100 CRUSTACEA MALACOSTRACA. III. 



Second thoracic segment with small spines on the antero-lateral angles; the angles of first 

 segment with a small seta, and somewhat similar setse on the angles of third segment. Median ventral 

 part of the two posterior segments (fig. 5 f) considerably vaulted; on seventh segment is found a some- 

 what long and broad protuberance with a transverse impression (fig. 5 g) but without any acute process, 

 and it is separated by a rather deep impression from the rounded and distinctly lower protuberance 

 on sixth segment Legs moderately slender; first pair (fig. 5c) only a little thicker than second 

 pair, without any spine on fifth joint and with the accessory claw very distinct; the other pairs have 

 few and nearly setiform spines, and the accessory claw strong (figs. 5d and 56); the three posterior 

 pairs without natatory setae. 



Abdomen (figs. 5f and 5 g) a little broader than long, posteriorly broadly rounded; the posterior 

 half of the lateral margin and the entire hind margin everywhere convex, without any concave or 

 straight portion. -- Operculum a little longer than broad, with the proximal half highly vaulted, but 

 without any tubercle or process; the posterior margin straight. Uropods with peduncle short and 

 broad, the endopod considerably thicker, but only a little or slightly longer, than the exopod. 



Length of a female with marsupium 1-9 mm. 



Remarks. N. aequiremis is distinguished in having the exopod of the nropods conspicuously 

 longer in proportion to the endopod than in any other species of the genus. 



Occurrence. It has not been taken by the "Ingolf", but by the Ryder Expedition at a 

 single place. 



South of Jan Mayen : Lat. 7O32' N., Long. 8io' W., 470 fath., clay with many small stones. 2 spec. (.). 



62. Nannoniscus plebejus n. sp. 

 (PI. IX, figs.6a-6g). 



Female (without marsupium). Body a little more than three and a half times as long as broad; 

 second thoracic segment a little more than half as broad again as the seventh, and the lateral margins 

 of the fourth segment converge somewhat backwards. 



Head (fig. 6 b) a little more than four times as broad as the distance between the anterior ends 

 of the cephalic keels, and the anterior margin of the front area scarcely concave. Antennulae (fig. 6 c) 

 with first joint considerably longer than thick; second joint about as long as the first, rather thick, 

 with the outer terminal process moderately large, about as long as broad and scarcely larger than the 

 inner process; third joint distinct; the fourth moderately thick, with its process reaching beyond the 

 middle of the oblong-pyriform vesicle, which is somewhat or slightly less than twice as long as broad. 

 Antennae, judging from the length of the moderately thick fifth joint -- the sixth joint with flagellum 

 lost -- probably somewhat short; squama small, triangular, acute (fig. 6c). 



Antero-lateral margins of the three anterior segments (fig. 6 b) without spines, each terminating 

 in a somewhat small, stiff seta. The median ventral part of seventh segment (fig. 6 f) is highly vaulted, 

 forming an oblong, large protuberance, which posteriorly embraces the base of the operculum, is rounded 

 anteriorly, and a little from the front end is produced into a strong, long, curved, acute process with 

 its terminal part directed backwards. -- Thoracic legs simple; first pair (fig. 6d), though moderately 



