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



The rostrum, which dips downwards a little anteriorly, is armed with sixteen spinules 

 in one specimen, and twenty in another ; all the spinules articulate excepting perhaps the 

 first two or three, and even they appear to have a line of articulation, and the posterior 

 margin of each, as well as the lobe to which it is articulated, appears to be thickened for 

 the purpose of supporting a fasciculus of small hairs. On the lower margin, not far from 

 the apex of the rostrum, stands one rigid tooth that is directed straight forwards, and 

 from this the lower margin ascends to the apex. 



The ophthalmopoda are three-fourths the length of the rostrum, and the ophthalmus 

 is comparatively large. 



The first pair of antenna? has the peduncle a little longer than the rostrum, and the 

 scaphocerite of the second pair is still longer. 



The second pair of gnathopoda reaches beyond the extremity of the rostrum but 

 falls short of that of the scaphocerite. 



The first pair of pereiopoda is long and slender, and reaches considerably beyond the 

 scaphocerite, the carpos being as long as the ischium and meros together. The second 

 pair is wanting. The third pair is damaged, being broken at the propodal joint of the 

 carpos, from which to the coxa it measures 80 mm., and therefore is nearly five times longer 

 than the entire animal. The fourth pair is broken off, but a detached limb that I take to 

 have belonged to it is correspondingly longer than the third, and resembles it in all 

 points, so far as the two can be compared, excepting that the meros of the detached leg 

 is armed with two rows of distant spines which are more conspicuous than those on the 

 attached limb. The carpos of the detached appendage is as long as the meros and half 

 the ischium. 



The anterior plate on the ventral surface of the pereion is very narrow as compared 

 with those posterior to it. 



Nematocarcinus paucidentatas, n. sp. (PI. CXXXII. fig. 9). 



Carapace one-third the length of the animal, exclusive of the rostrum and telson ; 

 anterior dorsal surface slightly carinated and horizontally produced to a laterally 

 compressed rostrum that is about one-fourth the length of the carapace, armed on the 

 upper surface with nine sharp spinules, and on the lower with one fixed tooth near the 

 apex and a fringe of cilia between. 



Pleon from the posterior half of the third somite to the telson laterally compressed. 

 Telson dorsally flattened, and the sides depressed, the longitudinal angle armed with 

 seven or eight small spinules on each side. 



