123 



the middle and scarcely attaining half the length, anterior extremity gradually 

 narrowed to an acute point, posterior obtuse. Valves conspicuously unequal, 

 the left one overlapping the right in their greater extent; marginal tubercles 

 of right valve very small an densely crowded; surface of shell smooth and 

 clothed with short and delicate hairs. Anterior antennae with the terminal 

 part scarcely exceeding the basal one in length, joints successively diminishing 

 in size. Posterior antennee with the penultimate joint about equal in length 

 to 2 3 of the preceding one; natatory setae extending to the tips of the apical 

 claws. Caudal rami comparatively small, nearly straight, and gradually attenuated 

 towards the end; distal claw exceeding half the length of the ramus. 



Ground colour of the shell pale yellowish, but clouded with a number 

 of very conspicuous dark brown band-like patches, partly surrounding the 

 valves, partly extending down their sides, so as to leave 3 lighter vertical 

 areas, the middle one joining below a 4th horizontal area. 



Length of adult female 1.25 mm. 



Male unknown. 



Remarks. This form was described as early as the year 1866 by 

 Brady as a species of the genus Cypris. It is however unquestionably referable 

 to the genus Cyprinotus, in the restriction here adopted, being closely allied 

 to the southern species, C. dentaio-marginata mentioned above. When 

 examined in the fresh state, this form may be at once recognised by the 

 peculiar colouring of the shell, wich is unlike that in any of the other known 

 Ostracoda. 



Occurrence. I have met with this form in 2 localities of our country, 

 viz., at Sandviken, west of Christiania, and at Valle, on the western border 

 of Christiania Fjord. In both localities it occurred in pronouncedly brackish 

 water, and it has also elsewhere only be found under similar conditions. The 

 animals are rather active, swimming quickely about in the water. 



Distribution. Sweden (Aim), British Isles (Brady), Pommeria (Muller), 

 France (Monier). 



Specific Characters. Female. Shell very like in its general appearance 

 that of the preceding species, though comparatively less high, with the dorsal 

 margin more evenly arched and the infero-posteal corner less produced. 



47. Cyprinotus fretensis (Brady). 



(PI. LVI, fig. 2). 



Cypris fretensis, Brady & Roberlsen, Ann. Mag. Nat. Hist., Ser. IV, Vol. VI, p. 13, 



PI. IV, figs. 7-9. 



