G. O. Sars. 



1. Gen. Megalocypris, G. O. Sars, n. 

 (PL 1). 



Generic Characters. — Shell large, moderately 

 tumid, of oblong reniform shape, with the dorsal margin 

 straight, ventral sinuated, anterior extremity rounded, pos- 

 terior more or less deflexed. Valves subequal, thin, pellucid, 

 without any obvious sculpturing, inner duplicatures of moder- 

 ate size, the anterior one the broader. Superior antennae 

 terminating in a fascicle of long plumous setæ; inferior 

 antennæ with the fascicle of setæ at the inferior geniculated 

 bend extremely small and without cilia. Branchial plates of 

 mandibles and maxillæ well developed. Anterior maxillæ 

 with the terminal joint of the palp rather short, quadran- 

 gular, masticatory lobes short and thick. Palp of posterior 

 maxillæ in female of usual form, in male very large and 

 distinctly cheliform, subequal in both maxillæ. Legs of the 

 usual structure. Caudal rami long and slender, with the 

 terminal claws comparatively feeble, apical seta well devel- 

 oped. Copulative organs in male large, with the terminal 

 lobe broad, triangular; ejaculatory tubes extremely small and 

 rudimentary. 



Remarks — This genus is somewhat intermediate be- 

 tween the genera Herpetocypris and Stenocypris, though differ- 

 ing from both in some points. In none of the above- 

 mentioned genera have male specimens ever been found, 

 and it is therefore very probable that the propagation in 

 both is exclusively parthenogenetical. In the present genus, 

 on the other hand, male and female specimens at all 

 times occur in about equal numbers, and the propagation is 

 accordingly pronouncedly gamogenetical. The 2 South 

 African species belonging to this genus are closely related 



