CRUSTACEA MALACOSTRACA. III. IO i 



slender, yet decidedly stronger than the other pairs (fig. 6e); all pairs with very few spines, while the 

 accessory claw is moderately developed on first pair, but somewhat robust on the other pairs; natatory 

 setae wanting. 



Abdomen (fig. 6f) as long as broad and posteriorly a little produced, with the result that the 

 end is somewhat narrowly rounded, and the parts of the margins a little before the end are straight 

 or slightly concave. — Operculum a little longer than broad, with the proximal half of the ventral 

 surface much vaulted, but without any tubercle or process; the posterior margin is convex. — Uro- 

 pods somewhat large; peduncle oblong; eudopod somewhat robust and twice, or more than twice, as 

 long as the slender exopod. 



Length of a female without marsupium, but having the ovaries swollen with eggs, r6 mm. 



Male. Body about four times as long as broad; first thoracic segment (fig. 6a) at least as 

 broad as the second, and almost or fully half as broad again as seventh segment, which is conspi- 

 cuously broader than the front end of fifth segment. 



Head five to five and a half times as broad as the distance between the anterior ends of the 

 cephalic keels, and the anterior margin of the front area is a little concave. — Antennulee as in the 

 female. — Antennae (fig. 6a) not reaching the posterior angle of fourth thoracic segment; fifth pedun- 

 cular joint proportionately longer and conspicuously thicker than in the female, sixth joint slightly 

 longer than the fifth and gradually thicker towards the end; flagellum nearly as long as sixth joint, 

 somewhat fusiform and thickest at the end of the proximal third, uujointed excepting the terminal 

 slender part, which is marked off as a joint; squama as in the female. 



Antero-lateral angles of the three anterior segments with setae as in the female; the ventral 

 protuberance of seventh segment nearly as in the female, excepting that the process is still longer. — 

 Legs as in the female; no natatory setae on the posterior pairs. 



Abdomen (fig. 6 g) shaped as in the female. — Operculum a little longer than broad; the median 

 lamella broad, moderately tapering and slightly widened at the end; the posterior margin of each 

 pleopod somewhat sinuate, and the postero-lateral margin not produced. - - Uropods as in the female. 



Length 12 mm. 



Remarks. According to the specimens to hand S. plebejus must be a small species. It differs 

 from all preceding forms and agrees with N. crassipcs n. sp., A', minutus n. sp. and N. armatus n. sp. 

 in possessing a large, curved, acute process on the vaulted ventral part of seventh thoracic segment, 

 but from these three species it is easily separated by the characters in the key (p. 90). The shape of 

 the body, no spines on the antero-lateral angles of any of the three anterior thoracic segments, and 

 the uropods, afford other good characters. 



Occurrence. Taken by the "Ingolf' at a single station in the warm area. 



South-West of Iceland: Stat. 78: Lat. (xf^f N., Long. 27°52' W., 799 fath., temp. 4-5°; 7 spec. 

 (4 c?, 3 ?)• 



