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



obtuse angle where the third joint hinges on the second, and in this bent position 

 scarcely overtops the outer plates. 



First Gnathopods. — Side-plates widest at the centre, closely ciliated on the broadly 

 rounded lower margin ; first joint extending beyond the side-plate, nearly as long as the 

 next four joints united ; second joint longer than third, as long as the fourth, with two 

 sct« on the hind margin ; third joint very small, a little furred behind, with two setae 

 near the apex ; the wrist broader but shorter than the hand, slightly furred behind, with 

 two setse in front at the apex and three at the back ; the hand long, tapering, without a 

 palm, finely pectinate along the hind margin, with seta-like spines at three points on 

 that, and at two on the front margin ; finger fully half as long as the hand, with a sharp, 

 slender nail. 



Second Gnathoj)ods. — Side-plates oblong, and, like the preceding pair, furred, 

 especially on the lower margin, besides carrying some stronger cilia. The first joint as 

 long as the third, fourth, and fifth united ; the second much longer than the third, 

 subequal to the wrist ; the short third joint with very convex hinder margin, carrying 

 one cilium at a little distance from the apex ; the wrist subequal in length to the hand, 

 with six or seven scale-like cilia on the centre of the hind margin ; the hand long, oval, 

 finely furred almost all over, also with the squamose cilia on the lower two-thu'ds of the 

 hind margin, which is produced considerably beyond the front margin, forming with the 

 palm a triangular process against which the finger closes ; the finger, which is backed by 

 three or four setse, is short and stout, the hooked nail, which forms more than a third of 

 its length, not extending beyond the palm. On a diminutive scale the hand and finger 

 form a feeble chela. 



First Perwo2)ods. — Side-plates similar to those of the preceding segment, but larger. 

 The first joint broad, not reaching nearly to the end of the side-plate, shorter than the 

 fourth and fifth joints united ; third joint broad, not decurrent, much longer than the 

 fourth, not quite so long as the fifth ; the fourth joint short, hind margin straight, 

 pectinate, with a spine and two cilia at the apex; fifth joint long, slightly tapering, 

 hind margin nearly straight, pectinate, with acute spines at two points, and at the apex 

 a pair of blunt spines curving towards the edge of the finger ; the front margin of the 

 hand convex, with one or two cilia ; the finger strong, curved, with a very small dorsal 

 cilium, and one or two cilia near the nail. 



Second Perseopods. — Side-plates broader and deeper than the preceding pair, the 

 excavation behind shallow, carried far down, the margin below it taking a forward 

 direction to join the lower border, so that the upper and lower margins of the plate are 

 of equal breadth ; the joints of the limb similar to those in the preceding pair. 



Tliird Perieopods. — Side-plates very broad and deep, with the breadth and depth 

 subequal, rather deeper in front than behind. First joint irregularly rounded, two long 

 setse and a spine on the lower part of the furry front margin, the hind margin 



