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



narrower, and not bulging near the base ; the third joint narrower than in the preceding 

 pair, carrying only four or five setse ; the wrist narrow, elongate, almost as long as the 

 first joint, distally scarcely widened, with five small setae on the gently curved front 

 margin, and an apical group, the hind margin carrying twelve spaced groups of spines on 

 the outer surface, and a smaller number on the inner surface, besides rows of spinules ; 

 the hand, though not half the length of the wrist, is much longer than in the preceding 

 pair, more slender, very little widened distally, in the armature closely agreeing with the 

 other gnathopods, the great palmar spine on one of the hands having seven marginal 

 teeth, on the other only five. 



First Perseopods. — The side-plates much broader than deep, the front margin sloping 

 forwards, making an acute angle with the long and nearly straight lower margin ; behind 

 the plates are very broadly excavate so as to entirely overlap tlie following side-plates ; 

 the hind margin below the excavation is straight, serrate, making almost a right angle 

 with the lower margin. Marsupial plates long and slender, with very long apical setag. 

 The limb, like the rest of the perseopods, is long and slender ; the first joint reaching 

 much beyond the side-plate, equal in length to the fourth and fifth joints united, the 

 margins carrying some long plumose setae ; the second joint short, the third shorter than 

 the fourth or fifth, scarcely decurrent, with a curved slender spine at the hinder apex and 

 two sn:ialler spines on the hind margin, and two on the front ; the fourth joint rather 

 longer than the fifth, with seven spines on the hind margin, of which the apical one 

 is very long and curved ; the fifth joint straight, with mixed spines on the hind 

 margin, the apical one close to the finger, strong and long, with serrate edges ; at the 

 front apex is a fan of eight or nine curved spines ; the finger is slender, more than half 

 the length of the fifth joint, the proximal part not so long as the adjacent apical spine of 

 the fifth joint, with a strong dorsal cilium near the base ; the nail almost as long as the 

 proximal part of the finger, with two small cilia at its base on the inner margin. 



Second Perseopods. — Side-plates very small, excavate behind, with a short straight 

 margin below the excavation, while the remaining margin, which is perhaps front and 

 lower combined, is convex. The marsupial plates and the limb as in the preceding pair. 



TJiird Perseopods. — First joint of the limb almost circular, with five stout spines on 

 the lower half of the front margin, the hinder margin except at the upper part deej^ly 

 serrate, the hind margin of the inner surface within the wing is straight and distinct ; 

 the second joint short; the third much shorter than the fourth, with four spines on the 

 front margin and an apical group, three on the hind margin and a group on its slightly 

 decurrent apex ; the fourth joint has spines at seven points in front and at six behind. 

 The rest of the limb missing. 



Fourth Perieopods. — The first joint similar in general character and armature to 

 that of the third perteopods, but much larger, longer than broad, the hind margin more 

 overlapping the second joint ; the third and fourth joints also much longer than in the 



