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



dactylos, and falls against the inner surface of the ischium, which is narrowed to 

 receive it. 



The second pair of gnathopoda (i) is very long and powerful, but only formed of four 

 joints ; the first or coxa is short, broad, and supports a small mastigobranchia (i") which 

 is somewhat rigid, sharp pointed, lies close against the joint, and is furnished near the 

 distal extremity with two small, curved, converging, pointed teeth ; the second joint is long 

 and trigonate, it is probably formed by the union of the basis and ischium, but it shows 

 no trace of an articulation, it is excavate at the base for the greater play of the oral 

 appendages. The third joint is not half the length of the second, it is smooth and 

 subcylindrical ; the fourth is nearly ecpial in length to the three preceding, gradually 

 tapers to an obtuse point, and is fringed with small spinules. 



The first pair of j)ereiopoda is moderately long and tolerably robust, the propodos being 

 about half as long again as the carpos and nearly twice the length of the dactylos, which 

 is subequal with the pollex. The second pair of pereiopoda (I) is long and considerably 

 more slender than the first pair, it has the carpos multiarticulate and much longer than 

 the rest of the limb. The first, second, third, and fourth pairs of pereiopoda carry a 

 small mastigobranchia similar to that which exists on the second pair of gnathopoda, and 

 like it without a branchial plume. The fifth pair of pereiopoda resembles the two 

 preceding, and like them terminates in a simple dactylos, but carries no mastigobranchia. 



The pleopoda are biramose, the sixth pair (v), forming part of the rhipidura, is 

 only a little longer than the telson ; the margins' are fringed with long hairs and the outer 

 plate is furnished with a short, stiff spinule at the outer angle of the diaeresis. 



From the depths at which the specimens were taken it appears that although they 

 live near the bottom they are not inhabitants of deep water. 



Nauticarisfutilirostris, n. sp. (PL CIX. fig. 1). 



Carapace about one-fourth of the length of the animal ; sides free from armature ; 

 dorsal surface carinated, crested and armed with two teeth on the frontal and gastric 

 regions, and with three beyond on the rostrum, the extremity of which is elevated, with 

 one tooth on the lower margin near the apex. 



Pleon smooth, fifth somite short, sixth nearly twice its length. 



Telson long and tapering. 



Ophthalmopoda pyriform. 



First antennas short, robust ; inner flagellum stout, outer slender. 



Second antennas as long as the animal, and furnished with a scaphocerite that is as 

 long as the first antennas. 



Second gnathopod long and robust. 



First pereiopod robust, carpos distally as wide as the propodos. 



