_158_ 



especially the posterior one, contracting abruptly. Front unarmed, as in the fe- 

 male. Urosome very slender and narrow, attaining almost half the length of the 

 anterior division, 2nd segment much the largest, anal segment very small, almost 

 obsolete. Caudal rami mobile, and generally spread to each side. Anterior an- 

 tennae very much shorter than in female, their length scarcely exceeding that of 

 the anterior division, and clothed in their proximal part with large curved, sensory 

 appendages. Oral parts transformed in a manner similar to that found in the 

 male of Pantcfdnnii* and I'.^'i/ilocnJtn/H^. Natatory legs exhibiting the characteristic 

 armature mentioned by Dr. Giesbrecbt, 2nd joint of outer ramus in 2nd to 4th 

 pairs provided on the bind face with an obliquely transverse row of extremely 

 delicate, somewhat flattened spines. Last pair of legs comparatively small and 

 but slightly asymmetrical, both legs biramous. with the inner ramus simple styli- 

 form and longer on right side, outer ramus of right leg biarticulate, of left 3- 

 articulate, terminal joint in both styliform. 



Colour not yet ascertained. Length of the specimen examined 1.60 mm. 



Remnrl-s. I am now of opinion that the form recorded from Nansen's 

 Polar Expedition as N. /om//Von//s, and subsequently redescribed in the present 

 Account under the same name, is in reality identical with Giesbrecht's species. 

 On a closer examination, I have convinced myself that the characteristic armature 

 of the natatory legs described and figured by Dr. Giesbrecht, is also present in 

 both sexes of the northern form. The transverse row of flattened spines occur- 

 ring on the hind face of the 2nd joint of the outer ramus is of such a delicate 

 nature, however, that it may easily escape attention, if the opposite face of the 

 joint be turned to the observer. The male, of which only a solitary specimen 

 has hitherto come under my notice, is so very unlike the female, that it was 

 only by the dissection of the specimen that I could with perfect certainty refer it 

 to the present species. The most striking difference is unquestionably the dis- 

 proportionate length of the anterior antennas, these being scarcely longer than 

 the anterior division of the body, whereas in the female their lenght considerably 

 exceeds that of the whole body. An analogous sexual disproportion in these 

 antennae has also been shown by Dr. Giesbrecht, however, in a few other Calanoids 

 belonging to the genera Calanns and Haloptilus. 



Occurrence. The above-described male specimen was found in a plankton- 

 sample taken by Mr. Nordgaard in the Oster Fjord from a depth of from 400 

 to 600 metres, and kindly sent to me for examination. In the same sample a few 

 female specimens also occurred. 



Distribution. Pacific Ocean, between Lat 14 N. and 4 S., at a depth 

 of 1000 4000 metres (Giesbrecht); polar basin crossed by Nansen, at 2 different 

 Stations. 



