Occurrence. I have taken this form in several places, both near Chri- 

 stiania and elsewhere in the country, in small ponds and ditches with muddy 

 bottom. In habits it differs notably from the preceding species, being by far 

 not so active, as could indeed be inferred from the less fully developed nata- 

 tory setae on the posterior antenna. More generally the animals keep close to 

 the bottom, over which they are seen mowing rather slowly, very seldom 

 ascending to the surface. 



Distribution. ? Sweden (Aim), Russia (Fischer), probably also in many 

 other parts of Europe. 



45. Cypricercus obliqvus (Brady). 



(PI. LV, fig. 3). 

 Cypris obliqva, Brady, Monogr. of British Ostracoda, p. 364, PI. XXIII, figs. 3338. 



Specific Characters. Female. Shell, seen laterally, of the usual oval 

 shape, greatest height a little in front of the middle and considerably exceeding 

 half the length, dorsal margin rather boldly and evenly arched, ventral very 

 slightly sinuated in the middle and curving upwards both in front and behind, 

 both extremities rounded off, the anterior more broadly than the posterior; 

 seen dorsally, regularly ovate in outline, with the greatest width in the middle 

 and not fully attaining the height, both extremities gradually narrowed and 

 terminating in an obtuse point; end view remarkably oblique, the right valve 

 being in a higher level than the left. Natatory setae of the posterior antennae 

 extending about to the tips of the apical claws. Spines of outermost mastic- 

 atory lobe of maxillae indistinctly denticulated in their outer part. Caudal 

 rami very slender, distal claw not nearly attaining half the length of the ramus. 



Colour light greenish. 



Length of adult female amounting to 1.26 mm. 



Male unknown. 



Remarks. This form was described by Brady in his well-known Mo- 

 nograph and chiefly characterised by the peculiar oblique shape of the shell, 

 as seen from the ends. In the lateral aspect it does not look very different 

 from that of C. a/finis, though on a closer comparison some slight differences 

 may be found also in this case. The specific distinctness of this form is 

 however quite unquestionable. 



Occurrence. I have taken this form, often in great abundance, both near 

 Christiania and in several other places of our country, and always only at the 

 borders of larger lakes, never in such small ponds and ditches, which are 



15 Crustacea. 



