1 895- ^'o. 8. SOUTH-AFRICAN EXTOMOSTRACA. 41 



Observations. This peculiar form developed rather plentifully in 

 one of my aquaria, and was successfully domesticated during 2 successive 

 seasons. Male and female specimens occurred nearly in equal numbers, and 

 were often seen in copulation. It is a very active animal, swimming about 

 rather rapidly, though in some instances, as with other Cyprididae, creeping 

 slowlv on the bottom or up the walls of the aquarium in search of food. 

 In its powerfully developed caudal rami it has a very effective locomo- 

 torv apparatus, being enabled, by suddenly extending them from the 

 shell, to make extremely rapid jerks, so that it is only with great difti- 

 culty it can be caught by the aid of a dipping tube. 



Gen.: Cypt^idops^is, Brady. 



t6. Cypridopsis viduella, G. O. Sars, n. sp. 

 Ti. 6, fig. 2. a— b}. 



Specific Characters. Shell not very tumid, being scarcely wider than 

 it is high: — seen laterally, rounded oval, dorsal margin strongly curved 

 in the middle, ventral nearly straight, anterior extremity evenly rounded, 

 posterior somewhat broader and blunted: — seen from above, regularly 

 ovate, anterior extremity more pointed than the posterior. \'alves but 

 slightly unequal, smooth, clothed with delicate hairs, more crowded at 

 each extremity. Colour whitish, variegated with bluish green irregular 

 patches and dots, which do not form any distinct transversal bands. 

 Length of adult female 0,58 mm. 



Remarks. This small species is chiefly distinguished from those 

 earlier known by the comparatively less tumid shell, and by its different 

 colouring. 



Description of the female. 



Fully adult specimens but little exceed V2 nim. in length, and this 

 form, accordingly, belongs to the smaller species of the genus. 



The shell {comp, figs 2 a & 2 b"^ is comparatively less tumid than 

 jn most other species, the greatest width not exceeding the height 



Seen laterally fig. 2 a\ it exhibits a somewhat irregular, rounded 

 oval form, with the greatest height a little in front of the middle. The 

 dorsal margin exhibits, somewhat behind the ocular region, a strong, almost 

 angular curve, from which it slopes, with an almost straight course, both 

 anteriorly and posteriorly. The ventral margin, is nearly straight, the 

 median sinus being indistinct. The anterior extremity is evenlv rounded, 



