The Fresh-wafer Entomostraca of Cape Province. 305 



of secondary denticles on the caudal claws. All the species treated of 

 in the present paper belong to the first of these groups with denticu- 

 lated caudal claws. This group again is divided by Dr. Eichard into 

 two subdivisions, according to the form of the cephalic fornix, which in 

 the one subdivision is rather prominent, terminating behind on each side 

 in a well-marked sharp corner, whereas in the second subdivision it is 

 quite simple, without any projecting corner behind. Both these sub- 

 divisions are represented in the Fauna of Cape Colony, the first five 

 species described below belonging to the former subdivision, the other 

 two species to the latter. In my opinion the form of the cephalic 

 fornix is of more essential significance than the armature of the caudal 

 claws, and accordingly I should prefer to base the primary division 

 upon this character, and to use the armature of the caudal claws in the 

 second place for distinguishing two subdivisions of the one primary 

 group. 



1. DAPHNIA MAGNA, Straus. 

 (Plate XXIX, figs. 1, 1 a, 6.) 



Daphnia magna, Straus. Mem. Mus. d'Hist. Nat. vol. vi, 1820, 

 p. 159, pi. 29, figs. 21 and 22. 



Syn. : Daphnia Schaefferi, Baird. 



Specific Characters Female. Valvular part of shell (carapace), 

 seen laterally, broadly oval in outline, with the spine originating far 

 above the axis of the body and more or less strongly upturned ; 

 denticles of dorsal edge extending about to the cervical region. 

 Cephalic part of shell (head) of moderate size and rather procumbent, 

 exhibiting on each side a well-marked arched keel running parallel to 

 the dorsal edge, and in some cases accompanied by another imperfectly 

 developed keel ; foruix strongly prominent and terminating behind in 

 a sharp corner ; dorsal margin of head evenly curved and joining the 

 almost straight ventral margin by an abrupt bend ; rostrum slightly 

 prominent, though obtuse at the tip. Eye of moderate size. Anten- 

 uulae small, but well defined and conical in form. Tail-piece rather- 

 produced and considerably attenuated distally ; posterior or dorsal edge 

 deeply sinuated beyond the middle, dividing the anal denticles into 

 two sets ; apical claws rather slender and evenly curved, with the 

 secondary denticles very delicate and densely crowded. 



Remarks. The above-characterised form is unquestionably identical 

 with the well-known European species, D. magna, though the South 

 African specimens differ a little from the typical ones in the form 

 of the head and in the more strongly upturned shell-spine. The 

 largest of the specimens examined had a length (without the shell- 



