Annals <>f I In- South African Museum. 



occurring far above the middle of the piece ; marginal denticles incon- 

 spicuous, sub-marginal combs, however, well marked, and varying i n 

 number from six to ten on each side ; apical claws attached to a 

 well-marked conical prominence and rather coarse, basal denticle, 

 however, very small. 



Colour dark yellow, or corneous. 



Length of shell reaching 0'43 mm. 



Remarks. This form was recorded by King under the above name 

 at the same time as A. pulchella, and was redescribed in 1888 by the 

 present author from a specimen raised out of Australian mud. It has 

 also in recent times been observed by some other authors ; but its 

 identity has not always been recognised. Thus I have elsewhere 

 shown that the Alona miilleri of Eichard is identical with the present 

 species, and also the form recently recorded by Brady from the Victoria 

 Falls under the name of Leydigia quadridentata is unquestionably the 

 same species. I have formerly referred this form to the genus 

 Alonella, but am now of opinion that it should more properly he 

 retained in the genus Alona, as the oblique striation of the anterior 

 part of the valves is also found in some evidently genuine species 

 of Alona, for instance, in the above-described A. arcitata. 



Occurrence. This easily recognisable form developed rather abun- 

 dantly in one of my aquaria prepared with mud taken by Dr. Purcell 

 from a small grassy vley on the Cape Flats. 



Distribution. Australia, South America, Ceylon. 



GEN. 11. ALONELLA, G. O. Sars. 



Remarks. This genus was established by the present author in the 

 year 1862, to include four European species. To these there have been 

 added in recent times a number of exotic forms, especially from South 

 America; but some of these are, in reality, so deviating from the 

 European types as scarcely to be congeneric. To the fauna of Cape 

 Colony belongs one genuine species of the present genus. 



38. ALONELLA EXCISA (Fischer). 

 (Plate XL, figs. 5, 5 a.) 



Lynceus excisus, Fischer. Bull. Soc. Imp. d. uaturalistes de Moscou, 

 1854, p. 428, pt, iii, figs. 11-14. 



Specific Characters Female. Shell, seen laterally, oval subquad- 

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

 straight behind and ascending in front, posterior extremity somewhat 



