Fresh-water Entomostraca of South America. 61 



it was identified with another of the species recorded by 

 King, viz., his Mona diaphana. The South American speci- 

 mens observed in my aquaria do not differ in any essential 

 respect from the Australian form, and I am also of opinion 

 that the Mona Davidi of Richard is the very same species. 

 As I have had at hand a very large supply of this beauti- 

 ful form, I have given figures both of the female and the 

 hitherto unknown male on the accompanying plate. The 

 largest female specimen measured 0.52 in length, and male 

 specimens 0.43 mm. 



Occurrence. — This form developed rather abun- 

 dantly in 2 of my aqnaria, both prepared with mud from 

 Argentina. 



Distribution. — If my identification of Mona Da- 

 vidi .Richard with this species is correct, its distribution in 

 America extends to Haiti. 



29. Alonella dentifera, n. sp. 



(PI. X, figs. 4, 4 a). 

 Specific Characters. — Female. Carapace 

 rather compressed, seen laterally, irregularly quadrangular, 

 greatest height considerably in front of the middle, posterior 

 extremity somewhat narrowed, and almost transversely trun- 

 cated at the end, dorsal margin boldly arched in front, 

 ventral angularly curved near the middle. Head rather pro- 

 cumbent, immobile, with the dorsal face somewhat flattened, 

 rostral projection not much produced, and obtuse- at the tip. 

 Surface of shell faintly and irregularly reticulated, lower 

 edges of valves finely ciliated, and armed at the infero-pos- 

 teal corner with 2 or 3 rather strong, blunt, dentiform projec- 

 tions. Ocellus much smaller than the eye. Lip-plate rather 



