CRUSTACEA MALACOSTRACA. III. 



9 1 



b. Anterior margin of the front area considerably less than half as long as the breadth of the 

 head. Fourth joint of the six posterior pairs of legs terminating in a long and very strong, 

 spiniform seta 14. N. affinis n. sp. 



54. Nannoniscus simplex n. sp. 

 (PI. VIII, figs.3a-.3l). 



Female. Body as to general outline nearly as in N. oblongus G. O. S. (comp. the figure of 

 Sars), from a little less to somewhat more than three times as long as broad, with second and third 

 thoracic segments not much broader than the posterior segments, and the lateral margins of fourth 

 segment converging only moderately backwards. 



Head between four times and four and a half times as broad as the distance between the 

 anterior ends of the keels limiting the front area (fig. 3 c), and the anterior margin of this area is 

 straight. — Antennulas (fig. 3d) with first joint somewhat longer than broad; second joint slightly 

 longer than the first and moderately slender, with the distal outer angle somewhat, the inner angle 

 slightly, produced; the process from fourth joint reaches at most the middle of the pyriform vesicle; 

 the foot of each of the long setse on second joint transverse. Antennal squama well marked off, very 

 oblong, acute, shorter than the diameter of third peduncular joint (fig. 3 d). 



First thoracic segment with a well developed spine on each antero-lateral angle — as in 

 the male, fig. 3 b. — angles of second and third segments with a short, stiff seta. The two posterior 

 segments with a high, broad, rounded ventral protuberance (figs. 3 k and 3 1) lying close at the front 

 margin of the abdominal operculum, and without any process. — First pair of thoracic legs (fig. 3 e) 

 not much thicker than second pair; fifth joint on the lower margin with a seta beyond the middle, 

 and at the end a long seta and a somewhat small spine; sixth joint with a spine before the middle 

 and one at the end; accessory claw thin. Second pair with about four short spines on the lower mar- 

 gin of fifth joint, and four on the sixth joint. Seventh pair (fig. 3 f) has on the lower margin of fifth 

 joint two moderately strong and two distal, long spines, three spines on sixth joint, but no natatory 

 setse on these joints; accessory claw strong. 



Abdomen (fig. 3 k) with the lateral margins distinctly, but yet rather feebly, convex, converging 

 to the somewhat narrowly rounded or subacute end. - - Operculum a little longer than broad, poster- 

 iorly rounded, on the ventral surface with a high protuberance terminating in an acute process directed 

 backwards (figs. 3k and 3 1). — Uropods with the peduncle somewhat longer than broad; endopod 

 distally thicker than at the base, and not fully twice as long as the exopod. 



Length of the largest adult specimen 26 mm. 



Male. Body a little more than three times as long as broad, with the lateral margins sub- 

 parallel (fig. 3 a). The head is about six and a half times as broad as the distance between the anterior 

 ends of the keels limiting the front area (fig. 3 b), consequently the keels converge considerably more 

 than in the females, and besides they are higher, more protruding with their ends free; the anterior 

 margin between the keels is straight. — Antennulae and proximal part of the antennae as in the female 

 (the flagella of the antennae lost). 



