436 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



like Norvcgicus, wliile the sculpture of the distal souiites of the abdo- 

 men is more like spinosua. 



The dorsal carina of the carapax is armed with three spines, and 

 usually a smaller fourth one in front of the others and just back of the 

 l^ase of the rostrum ; the subdorsal carina is armed with two spines, as 

 in Worvegicus, and. often with a rudiment of a third behind these; the 

 lateral carina does not extend back of the middle of the carapax, and is 

 armed with a single spine, as in Norvegicus. There are no distinct car- 

 in£e on the first four somites of the abdomen, but the fifth somite is flat- 

 tened above and has subdorsal carinre slightly diverging posteriori^', and 

 below these, each side, another carina, nearly ijarallel with the subdor- 

 sal; and the sixth somite is flattened above and subdorsally carinated, 

 as in sjnnosus^ though the carinoe are not quite as conspicuous on either 

 somite as in that species. 



The eyes, antennulcie, and antennae are very nearly as in P. spinosus. 

 The external maxillipeds reach a little beyond the tips of the clielipeds, 

 the penultimate segment reaches nearly to the tip of the antennal scale, 

 and the ultimate segment is a little less than twice as long as the penul- 

 timate, while in P. Norvegicus it is about once and a half as long, and in 

 P. spinosus much more than twice as long, as the the penultimate seg- 

 ment. The thoracic legs differ scarcely at all from those of P. spinosus. 



The lamellflB of the uropods are very nearly as in P. spinosus. The 

 inner lamella reaches nearly or quite to the tip of the telson, is lanceo- 

 late, and six or seven times as long as broad ; the outer lamella is about 

 a tenth shorter than the inner and about four times as long as broad. 

 The telson is once and a fourth to once and two-fifths as long as the 

 sixth somite of the abdomen, is verj^ narrow, slightly acuminate, and 

 has a very narrow and acutely triangular tip, armed with only two very 

 long, slender, and i)lumose setse, which arise near together from the 

 under side. 



This species appears to be much smaller than either Norvegicus or 

 spinosus. The following measurements are from two of the larger speci- 

 mens : 



Length from tip of rostrum to end of telson 



Ijength of carapax along dorsum 



Length of rostrum in front of tho back of the orbit. 



Breadth of carapax at anteiior margin 



Greatest breadtb of carapax 



Length of sixth somite of abdomen 



Breadth of the same in the middle 



Length of telson 



Length of antennal scale 



Stations 865 to 867, 870 to 874, 877, 878; 65 to 155 fathoms. At most 

 of these stations it was taken in great abundance. 



