6 G. O. Sars. 



The 11 segments of the trunk are very distinctly 

 defined, and quite simple, cylindric, without any lateral 

 expansions. 



The genital region consists, as usual, of 2 partly 

 coalesced segments, and in the female (fig. 1) is compara- 

 tively larger than in the male (fig. 2), equalling in the 

 former the length of the 2 succeeding caudal segments 

 combined. In the female it is continued ventrally into the 

 marsupial pouch, whereas in the male it carries 2 juxtaposed 

 appendages containing the outer part of the vasa deferentia. 



The tail is comparatively much shorter than in S. gracilis, 

 and in the female scarcely exceeds 1 /3 of the length of the 

 body, if the caudal rami are excluded. In the male (fig. 2), 

 it is somewhat more slender, though scarcely attaining the 

 length of the trunk. It gradually tapers distally, and has 

 the last (7th) segment rather short and obtusely produced 

 between the insertion of the caudal rami (see figs. 12, 13). 



The compound eyes (see figs. 3, 5) are very large, short 

 pyriform, with the eye-ball semiglobose in form. The simple 

 eye, or ocellus, may be faintly traced in its usual place. 



The antennulæ (ibid.) are not particularly long, scarcely 

 exceeding the width of the head, and they exhibit the usuai 

 structure. 



The antennæ, as usual, are very different in the two 

 sexes. In the female (see fig. 3), they are rather small and 

 of simple structure, blade-like, and each terminating in a 

 thin, tentaculiform lash, being moreover densely clothed 

 along the obliquely truncated distal edge, with small sensory 

 hairs. 



In the male, these antennæ (see figs. 2, 5) are much 

 more fully developed and prehensile in character, exhibiting 

 the peculiar structure characteristic of the genus. They are, 



