very actiwe little animal, svimming about in the water with great dexterity, 

 and is readily detected by its bright brownish colour. Male specimens occur 

 in nearly same number as females. 



Distribution. Sweden (Aim), British Isles (Brady) Germany (G. W. Miiller), 

 Bohemia (Va'vra), Switzerland (Kaufmann). 



,. 



27. Cyclocypris ovum, (Jurine). 



(PI. XLHI, fig. 1). 

 Monoculus ovum, Jurine, Hist, des Monocles, p. 179, PI. XIX, figs. 18, 19. 



Syn: Cypris minuta, Baird. 



loevis, G. O. Sars (not Miiller). 

 pygmcea, Cronenberg. 



Specific Characters. Female. Shell, seen laterally, rather regularly oval 

 or elliptical in shape, greatest height in the middle and scarcely attaining 2 /a 

 of the length, dorsal margin quite evenly arched, sloping however more steeply 

 behind than in front, ventral margin nearly straight, both extremities evenly 

 rounded off, the posterior somewhat more obtuse than the anterior; seen dor- 

 sally, regularly oval in outline, greatest width in the middle and about equal 

 to Va of the length, both extremities somewhat blunted. Valves only slightly 

 hairy, with the surface smooth and polished. Posterior legs with the terminal 

 joint about half the length of the penultimate one, middle apical seta com- 

 paratively small, scarcely half as long as the terminal joint, and sigmoid curved. 

 Caudal rami less produced than in C. globosa, dorsal edge exhibiting at 

 some distance from the base a few extremely small denticles, apical claws of 

 moderate size, the distal one nearly attaining half the length of the ramus. 



Male resembling the female both in size and in the shape of the shell, 

 but exhibiting the usual sexual differences. 



Colour of both sexes a more or less bright chestnut brown. 



Length of adult female scarcely exceeding 0.50 mm. 



Remarks. The identity of the above-described form with Jurine's Mono- 

 culus ovum seems to me to be beyond doubt. This species has however by 

 several authors, and also by myself been formerly recorded under the name applied 

 here to the next species, and in some cases quite new specific names have 

 been introduced. It is one of our smallest fresh-water Ostracoda, and the name 

 applied to it by Baird and Cronenberg allude indeed herto. 



Occurrence. I have met with this small Ostracod rather abundantly i 

 many places around Christiania, and it is most probably distributed over the 



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