CRUSTACEA MALACOSTRACA. III. 103 



broad, while the major posterior half is narrow, as second segment is even slightly more than half 

 as broad again as sixth segment, which is somewhat broader than the front end of fifth segment and 

 a little broader than fourth segment; the major portion of the lateral margins of third segment con- 

 verge exceedingly, those of fourth segment very considerably backwards, while the margins of fifth 

 segment converge a little forwards. 



Head (fig. i b) nearly four times as broad as the distance between the anterior ends of the 

 cephalic keels, and the anterior margin of the front area is nearly straight. Antennulse, as far as 



could be ascertained, have the second joint longer than the first and rather thickened towards the 

 end, which has the inner process well developed and the outer small; the process of fourth joint is 

 long, the vesicle somewhat small, pyriform. — Antennal squama small, triangular. 



Second thoracic segment seems to have only a stiff seta on the antero-lateral angles; on the 

 angles of first and third segments no setse or spines could be discovered. The ventral median part 

 of seventh and the posterior part of sixth segment much vaulted and produced into a very strong 

 and extremely long process (figs, i e and i f), which is directed downwards and somewhat backwards, 

 while its most distal, acute part is curved much backwards; in front of this process projects from the 

 anterior part of sixth segment a long, slender, acute process (fig. i e) directed vertically downwards. 

 — First pair of legs (fig. i c) very moderately robust and slightly thicker than second pair; fifth joint 

 with two setse on the lower margin, sixth joint conspicuously longer than the fifth; accessory claw 

 well developed. Second (fig. i d) to fourth pair very characteristic, as the fifth joint has on the lower 

 margin a moderately long spine at the middle, a very long, slender spine near the end, and a little 

 before the latter a long third spine; sixth joint has the distal half somewhat thick. The posterior 

 pairs distinctly more slender than the others, without natatory setae. 



Abdomen (figs, i a and i f) a little longer than broad, subtriangular, with the end somewhat 

 narrowly rounded and the lateral margins rather feebly convex. — Operculum distinctly broader than 

 long, with the posterior margin semicircular, and without any tubercle or process on the ventral sur- 

 face. — Uropods with the exopod small, considerably less than half as long as the endopod, which 

 in the young specimen is somewhat thick. 



Length of the specimen, which has seventh pair of legs only half-grown, 16 mm. 



Remarks. ^V. armatus is easily distinguished from all other species of the genus in having 

 a long, slender, straight process on sixth segment in front of the very long, strong and curved pro- 

 cess of seventh segment. The four anterior pairs of legs afford further valuable characters. Though 

 the shape of the body in the adult female may differ somewhat from that of the young specimen 

 described — probably the posterior half as the body is proportionately somewhat less narrow in the 

 adult — the features pointed out will certainly prove to be sufficient for determination. 



Occurrence. Taken by the "Ingolf" at its deepest station in the warm area. 



South of Davis Strait: Stat. 38: Lat. 59°i2' N., Long. 5i°05' W., 1870 fath., temp. 1-3°; r spec. 



