THE ORIENTAL MIGRATION. 263 



especially when we examine its past history, we 

 find that its origin is extremely complex, and dates 

 back to a much more remote period than would 

 have been imagined, had we merely taken into 

 account its present range in our own continent. 

 Professor Boettger, who is the highest authority on 

 Clausilia, tells us that the genus is known from 

 the earliest deposits of the Tertiary Era. About 

 700 species are now known, and these have 

 been sub-divided by Professor Boettger and others 

 into a number of sub-genera. Some of these are 

 extinct, but the great majority are still living. 

 The sub-genus Phcedusa occurs in the eocene 

 and oligocene of Southern Europe, but it is extinct 

 as far as our continent is concerned. Close upon 

 a hundred species, however, still inhabit India, 

 the Malayan Islands, China, Ceylon, and Japan. 

 Then again, the sub-genus Laminifera occurs in the 

 oligocene and miocene of Central Europe, and 

 survives in a single species, CL Pauli> in South- 

 western France. The groups Garnieria of China, 

 Macroptyckia of East Africa, Boettgeria of Madeira, 

 and Nenia of South America, have no fossil repre- 

 sentatives. We have here some very remarkable 

 cases of discontinuous distribution which testify to 

 the antiquity of the genus, and this is certainly 

 confirmed by the fossil evidence. However, it is 

 hardly likely that the headquarters, as it were, of 

 Clausilia have always been in South-eastern Europe. 

 Most of that part of the Continent has been sub- 



