108 



4th pairs of legs peculiarly transformed on right side. Last pair of legs on the 

 whole resembling those in the male of H. saliens, though exhibiting some small 

 differences: right leg with the 2nd joint produced inside to a knob-like prominence, 

 the last 2 joints imperfectly defined from each other; left leg with the terminal 

 joint comparatively narrower and more elongated, exceeding in length the 2 pre- 

 ceding joints combined. 



Colour. Body generally of a dark olivaceous hue, anterior antennae and 

 caudal raini tinged with reddish brown. 



Length of adult female somewhat exceeding 3 mm. 



liiMiifirl,'*. There cannot in my opinion be any doubt that this is the 

 Cydopsina borealis originally described by Seb. Fischer, since, as shown by the 

 present author, it is the only species of Heterocope occurring in the tract from 

 which Fischer received his material. Owing to the imperfect description given 

 by that author, it was not recognized, bowever, by subsequent carcinologists, and 

 in the year 1890 it was re-described by Dr. Imhof as a new species under the 

 name of H. Weismanni. By some other authors (Nordqvist, Gruber) it was 

 confounded with H. salient, Lilljeb., to which species it certainly bears a great 

 resemblance. On a closer comparison, however, it may be easily distinguished 

 by its considerably more robust body, the comparatively shorter anterior antennae, 

 and also by some slight differences in the structure of the caudal rami and tbe 

 last pair of legs in both sexes. A character quite peculiar to the present 

 species, and not found in any other known Calanoid, has been first pointed out 

 by Dr. Gruber, viz., the peculiar transformation in the male of the outer ramus 

 on the right side of the 2nd to 4th pairs of legs. This transformation is perfectly 

 constant, and will alone suffice to distinguish the male of the present species. 



Occurrence. I have only met with this form in the eastern part of Fin- 

 mark, where it seems to be generally distributed in small tarns and ditches. It 

 occurs in this way in great abundance on the mainland opposite Vardo, as also 

 at Matsjok, an affluent to the river Tana. In habits it agrees with H. saliens, 

 moving in a similar jerky manner. 



Distribution. Siberia, in the rivers Taimyr and Boganida (Fischer), lana 

 territory, New Siberian Islands, territory of Akmolinsk (the present author), Kola 

 Peninsula and Nova Zembla (Lilljeborg), Bodensee (Imhof). 



