714 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxi. 



Abdomen two-jointed; joints about the same lengfth, the basal one 

 slightl}" the wider with tapering sides; anal lamina? nearly circular 

 in outline, each armed with four long, stout, and densely plumose 

 set». Anterior antennae two-jointed, joints about the same length, 

 both setiferous; posterior pair rather small, with a stout terminal 

 hook and a curved spine on the posterior margin of the basal joint. 

 No first maxilla?; second pair simple flattened spines, broadly trian- 

 gular, situated at some distance from the mouth-tube on either side, 

 and very far back, nearly opposite the mouth opening. 



Mouth-tube narrow and conical, intermediate in form, longer and 

 narrower than in (Jloiopotes and Euri/p/w/'us, but not as elongate and 

 pointed as in Alehum. Mouth opening terminal and circular, sur- 

 rounded with a heavy fringe of hairs. First maxillipeds of the usual 

 pattern; second pair enlarged, the basal joint much swollen, but show- 

 ing no sign of any protuberance or peg opposite the terminal claw. 

 This latter is slender, strongly curved, and reaches about to the center 

 of the basal joint. All the swimming legs are biramose, rami of the 

 first three pairs two-jointed, of the fourth pair rudimentar}' and appar- 

 ently one-jointed, owing to a more or less complete fusion of the 

 joints. Exopod of the first pair several times larger than the endopod, 

 with three huge plumose set* on its posterior border, which are 

 longer than the entire leg. 



There are also three good-sized terminal seta? and a large spine at 

 the outer corner. The terminal joint of the tiny endopod has also 

 three plumose setse on its posterior border and three spines at the end, 

 while the basal joint carries a single spine on its anterior margin. 

 There is also a large plumose seta on the outer margin of the basal 

 joint of the leg itself, which projects out over the ventral surface of 

 the exopod. Second legs of the usual pattern. Rami of the third 

 legs so near together that their basal joints overlap considerably. 

 Joints of the rami in the fourth legs so fully fused that they appear 

 to be one- jointed, but the arrangement of the set* shows that there 

 are really two joints in each ramus. Fifth legs entireh" lacking. 



Total length, 3.5 ram.; length of carapace, 2 mm.; of genital seg- 

 ment, 0.57 mm.; of abdomen, 0.43 mm.; width of carapace, 1.92 mm. 

 Color of preserved material yellowish brown, somewhat mottled, and 

 without any visible pigment. 



{ariommus^ cxpi^ an intensive particle; ojujua^ eye; hence large-eyed.) 



That the present species is distinct from Steenstrup and Liitken's 

 D. atlanticus is apparent from the following considerations: The 

 grooves on the dorsal surface of the carapace are arranged very differ- 

 ently, particularly around the eyes. Steenstrup and Liitken make no 

 mention of any eyes either in their description or figures, while in the 

 present species the}^ are large and prominent. 



