iSç^No. 8. SOUTH-AFRICAN ENTOMOSTRACA. 37 



Description of the female. 



Full}- adult specimens do not even attain a length of '/a mm., and 

 this form is, accordingly, one of the smallest known Cyprididae. 



The shell is not ver\- tumid (comp. figs. 5 a & 5 b;, the width and 

 height being about equal. 



Seen laterally (fig. 5 a\ it exliibits a rather regular, rounded OA-al form, 

 being however somewhat higher behind than in front. The dorsal margin 

 is slightly arcuate, sloping gently towards the anterior extremity-, more 

 steeph' to the posterior one. The ventral margin is almost straight, without 

 any distinct median sinus. The anterior extremity appears somewhat 

 obliquely roimded, whereas the posterior one is obtusely blunted. 



Seen from above (fig. 5 b\ the shell is rather regularly oval in out- 

 line, with the greatest width occurring about the middle, and the an- 

 terior extremity a little narrower than the posterior, both being somewhat 

 blunted at the tip. 



The valves are slightly unequal, the right one being the larger and 

 overiapping the left along the anterior extremity by a hyaline border. 



The surface of the shell is perfectly smooth and polished, being only 

 sparingly clothed with delicate hairs towards each extremity. 



The structure of the several appendages, and of the caudal rami. I 

 have not been enabled to make out, but, in all probability, they do not 

 differ essentially from those in other species of the genus. 



The colour is a dark sepia, darkest around the edges and across 

 the back. 



Obsers'ations. Only a small number of specimens of this diminutive 

 species were detected in one of my aquaria, and of these I only succeeded 

 in seciuing 2 or 3 for a closer examination. In habits it agrees with the 

 other species of the genus, being enabled to swim rather quickly by the 

 aid of its long natatory setae. Only female specimens were observed : but 

 it is most probable, that male specimens were also present. 



Gen.: CypHcercus. G. O. Sars, n. 



Generic Characters. Shell narrow oblong, tumid, subameate behind. 

 \'alves slightly unequal, the left one being the larger, surface smooth. 

 Xatatorv setae of both pairs of antennæ well developed. Palp, and masti- 

 cator)' lobes of ist pair of maxillae narrow. Caudal rami exceedingly 

 large and elongated, terminating with 2 strong claws and 2 bristles. 

 Cœcal appendages of intestine unusually short, ovarial tubes, on the other 



