iQiQ-] N. Annandale & B. Prashad : Fauna of Yunnan. 421 



pointed. The cusp of the median tooth is simple and it bears 

 several large latero-basal denticulations at each side. This tooth 

 is not so high as in Fenouilia and has the base emarginate. The 

 inner lateral tooth is relativel}' broad. 



Type-species. Paraprososthenia coggini, sp. nov. 



Distributio)i. Only known from the lake Brh-Hai, Yunnan. 



In outline and general structure the shell of this subgenus 

 resembles, as we have already noted, the North American Pleuro- 

 ceratid genus Goniohasis. The size is, however, much reduced and 

 the structure of the shell more delicate. The structure of the suture 

 resembles that of Pleurocera clevatnni, vSay, shells of which we 

 have examined. 



Paraprososthenia (Parapyrgula) coggini, sp. nov. 



The shell is narrow and elongate, sharply pointed at the apex 

 and not at all expanded at the base. It is about twice as long as 



Fig. -'. — Shell of Parapvososthenia {Parapyrgula) coggiiii, sp. nov, 



broad. The shell-substance is translucent bluish white like opal- 

 glass, the periostracum pale yellow; but all the specimens exam- 

 ined are covered with a dense growth of diatoms which gives them 

 an almost furry appearance. There are 7I or 8 whorls, but the 

 terminal whorl or half-whorl is minute and slightl}^ depressed. 

 The other whorls increase gradually and evenly. The suture is 

 oblique and linear when not obliterated externally. It is sometimes 

 accompanied by a low flattened spiral ridge, which runs above it. 

 The spiral ridge on the body-whorl is narrow but slightly flattened 

 and not very prominent. The minute sculpture of the shell consists 

 of numerous longitudinal and transverse striae. On the body-whorl 

 tine longitudinal grooves are also sometimes disposed at fairly 

 regular intervals, but they are often obsolete. The mouth of the 

 shell is large, I'i-il times as long as broad and a little more than 

 ^ as long as the whole shell. Anteriorly it is rounded and a little 

 produced, while posteriori}- it has a subcanaliculate structure. 

 The callus is moderately developed, the outer lip strongly arched 



