1406 THE VOYAGE OF H.M.S. CHALLENGER. 



duced; the third joint much shorter than the fourth, having a small setule here and there ; 

 the fourth joint very much shorter but wider than the fifth, the front and apical margins 

 pectinate ; the fifth joint like the fourth slightly curved, very long, the front margin 

 pectinate ; the finger little more than a quarter as long as the fifth joint, pectinate with 

 seven or eight little teeth on the inner margin near the base. In a second specimen the 

 fourth joint showed a tolerably conspicuous spine at the apex of the front margin. 



Fourth Perieoiwds. — Branchial vesicles broader near the base than the preceding pair. 

 The first joint shorter, scarcely dilated distally, with a spine at the acute apex of the 

 front margin, and another a little higher up ; the second and third joints resemble those 

 of the preceding pair, with the front apex even more strongly produced ; the fourth joint 

 is shorter than in that pair, and the fifth joint only about half the length, so that it is 

 only a little longer than the fourth joint of its own pair ; the finger is short, curved, not 

 pectinate. 



Fifth Pera?02')ods. — The side-plates very shallow. The limb like the preceding pair, 

 but with the first joint rather shorter, having but one spine on the front margin at the 

 apex ; the fourth joint is also shorter, so that it is very little longer than the 

 third. 



Pleopods. — The coupling spines blunt-headed, with two pairs of retroverted teeth 

 below the apical pair ; the cleft spine short and stout, the two arms nearly equal, the 

 longer undilated arm showing two serrulate edges ; each ramus having ten joints. In a 

 second specimen the rami had only nine joints apiece. 



Uropods. — The first and second pairs missing, the third pair with very long peduncles, 

 of which the inner margin is apical ly produced into a short sharp point ; the inner 

 ramus not half the length of the peduncle, rather narrowly lanceolate, serrate on both 

 margins. In the dorsal view of the whole specimen, at the top of the Plate, the peduncles 

 of the third uropods are foreshortened, and for that reason do not appear to be twice the 

 length of the rami. A second specimen already referred to shows that the relative 

 dimensions are variable ; peduncles of the first pair narrower than those of the third, and 

 not longer, the rami long and slender, the outer the shorter, denticulate and finely 

 pectinate on the inner margin, the inner as long as the peduncle, pectinate on both 

 margins, denticulate on the inner and on the lower part of the outer ; peduncles of the 

 second pair shorter than those of the first, the rami bearing the same proportion to the 

 peduncle and being armed as in the first pair ; the rami of the third pair subequal, more 

 than half the length of the peduncle, ornamented as in the other two pairs. In a very 

 small specimen the rami of the third pair are quite as long as the peduncles. 



Tclson triangular, longer than broad, less than half, but more than a third of the 

 length of the peduncles of the third uropods. 



Length. — The specimen of which the full figure is given measured a quarter of an 

 inch from the front of the head to the extremity of the uropods. 



