336 Annul* of the South African Museum. 



Specific Characters Female. Shell, seen laterally, oblong oval in 

 outline, with the dorsal margin evenly arched, ventral nearly straight, 

 hind extremity obtusely truncated. Head not much procumbent, with 

 the rostral corner moderately produced. Surface of valves sculptured 

 with somewhat distant longitudinal striae, partly anastomosing with 

 each other. Ocellus smaller than the eye, and located much nearer to 

 it than to the tip of the rostrum. Auteunulae almost extending 

 as far as the latter. Tail-piece somewhat produced, with the distal 

 part comparatively narrow and of uniform width throughout, and 

 transversely truncated, with the hind corner sub-angular ; supra-anal 

 angle rather slight, and occurring far above the middle of the piece ; 

 infra-anal denticles well marked, and gradually somewhat increasing 

 in size distally ; sub-marginal combs about nine on each side ; apical 

 claws attached to a short conical prominence and rather slender, with 

 the basal denticle of moderate size. 



Length of shell about O42 mm. 



Remarks. This form was recorded as early as the year 1852 by 

 King, and was subsequently redescribed by the present author from 

 specimens collected by Dr. Th. Whitelegge in the neighbourhood of 

 Sydney. It may easily be recognised from any of the species here 

 recorded by the shape and armature of the tail-piece. 



Occurrence. Some few specimens of this form were found in an 

 alcoholic sample procured by Dr. Purcell from a dam near Bergvliet, 

 and kindly sent to me for examination. 



Distribution. Australia. 



36. ALONA BUKOBENSIS, Welthner. 

 (Plate XL, figs. 3, 3 a.) 



Alona bulcobensis, Welthuer. Die Cladocerer Ost Africas, 1897, p. 9, 

 pi. i, figs. 16-18, 20, pi. 2, fig. .32. 



Specific CharactersFemale. Shell, seen laterally, oblong quad- 

 rangular in outline, with the dorsal margin gently arched, ventral 

 nearly straight, posterior extremity obtusely truncated, with the upper 

 corner well marked, lower rounded off. Head somewhat procumbent, 

 with the rostral corner moderately produced and obtuse at the tip. 

 Surface of valves sculptured with somewhat distant and rather faint 

 longitudinal striae, in some places anastomosing with each other. 

 Ocellus almost as large as the eye, and located nearer to it than to the 

 tip of the rostrum. Antennulae almost extending as far as the latter. 

 Tail-piece comparatively short, but rather broad and scarcely narrowed 

 distally, infero-posteal corner evenly rounded off ; supra-anal angle 



