56 G. O. SARS. CRUSTACEA. [NORW. POL. EXP. 



The last pair of legs (fig. 10) consist each of a distinctly 3-articulate 

 stem, the 1st joint of which is united with that of the other side to a com- 

 mon basal part. The 2nd joint is much narrower and, like the 1st, quite 

 smooth. The 3rd joint is considerably longer, but very narrow in its proximal 

 part, slightly expanding towards the end, so as to assume a narrow spatulate 

 form. It terminates in 4 short digitiform processes finely denticulated at the 

 edges. Of these, the outermost is distinctly defined at the base, whereas the 

 other 3 form immediate prolongations of the joint. 



Description of the Adult Male. 



The length of the body scarcely exceeds 2'50 mm., and the male is accord- 

 ingly somewhat inferior in size to the female. 



The sexual differences are very conspicuous, though not developed to nearly 

 such a degree as in the male of Scaphocalanus ; and it is, indeed, in this 

 instance, not difficult to recognize the specific relation of the* male individuals. 



The form of the body (see PI. XII, fig 3) is, on the whole, still more 

 slender than in the female, and the relative proportions of the 2 chief divisions 

 are somewhat different, the tail being exceedingly slender, and considerably 

 more than half as long as the anterior division. The latter is of a regular 

 oblong oval form similar to that in the female, though somewhat narrower, 

 and has the lateral corners of the last segment much shorter. The tail is 

 narrow cylindric in form, and is divided into 5 segments, the 1st of which 

 is quite short, and greatly constricted at the base. The last segment, as in 

 the female, is very short, and the caudal rami with their setae do not exhibit 

 any perceptible difference from those in the female. 



The anterior antennae (fig. 7) are comparatively somewhat more slender 

 than in the female, and, when reflexed, project far beyond the limits of the 

 anterior division, extending to about the middle of the tail. The 2 antenna? 

 are exactly alike, and both are found to have one articulation less than in 

 the female, on account of the 9th being coalesced with the 8th. In addition 

 to the usual bristles, the antennae carry a number of rather fully developed 

 sensory filaments, which are especially thickly set in the proximal part of 

 the antenna. 



The posterior antennae, oral parts, and natatory legs do not exhibit in 

 their structure any appreciable difference from those organs in the female. 



