1076 THE VOYAGE OF H.M.S. CHALLENGER. 



nail, with two or three setules at its base, projects beyond the palm ; the dorsal cilium 

 near the base is small. 



First Perseopods. — Side-plates rather smaller than the preceding pair, with the hind 

 margin tending to convex. The first joint packed with gland-cells, almost entirely free 

 from the side-plate, in length exceeding the fourth and fifth joints united, with some 

 slender spines and spinules on the margins, of which two at the upper part of the hind 

 margin are longer than the rest, the second joint with one or two setules at the apex 

 behind ; the third joint widening distally, longer than the fourth, subequal in length to 

 the fifth, with spinules and slender spines at three points of the hind margin ; the fourth 

 joint with a spinule almost at the top of the hind margin, then a group, then two 

 separate spinules, and a large group near the apex ; there is also a group at the apex of 

 the convex front margin ; the fifth joint, tapering distally, has a spinule high up on the 

 hind margin, three near the apex, and on the convex front margin above the centre one 

 or two spinules and at the apex a small spine and a spinule ; the finger is long and 

 tapering, slightly curved, more than half the length of the fifth joint, with a small dorsal 

 cilium close to the base, and an opening within the apex. The other perseopods were 

 missing in the specimen figured, and are therefore described from a different specimen. 



Second Perseopods. — Side-plates similar to the preceding pair, but a little smaller. 

 The limb as in the first perseopods. 



Third Perseopods. — Side-plates broader than the preceding pair, the front lobe 

 nearly as deep, the hind lobe shallow. The branchial vesicles oval, longer than the 

 depth of the side-plate. The first joint elongate, wider above than below, with small 

 spines at distant unequal intervals on the margins, of which the front is rather more 

 convex than the hinder ; the second joint longer than broad, with spinules at the front 

 apex ; the third joint longer than the fourth, shorter than the fifth, with a spine at the 

 hinder apex and spinules at some other points ; the fourth joint not conspicuously 

 spined ; the fifth with spines at four or five points of the serrate front margin ; the finger 

 slender, curved, a little more than half the length of the fifth joint. 



Fourth Perseopods. — Side-plates and branchial vesicles like the preceding pair but 

 smaller. The limb very much larger than in the third perseopods, especially the third, 

 fourth, and fifth joints, and the finger much more elongate; the first joint more 

 widened at the top ; the third joint much longer than the fourth, subequal to the fifth, 

 with small spines at three or four points on the hind margin ; the fifth joint with spines 

 at six or seven points on the front margin and three on the hind margin ; the finger 

 much more than half the length of the fifth joint. 



Fifth Perseopods. — The side-plates scarcely bilobed. The limb like that of the fourth 

 perseopods but considerably longer ; the first joint more widened at the top,' the third 

 joint not very much longer than the fourth, shorter than the fifth, with spines at six or 

 seven points of the hind margin ; the nail more than half the length of the fifth joint. 



