9(38 THE VOYAGE OF H.M.S. CHALLENGEK. 



much below the side-plate, fringed with setules ; third joint longer than the fifth, much 

 longer than the fourth, with spinules and setules along both margins ; the fourth joint 

 with larger spinules, and at the hinder apex carrying a spine ; the fifth joint straight, 

 frino-ed behind with slender spines, and having a few spinules in front; finger curved, 

 acute, scarce half the length of the fifth joint, the edges finely pectinate ; a dorsal cilium 

 not far from the base of the nail. 



Second Perseopods. — Side-plates with the front margin nearly straight, ending in a 

 tooth, excavate behind, the hind margin below the excavation serrate and sloping forwards 

 to join the convex lower margin. Branchial vesicles larger than in the preceding 

 segment. The limb like that of the first perasopods. 



Third Perseopods. — Side-plates broad, bilobed, the hinder lobe rather deeper than the 

 front, its hind margin ending in a small tooth. The branchial vesicles nearly as large as 

 the first joint. The first joint pear-shaped, the front margin convex, fringed with spines, 

 the hind margin deeply serrate, the lower part straight, rounded at the lower angle ; 

 the second joint very short ; the third scarcely longer than the fourth, much shorter 

 than the fifth, its hind margin convex, decurrent, a little longer than the front, both 

 margins armed, but as in the two following joints not strongly; the finger very 

 slender, curved at the nail, not half the length of the long straight fifth joint, its 

 margins pectinate. 



Fourth Perseopods. — Side-plates with a deep hinder lobe ; the branchial vesicles con- 

 torted. The first, second, and third joints of the limb similar to those of the preceding 

 pair, but the first and third larger, the rest of the limb missing. 



Fifth Perseopods. — Side-plates small, deepest in the middle. Branchial vesicles small 

 and irregularly shaped. The limb resembling the third pair and the fourth so far as 

 observed ; the first joint larger than in the latter, the hind margin more sinuous ; the 

 third joint longer, the apical pointing of the hind margin of this and the following joint 

 here becoming conspicuous, the armature of all the joints of more considerable strength ; 

 the superiority of size over the corresponding joints of the third pair is greater in the 

 third and fourth joints than in the fifth and sixth. 



Pleopods. — Coupling spines small, with three or four lateral teeth ; there is a seti- 

 form spine close to the coupling spines, and there are also several other spines on the 

 peduncles, especially about the apex ; cleft spines five in number on the first pair, four on 

 the other two ; joints of the rami seventeen to eighteen. 



Uropods. — -Peduncles of the first pair shorter than the inner ramus, with some long 

 spines on the inner margin and apex ; the outer ramus shorter than the inner and than 

 the peduncle, both rami with pectinate edges, marginal spines, acute apices ; peduncles of 

 the second pair much shorter than the inner ramus, apically dentate ; the outer ramus as 

 long as the peduncle, the inner much longer, longer than any of the other rami, the 

 armature as in the preceding pah' ; peduncles of the third pair shorter than the rami, 



