26 G. O. Sars. 



from preserved specimens, and was erroneously referred to 

 the genus Cyprinotus, the author having apparently not been 

 aware of the inverse structure of the valves. It is an easilj'^ 

 recognizable species, being distinguished by the unusually 

 short and high, almost orbicular shell and the great un- 

 equalness of the valves. 



Occurrence and Habits. — In some of my aquaria 

 prepared with mud from Sumatra this form developed rather 

 plentifully, and was watched during 2 successive seasons. 

 The individuals were rather agile, swimming about rather 

 quickly, now and then affixing themselves to the walls of 

 the aquarium or to the plants growing in it. All the speci- 

 mens were of the female sex. This form was also found 

 occasionally in the sample taken by Mr. Iversen. 



D i s tr ib uti o n. — Celebes [Moniez). 



5. Hemicypris ovata, G. O. Sars, n. sp. 



(PI. Ill, figs. 2, 2 a— b). 



Specific Characters. — Female. Shell, seen laterally, 

 oval in form, greatest height not attaining | of the length 

 and occurring about in the middle, dorsal margin but slightly 

 arched, ventral almost straight, anterior extremity evenly 

 rounded, posterior obtusely truncated and somewhat broader ; 

 seen dorsally, oblong ovate in form, greatest width slightly 

 exceeding half the length and occurring behind the middle, 

 anterior extremity gradually tapered and acuminate at the 

 tip, posterior blunted. Valves rather unequal, the right one 

 overlapping the left considerably along the anterior extre- 

 mity, as also somewhat behind and below ; surface smooth 

 and slightly hairy at both extremities. Eye very conspic- 



