998 THE VOYAGE OF H.M.S. CHALLENGES. 



short, with a spine at the apex of the hind margin ; the third joint not long, distally 

 cupdike, with a few spines along the hind margin ; the wrist long oval, equal in length 

 to the first joint, with a spinule or two on the convex front margin, and a fringe, but not a 

 dense one, of pectinate spines on the moderately convex hind margin ; the hand not 

 nearly half the length or breadth of the wrist, twice as long as broad, with five plumose 

 spines on the hind margin ; the finger broad, exclusive of the nail not much longer than 

 broad, with the nail nearly as long as the hand of which it seems to usurp the place, the 

 hinder and distal margins set round with fourteen strong but very unequal spines, 

 nine on the hind margin reaching the nail, and five on the apex at the other side of it ; 

 there are two cilia at the base of the nail. 



Second Gnathopods. — Side-plates nearly like the preceding pair, but wider above 

 than below, the setse of the inner surface not reaching the lower margin. The branchial 

 vesicles about as long as the first joint, rather narrow, widening a little below, with a 

 slight curve at the centre, uniform with the three following pairs. The limb very like 

 that of the first gnathopods, but with longer joints and the wrist slightly nan'ower ; 

 the first joint has the hind margin evenly convex ; there are many pectinate spines on 

 the lower half of the hind margin of the third joint ; the wrist is densely fringed with 

 pectinate spines of various sizes, but some of great length, along the hind margin, the 

 density of the fringe becoming less near the apex ; the hand, which is about a third the 

 length of the wrist, is fringed on the hind margin with shorter spines ; the finger is as in 

 the first gnathopods. 



First Perseopods. — Side-plates like the preceding pair. First joint of the limb 

 widening distally, with spines along the almost straight front margin, and at the lower 

 part of the rather convex hind margin ; the short second joint with a distal group of 

 spines ; the third joint triangular, and (measured from the top of the hind margin to the 

 apex of the front) neai-ly as long as the fourth joint, with four groups of spines on the 

 hind margin, and one on the decurrent apex of the front ; the fourth joint a narrow 

 oval, attached near the hind margin of the preceding joint, its own hind margin fringed 

 with pectinate spines ; the fifth joint three-quarters the length of the fourth, much 

 narrower, with six groups of spines along the hind margin, one at the apex of the front, 

 and a spinule higher up ; the finger rather broad, more than half the length of the fifth 

 joint, with pectinate edges and a very small curved nail. 



Second Peneopods. — Side-plates like those of the preceding pair. The limb missing. 



Third Penwpods. — Side-plates much deeper in front than behind, but in front not so 

 deep as the preceding plates. The limb missing. 



Fourth Perasopods. — Side-plates a little deeper in front than behind, fringed below with 

 spines. The first joint broad, not twice as long as broad, not so long as the third joint, 

 with spinules along the convex front margin, the hind margin at first a little sinuous, 

 then almost straight, the rounded apex partially overlapping the short second joint, 



