1602 THE VOYAGE OF H.M.S. CHALLENGER. 



much narrowed ; the second joint short, the third very slender, considerably longer 

 than the fourth, and the fourth than the almost linear yet tapering fifth ; the finger 

 minute, rather like the nib of a pen. This limb, instead of being, as in the type-species, 

 " diminutive, barely exceeding the basal joint of the preceding pair," is nearly as long 

 as the whole limb in that pair. 



Pleopods. — Peduncles narrow, elongate ; coupling spines small ; cleft spine as in 

 Streetsla challengeri ; rami having about a dozen joints apiece ; the interlocking process 

 on the first joint of the outer ramus not sinuous. 



Uropods. — Peduncles of the first pair prismatic in transverse section, elongate but 

 not reaching the end of the double segment, more than twice as long as the outer, not 

 twice as long as the inner, ramus, the inner margin denticulate, the rounded apex of 

 the outer finely pectinate ; the rami prismatic, denticulate on both margins, more 

 strongly on the inner ; peduncles of the second pair as broad as but a little shorter than 

 those of the first and not reaching quite so far back, more than twice as long as the 

 rami, the inner margin slightly serrate and distally forming with the apical margin a 

 small produced triangle ; the rami similar to those of the first pair but respectively 

 shorter ; the peduncles of the third pair longer than the outer ramus, nearly as long 

 as the inner, with which the peduncle is coalesced ; the outer ramus denticulate only on 

 the inner margin, the inner on both margins, the denticulation of the inner margin being 

 continued some way up the peduncle. In the type species the first uropods are described 

 as "stouter than the second, equal in length." 



Telson between three and four times as long as broad, produced to a sharp apex 

 some way beyond the uropods ; the length more than three-fifths of that of the coalesced 

 fifth and sixth segments, equal to that of the first segment of the pleon ; there are some 

 very minute submarginal setules, and a little faint serration is visible near the middle of 

 the lateral margins. 



Length, nine-tenths of an inch. 



Locality.— Station 330, March 8, 1876 ; South Atlantic ; lat. 37° 45' S., long. 33° 0' 

 W. ; surface ; surface temperature, 64°'2. One specimen, female, with young in the 

 pouch. 



Remarks. — The specific name refers to the rigid straightness of the specimen as 

 preserved. A specimen, one-third of an inch long, probably belonging to this species, 

 was taken in Simon's Bay, Cape of Good Hope, November 10, 1873. The type 

 species of the genus was obtained in the Pacific, "lat. 2S° 06' N., long. 140° 12' W.," 

 Dr. Streets' specimen being also a female. The remarkable differences between the 

 adult, with its pointed head and tail, and the young first taken from the pouch, with 

 both ends blunt, may be seen from the figures. 



