' 



98 



species. Copulative appendages with the terminal lappets rather produced, the 

 upper one somewhat larger than the lower and more obtuse at the end. 



Colour in both sexes pale yellowish, with a more or less distinct chocolate 

 tinge especially dorsally; speeks of the valves dark brown. 



Length of adult female scarcely exceeding 0.65 mm. 



Remarks. This form was recorded as early as the year 1820 by Jurine 

 as Monoculus ophthalmicus, and has subsequently been described under several 

 other specific names, as mentioned in the above-given list of synonyms. It is 

 readily recognised from the other 2 species here recorded by the very conspi- 

 cuous dark speeks, with which the valves are adorned, and which scarcely i 

 any case are wanting. 



Occurrence. The present little beautiful Ostracod is found rather com- 

 monly around Christiania in small ponds and ditches and has probably a wide 

 distribution over our country. In habits it perfectly agrees with the preceding 

 species. 



Distribution. Throughout Europe, North Africa, Siberia, North America. 



32. Cypria lacustris, G. O. Sars. 



(PI. XLV, fig. 2). 

 Cypria lacustris, G. O. Sars, Oversigt af Norges Crustaceer II, p. 54. 



Specific Characters. Female. Shell not nearly so strongly vaulted above 

 as in the preceding species, seen laterally, suboval in shape, with the greatest 

 height scarcely exceeding 8 /a of the length, dorsal margin forming a quite even 

 curve throughout, ventral margin slightly sinuated in the middle, both extremi- 

 ties rounded off; seen dorsally narrow lanceolate in outline, with the greatest 

 width scarcely exceeding Vs of the length, both extremities obtusely pointed. 

 Valves very pellucid, with the surface smooth and polished, wanting any traces 

 of the dark speeks, so conspicuous in the preceding species, hyaline borders 

 in front and behind remarkably broad. Caudal rami conspicuously more slender 

 than in that species and somewhat curved, apical claws less unequal, the distal 

 one about half the length of the ramus. 



Male, as usual, smaller than female and having the posterior part of the 

 shell broader and more deflexed. Right prehensile palp of maxillipeds rather 

 abruptly expanded at the end, but without any trace of the conical prominence 

 found in the preceding species inside the thumb, the latter simply lanceolate 

 in shape; dactylus coarser than in either of the 2 preceding species, with the 

 inner edge strongly bulging in the middle. Left palp conspicuously narrowed 



