24 G. O. Sars. 



arrangement of the dark patches, with which it is orna- 

 mented. It is also rather inferior in size. 



Occurrence.- — Found in the same aquaria, in which 

 C. vittata developed. 



Gen. Hemieypris, G. O. Sars, n. 



Generic Characters. — Shell rounded or oval in form, 

 moderatel}'' tumid, somewhat resembling that in the genus 

 Cyprinotus. Right valve, however, the larger and over- 

 lapping the left to a more or less extent. Free edges of 

 left valve minutely tubercular throughout. Eye compara- 

 tivelj^ large. Natatory setæ of inferior antennæ well devel- 

 oped, reaching beyond the apical claws. Masticatory lobes 

 of 1st pair of maxillæ very short, palp robust, with the 

 distal joint quadrate in form, and armed at the tip with 

 5 comparatively short and curved claw-like spines. Second 

 pair of maxillæ without anj^ trace of a vibratory plate. 

 Caudal rami comparatively small, sublinear in form, seta 

 of dorsal edge longer than the apical one. Propagation ex- 

 clusively parthenogenetical. 



Remarks. — This new genus, it is true, in some res- 

 pects recalls that of Cyprinotus Brady. On a closer compa- 

 rison, however, it is found to differ very essentially in the 

 fact, that the unequality of the valves is entirely the reverse 

 of that characteristic of the said genus. Moreover the 2nd 

 pair of maxillæ are devoid of the vibratory plate present 

 in most other Cyprididce. Another distinguishing character, 

 as compared with Cyprinotus, is the exclusively partheno- 

 genetical propagation, no males existijig at all, whereas in 

 the species of Cyprinotus males are almost as frequent as 



