticulate. The cleft spines in most species are very similar to those here described, 

 but the details are seldom so easily observed as in this species. 



Uroiwds. — Peduncle of first pair longer than rami, some spines on the upper edges ; 

 rami slender, spined on the upper edges, outer ramus shorter than inner, both curving 

 inwards at the tips, both with microscopic pectination on the upper border, the pectination 

 being much stronger in the outer ramus ; peduncle of second pair shorter and less stout 

 than in the preceding pair, equal in length to the inner ramus ; rami similar to those of the 



