120_ 



name affinis ought to be fixed, whereas the next species must bear the 

 name hirsuta. 



Occurrence. This form is rather common around Christiania in small 

 ponds and ditches, but is as a rule only met with in the early part of the 

 summer. The animals are very active, swimming about in the water rather 

 quickly. 



Distribution. Throughout Europe, North America. 



44. Cypricercus hirsutus (Fischer).. 



(PI. LV, fig. 2). 



Cypris hirsuta, Fischer, I. c. p. 159, PI. 10, figs. 68. 

 Syn: Cypris elliptica, G. O. Sars (not Baird). 

 ? Eucypris affinis-hirsuta, Aim (part). 



Specific Characters. Female. Shell conspicuously less high than in the 

 preceding species, seen laterally, oblong oval in shape, with the greatest height 

 scarcely exceeding half the length, dorsal margin gently arched, without showing 

 any gibbous bend in front, ventral margin distinctly sinuated in the middle 

 and somewhat bowed in the oral region, anterior extremity well rounded off, 

 posterior narrowed and obtuse at the end; seen dorsally, broadly oval in 

 outline, with the greatest width exceeding the height, both extremities obtuse 

 and subequal. Valves conspicuously unequal, the left overlapping the right 

 considerably along the anterior extremity; surface rather densely hairy. Nata- 

 tory setae of the posterior antennas not extending as far as the apical claws. 

 Spines of the outermost masticatory lobe of the maxillae smooth. Caudal 

 rami comparatively more slender than in the preceding species, distal claw IK 

 attaining half the length of the ramus. 



Colour dark bluish green. 



Length of adult female scarcely exceeding 1.10 mm. 



Male unknown. 



Remarks. I think I am right in identifying the above-described 

 with Cypris hirsuta of Fischer. It was formerly erroneously regarded by me 

 as identical with Cypris elliptica Baird, which has proved to belong to the 

 preceding genus (see above). Dr. Aim does not however admits its specific 

 difference from C. affinis, combining both under the name Eucypris affinis- 

 hirsuta. 1 think however that ils distinction may be found in reality to be 

 beyond doubt, as it differs from the preceding species, both in the shape of 

 the shell and in the structure of the appendages, as also very conspicuousl 

 in colour. 



