The Fresh- water Entomostraca of Cape Province. 311 



some cases even prominently deflexed ; denticles of the dorsal edge 

 very small and only visible in the posterior part of the carapace. Head 

 comparatively smaller than in D. propinqua, with the front less promi- 

 nent and narrowly rounded below ; rostrum well marked and some- 

 what less deflexed than in the said species. Eye of comparatively 

 smaller size. Auteunulae about as in that species. Tail-piece some- 

 what less produced and having the hind edge straight ; anal denticles 

 about ten on each side and scarcely extending to the middle of the 

 piece ; apical claws resembling in structure those in D. propinqua. 



Length of shell reaching T8 mm. 



Remarks. In its general appearance this form is not unlike some of 

 the many varieties of D. lintijixpina, and could, therefore, easily at first 

 sight be assigned to that species. A closer examination of the tail- 

 piece, however, shows it in reality to belong to quite a different group of 

 Daphniae, viz., to the "D. pulex group." From the preceding species, 

 which belongs to the same group, it is easily distinguishable by the 

 different shape of the head and by the very thin and fragile shell-spine, 

 which latter character has suggested the specific name here proposed. 



Occurrence. Numerous specimens of this form were contained in an 

 alcoholic sample kindly sent to me by Dr. Purcell, who procured it, 

 May, 1896, from a brick-pond at Bergvliet. The present species was 

 not raised in my aquaria. 



GEN. 2. SIMOSA, Norman. 



Syn. : Simocephalus, Schoedeler. 



Remarks. As the name Simocephalus, given to this genus by 

 Schoedeler and in general use by subsequent authors, has proved to be 

 preoccupied, the above change of name was proposed in the year 1903 

 by Canon A. M. Norman. The genus originally comprised three well- 

 defined European species, viz., 8. exspinosa (de G-eer), 8. vetula 

 (Miiller), and 8. serrulata (Koch). To these there have been added 

 in recent times several other species from different parts of the world ; 

 but some of them exhibit such a close relationship to the one or the 

 other of the three said European species, that their specific validity 

 appears somewhat questionable. This may indeed apply to the three 

 South African species described below. 



8. SIMOSA AUSTRALIENSIS (Dana). 

 (Plate XXXI, figs. 3, 3 a, 6.) 



Daphnia australiensis, Dana. United States Exploring Expedition. 

 Crustacea II, 1853, p. 1271, pi. 89, figs. 4 a-e. 



