806 



THE VOYAGE OF H.M.S. CHALLENGER. 



The third somite of the pleon is slightly arcuate at the posterior portion, and the telson 

 is slightly longer than in some species. Most of the other features are only of generic 

 value and unimportant in the determination of species. 



Nematocarcinus longirostris, n. sp. (PI. CXXXII. fig. 2). 



Rostrum slender, elevated anteriorly, and produced to a length that surpasses that of 

 the carapace ; armed on the upper surface with a large number of minute teeth and 

 spinules, from thirty-eight to forty in Dumber, of which those at the posterior extremity 

 are very minute and closely-packed articulating spinules, and those towards the anterior 

 extremity are fewer in number and more widely separated, and as they increase in size 

 they lose their articulated condition and become tooth-like in character. The under 

 surface is armed with five small rigid teeth. 



Telson subequal in length with the lateral plates of the rhipidura. 



Most of the specimens have the appendages broken off so that it is difficult to deter- 

 mine the characters further. 



Habitat. — Station 237, June 17, 1875; lat. 34° 37' N., long. 140° 32' E.; near 

 Yokohama, Japan; depth, 1875 fathoms; bottom, blue mud; bottom temperature, 35° - 3. 

 Ten specimens; three males, seven females, one bearing ova. Associated with Nemato- 

 carcinus proximatus and Nematocarcinus parvidentatus. Trawled. 



This species corresponds very closely with Nematocarcinus lanceopes, so far as can 

 be determined. Unfortunately, however, the pereiopoda are more or less broken off 

 in all the specimens, and the definition of the species must be chiefly founded on the 

 relative proportions of the body given in the above table. 



The rostrum, which has the apex broken off, is about one-third of the length of the 

 animal, and is the chief distinguishing feature of this species. It is proportionally 

 longer and more slender than in Nematocarcinus lanceopes, and carries a greater number 

 of teeth and spinules on the upper margin and fewer on the lower. 



The branchial region is defined from the cardiac and hepatic regions by a longitudinal 

 elevation external to a furrow, and from the antennal region by a similar furrow. 



The ophthalmopoda are large and pyriform, having the ophthalmus hemispherical. 





