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



22 articulations. Of these, as in the preceding form, the 2nd and 8th are con- 

 siderably larger than the others, and each apparently represents 2 coalesced 

 articulations. This seems also to be the case with the last joint, which is 

 rather longer than the next preceding ones. The antenna carries anteriorly 

 short bristles of nearly uniform length. 



The posterior antennae (fig. 5) resemble in structure those in the preceding 

 form, and, like them, have the outer ramus a little shorter than the inner. 



The mandibles and maxillae (see figs. 6, 7) are likewise of a structure 

 very similar to that in Scaphocalamts. 



The anterior maxillipeds (fig. 8), on the other hand, are distinguished by 

 the large size of the 5 apical sensory appendages, which are somewhat fusi- 

 form in shape, and strongly incurved, so as to cross the spines issuing from 

 the anterior lobes. 



The posterior maxillipeds (fig. 9) are rather feeble in structure, and, as 

 in the preceding form, have the terminal part recurved, and clothed with long, 

 slender setae. 



The natatory legs (figs. 1013), on the whole, agree in their structure 

 very closely with those in Scaphocalanus ; and, as in that form, the rami of 

 the 3 posterior pairs are provided on their posterior face with irregular trans- 

 verse rows of small spinules. 



The last pair of legs (fig. 14) are very small, and still less fully devel- 

 oped than in Scaphocalanus, each leg being composed of only 2 joints, the 

 1st representing the basal part, the 2nd the outer ramus. The latter is much 

 the larger, and is fusiform in outline, carrying 3 unequal spines, one apical 

 and 2 lateral. Of the latter, the inner one is much the largest, and rather 

 elongated, being obliquely incurved and finely spinulous on the edge. 



Occurrence. Some few female specimens of this form were found in a 

 sample taken on the 22nd May, 1894, north of the 81st degree of latitude, 

 the tow-net having been lowered to 100 metres. 



Gen. Xanthocalanus, Giesbr. 



Remarks. This genus, established by Dr. Giesbrecht, is chiefly charac- 

 terised from Scolecithrix by a somewhat different structure of the anterior 

 maxillipeds, and of the last pair of legs in both sexes. Moreover, the relative 

 length of the rami in the posterior antennas, and the mandibular palps, is 



