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



second joint with spines in front ; the third equal in length to the next two united, 

 spined alon°- both margins ; the fourth longer than the fifth, with a few spines on the 

 maroins ; the fifth shorter than in the preceding perseopods, but otherwise similar, facing 

 backwards not forwards. 



Fourth Perseopods. — Side-plates like those of the preceding segment, but consider- 

 ably smaller. Branchial vesicles shorter than the first joint. Limb differing but 

 little from the preceding pair ; the first and third joints rather longer, the expansion 

 of the first a little slighter ; the spines on the front margin of the third, fourth, and 

 fifth joints more pronounced. 



Fifth Perseopods. — Side-plates smaller than those preceding them, but similar. 

 Branchial vesicles smaller than the preceding pair. First joint very slightly expanded 

 behind close to the base, the whole of the hind margin fringed with strong spines 

 alternating in length, the joint much exceeding the length of the third joint, instead of 

 being subequal to it as in the preceding pair ; the third joint shorter than in the 

 preceding pair ; the limb otherwise similar. 



Pleopods. — Coupling spines slender, with three or four retroverted teeth. Cleft 

 spines three in number on the first two pahs, on the third pair only two ; joints of the 

 rami numbering seventeen to eighteen. 



Uropods. — Peduncles of the first pair shorter than the rami ; outer ramus a little 

 longer than the inner, both with the margins fringed and the apices tipped with spines ; 

 peduncles of the second pair shorter than the rami, which are armed like the preceding 

 pair, the outer rather shorter than the inner ; peduncles of the third pair much shorter 

 than the rami ; the rami lanceolate, spined on both margins, the inner longer than the 

 outer, reaching rather further back than the first pair, which reach much further back 

 than the second. 



Telson elongate, cleft nearly to the base, reaching far beyond the peduncles of the 

 third uropods, a little dehiscent near the sharp spine-tipped apices, each plate bordered 

 on the outer margin with six or seven spines, and much resembling the adjacent rami 

 of the uropods. 



Length. — The specimen, in the position figured, measured, from the front of the 

 head to the back of the second pleon-segment, a fifth of an inch. 



Locality. — Station 149h, off Cumberland Bay, Kerguelen, January 29, 1874 ; 

 depth, 127 fathoms; bottom, volcanic mud. One specimen, female. Dredged (type- 

 specimen). 



Station 149d, Royal Sound, Kerguelen, . January 20, 1874; depth, 28 fathoms; 

 bottom, volcanic mud. Two smaller specimens. Dredged. 



Remarks. — The specific name is taken from the place of capture. 



In describing the subfamily Dexaminse, to which he assigns his genus Tritseta, 





