882 



THE VOYAGE OF H.M.S. CHALLENGER. 



The pleopocla are undeveloped, excepting the sixth pair, which is unequally biramose, 

 the outer branch being a little shorter than the telson and the inner half its length. 



Length, entire, 



of carapace, 



of rostrum, 



of pleon, . 



of dorsal tooth, 



of sixth somite of pleon, 



of telson, 



6-5 mm. (0'2 in.). 



1-5 



2-5 



5 



5 



1-3 



1-2 



Habitat. — Celebes Sea, October 1874. 



Oodeopus gibbosus, n. sp. (PI. CXLIII. figs. 3, 4). 



Carapace about one-third the length of the animal, anteriorly produced to a rostrum 

 that is half the length of the animal, smooth at the margins. Orbit defined by a small 

 point ; fronto-lateral angle stoutly pointed, lateral margin smooth, posteriorly descending 

 beyond the ventral surface of the pereion. 



Pleon having the first somite smooth and flat, the second elevated to a decided hump, 

 the third smooth and rounded, the fourth dorsally smooth, and laterally produced at the 

 posterior angles to a long and sharp tooth on each side ; the sixth somite is narrow and 

 smooth, increasing in diameter at each extremity. 



Telson (fig. 3z) nearly as long as the sixth somite, having the margins subparallel, 

 slightly wider at each extremity, the posterior being excavate in the median line and 

 frinsred with hairs, of which the smallest is towards the middle on each side of a small 

 median tooth and a larger tooth at the angles, and two small hairs on the lateral margin 

 near the base of the teeth at the angles. The hairs are all fringed with small points, but 

 the teeth are smooth. 



The ophthalmus is ovate, and projected on a narrow peduncle. 



The first pair of antennae is about half the length of the rostrum. 



The second pair of antennas supports a scaphocerite that reaches as far as the distal 

 extremity of the peduncle of the first pair, and a flagellum that is about two-thirds the 

 length of the scaphocerite. 



The appendages of the pereion are biramose so far as they are developed, but the 

 posterior two pairs are stfll in a state of gemmation. 



The pleopoda are as yet undeveloped, with the exception of the sixth pair (fig. v. v.) 

 which is unequally biramose, the outer branch reaching as far as the distal extremity of 

 the telson ; it, as well as the inner branch, is fringed with hairs on the inner and distal 

 margins, but is not armed with a tooth on the outer margin. 



