586 



THE VOYAGE OF H.M.S. CHALLENGER. 



Latreutes unidentatus, n. sp. (PL LXXXIX. fig. 6). 



Robust. Carapace armed with one large tooth on the gastric region, and anteriorly 

 produced to a rostrum that is nearly as deep as the carapace, pointed in front, and 

 having the margin serrate above with eight teeth, and below with five. 



The pleon is smooth and the telson is as long as the sixth somite. 



Habitat. — Off Sibago, Samboangan, Philippine Islands, October 23, 1873. Asso- 

 ciated with the preceding species. 



The animal is not so robust as Latreutes planus but more so than Latreutes 

 ensiferus. 



The dorsal surface of the carapace is flattened, and armed with a strong tooth over 

 the gastric region, whence the frontal margin projects to a rostrum that is nearly as 

 long and as deep as the carapace. The serrature on the upper surface reaches about 

 halfway between the apex and base, and is formed by eight small teeth, and the lower 

 margin by five ; the apical tooth being sharp and prominent. The pleon is dorsally 

 smooth, and has no tooth on the posterior margin of the sixth somite, which is shorter 

 than in the preceding species, and has the telson subequal in length with it. 



The ophthalmopoda are moderately robust, but longer than in the preceding species, 

 and do not carry a projecting tooth upon the inner surface, but are perfectly smooth. 

 The first pair of antennas is robust, and does not reach beyond the apex of the rostrum ; 

 the first joint of the peduncle is subecpaal with the ophthalmopod, the second and third 

 are shorter and subequal in length, and the inner flagellum, which is robust and tapering, 

 reaches as far as the apex of the rostrum, and supports a series of fasciculi of membranous 

 cilia. The second pair of antennas is broken off at the extremity of the peduncle, and 

 supports a slender pointed scaphocerite that is nearly as long as the rostrum. 



The oral appendages of this species have not been separately examined. 



The second pair of gnathopoda is robust and powerful, smooth on the lower surface, 

 arcuate and firm, with rows of hairs on the upper, and terminates in an acute point. 



The first pair of pereiopoda is short and robust, the second long and slender, the 

 dactylos and pollex being subequal and fringed with fasciculi of hairs. The posterior 

 three pairs correspond with those of Latreutes planus. 



