CHINA, HAINAN, FORMOSA, AND COREA 



317 



peculiar forms of fresh-water operculates, whose exact position is 

 hardly yet assured. 



Land and Fresh-ivater Mollusca of the Chinese Province 



The island of Hainan^ in the extreme south of the sub- 

 region, has 40 species of Mollusca, 22 of which are peculiar, but 

 there is no peculiar genus. 



The Mollusca of Fonnosa^ although in many cases specifically 

 distinct, show close generic relationship with those of China. 

 The characteristic Chinese groups of Helix and Clausilia occur, 

 and there is still a considerable Indian element in several species 

 of Streptaxis^ 3Iacrochlamys, Kaliella^ and Alycaeus. The oc- 

 currence of two Amphiclromus., a genus which, though Siamese, 

 is not found in China or Hainan, is remarkable. 



The peninsula of Corea must undoubtedly be included in the 

 Chinese sub-region. It is true that the land operculates scarcely 

 occur, but there are still a number of Clausilia^ and several of 

 the characteristic Chinese groups of Helix are reproduced. In 

 some points Corea appears to show more affinity to Japan than 



