XXVIII. CONTRIBUTIONS TO THE FAUNA 



OF YUNNAN BASED ON COLLECTIONS 



MADE BY J. COGGIN BROWN, B.Sc, 



1909-1910.' 



Part IX. Two remarkabi.e genera of freshwater 

 Gastropod Molluscs from the Lake Erh-Hai. 



By N. Annandale, D.Sc, F.A.S.B., Director, Zoological Survey 



of India, and B. Prashad, D.Sc, Offg. Director of Fisheries, 



Bengal, Bihar and Orissa. 



Numerous fossil shells from the Miocene beds of Eastern 

 Europe have been assigned (somewhat doubtfully we agree with 

 Fischer*) to the family Pleuroceratidae or Pleuroceridae, but this 

 famil}' is usually believed to be confined in a living condition 

 to North America. In the collection of molluscs made by 

 Mr. J. Coggin Brown of the Geological Survery of India in Yunnan 

 some years ago, we find numerous specimens of two species which 

 we think ma}^ find a place at least provisionally among the Pleuro- 

 ceratidae more convenienth^ than elsewhere. One of these species 

 has alread}^ been described more than once, and has been placed 

 by three different authors in three different genera of Hydrobiidae. 

 Its proper name is Fenouilia kreitneri (Neumayr). The other species 

 has not, so far as we can discover, been as yet described. It is 

 impossible to separate it genericall}^ from the living and fossil 

 Burmese and Chinese genus recently described by one of us under 

 the name Paraprososthenia. It has, however, such marked concho- 

 logical differences that we propose for its recejotion a new subgenus. 

 We have named it Paraprososthenia {Parapyrgula) coggini in allu- 

 sion to the name of its discoverer and to the Pyrgula-VikQ appear- 

 ance of the shell. 



The precise locality at which both species were found is Shan- 

 kuan at the north end of Erh-Hai. They were living on stones at 

 the edge of the lake at a spot liable to strong wave-action. 



The shells of Paraprososthenia coggini and Fenouilia kreitneri 

 are very different in shape, that of the former being elongate and 

 strictly conical, while that of the latter is trochiform. They 

 resemble one another, however, in the structure of the mouth, 

 which is pyriform with a continuous peristome and a thin, slightly 

 everted outer lip, and is slightly produced posteriorly but broadly 

 rounded anteriorly. Neumayr in 1880 placed F. kreitneri, on 



' Former papers in this series were published in Vols. V'-VII of the Records 

 of the India)! Miiseiim (1910-1912). 

 2 Man. Conchyl., p. 705(1887). 



