CH. Ill] MOLLUSC A OF SEYCHELLES. 179 



of the evidence offered by spiders is emphasized by M. 

 Simon's removal of Madagascar from the Ethiopian and 

 its transference to the Oriental region l . 



The land and fresh water Mollusca are a doubtful 

 group with which to have many dealings of the present 

 kind ; they are not so reliable as many, owing to the fact 

 of their possessing a shell which has made them the 

 objects of collectors who often do no more than refer to the 

 " animal " as if it was a casual and unimportant inhabitant 

 of the shell But their evidence, so far as it can be read, 

 is not without bearings upon the problem that we are 

 now engaged in. A large proportion of the land Mollusca 

 are peculiar ; and there is, as in the West Indies, a great 

 development of the Cyclostomatidse. In this latter family 

 a genus Cyclotopsis is limited to the Mascarene islands 

 and to the Indian peninsula. In the Seychelles we have 

 Cyathopoma and Leptopoma, which are also Oriental 

 genera, and Helicina, which is almost world-wide but not 

 African. The two families to which these belong, Cyclo- 

 phoridse and Helicinidae, " must apparently," says Mr 

 Blanford, " have reached the Seychelles from the eastward, 

 for not one of them is found in Africa." 



Mr Blanford deals with the obvious suggestion that 

 the presence of these animals may be recent and due to 

 floating trees or the like. The currents however indicate 

 that the transference of such small creatures would be 

 from the Seychelles to India and not in the reverse 

 direction. Another possible method of colonisation by 

 the help of winds is not to be considered ; for it appears 

 1 Trouessart, La Geographic Zoologique, p. 210. 



122 



