l895- No. 8. SOUTH-AFRICAN ENTOMOSTRACA. II 



The alimentary tube (see fig. i) forms only a slight curve within the 

 dorsal part of the head, and the cœcal appendages are also considerably 

 smaller and less llcxuous than in the 2 preceding species. 



The ova in the matrix are comparatively large, and accordingly less 

 numerous than in the 2 preceding species. They are, when recently re- 

 ceived from the ovaries, of a pale greenish colour, with a large hyaline 

 central oil-globule. 



The ephippium (see fig. 6) differs conspicuously from that in the 2 pre- 

 ceding species, exhibiting a similar appearance to that of the European form 

 D. pulex. As in that .species, it causes a slight deformity of the upper 

 part of the carapace, especially prominent shordy after tlie ephippium has 

 been detached. Seen from the side, it exhibits an oval triangular form, 

 being transversely truncated in front and gradually narrowed posteriorly, 

 where it projects into a pointed process. The latter is nothing less than 

 the spine of the carapace, which remains in connexion with the ephippiiun, 

 when it is detached. The egg-ampullæ' are, as is in D. pulcx, trans- 

 versely disposed. The colour of the ephippium becomes at last very 

 dark, almost black. 



The adult male (fig. 7) scarcely attains a length of i mm., and 

 differs from the female in the usual manner, the carapace being much nar- 

 rower, oblong, with the dorsal margin nearly straight, and the head with- 

 out the rostral projection. The spine of the carapace is comparatively 

 more fully developed than in the female, and slightly upturned. More- 

 over the free edges of the valves are anteriorly fringed with delicate cilia, 

 and exhibit in front a distinctly projecting corner. 



The antennulae (fig. 8) are freely mobile, though not very large, with 

 the flagellum well developed and terminating in a somewhat hooked 

 point. 



The ist pair of legs are, as usual, modified to grasping organs, each 

 being provided with an anteriorly curving claw, and terminating in a 

 long seta. 



The tail does not exhibit any trace of a dorsal process, and has the 

 terminal part but little different from that in the female. 



The body, in both sexes, is highly pellucid and almost colourless. 



Observations. This Daphnia developed in great numbers in one of 

 my aquaria, and continued to live and propagate during the whole summer, 

 at last filling the aquarium with myriads of individuals. Male speci- 

 mens were however, as usual, rather scarce, and only occurred at the 

 close of the season. In habits, this form perfectly agrees with the northern 

 species D. pulex. 



