74 G. 0. SARS. CRUSTACEA. [norw. POL. EXP, 



preceding species, are rounded off. The front carries below (see fig. 3) the 

 usual small tentacular filaments. 



The tail (fig. 5) is comparatively much shorter than in the 2 preceding 

 species, scarcely exceeding Va of the length of the anterior division. It is 

 divided into 4 well-defined segments, the 1st of which, the genital segment, 

 is considerably dilated in the middle, and about the length of the 2 suc- 

 ceeding segments combined. The last, or anal segment is fully as large as 

 the preceding segment, and almost transversely truncated at the end. The 

 caudal rami are comparatively short, being scarcely twice as long as they 

 are broad, and each carry at the tip 4 plumose setae of moderate length. 

 Moreover, a very small bristle is seen issuing fi*om the inner corner of 

 each ramus. 



The anterior antennae (fig. 5) are rather slender and elongated, exten- 

 ding, when reflexed, to the end of the caudal rami. In structure, they exactly 

 agree with those in the preceding species. 



The posterior antennae (fig. 6) likewise resemble those in P. major, 

 except that the 2nd joint of the outer ramus has only a single seta at the 

 end, whereas in the 2 other species this joint carries 4 setae. 



The mandibles (fig. 7), maxillffi (fig. 8), and anterior maxillipeds (fig. 9) 

 do not exhibit any essential difference from those appendages in the other 

 2 species. 



The posterior maxillipeds (fig. 10), on the other hand, are rather more 

 produced, and have the terminal part comparatively longer, and more gener- 

 ally reflexed. 



The natatory legs (figs. 11 — 13), on the whole, agree in structure with 

 those in the 2 preceding species, though some minor differences may be found 

 to exist. Thus in the 1st pair (fig. 11), the 1st joint of the outer ramus is 

 without the usual spine outside, and the inner ramus has only 4, instead of 

 5 natatory setae. In the 3 other pairs (figs. 12 — 14) the apical spine of the 

 outer ramus is exceedingly long and slender, being much longer than the 

 terminal joint, and in the 4th pair (fig. 13) almost as long as the whole 

 ramus. As in the other species of this genus, no trace of any 5th pair is 

 present in the female. 



