16 HISTORY OF THE EUROPEAN FAUNA. 



fortnight in the sea. Out of the hundred shells, 

 twenty-seven recovered. The presence of an oper- 

 culum seems to have been of importance, as out of 

 twelve specimens of Cyclostoma elegans which it thus 

 furnished, eleven revived. It is remarkable, seeing 

 how well the Helix pomatia resisted with me the salt- 

 water, that not one of fifty-four specimens belonging 

 to four other species of Helix tried by Aucapitaine, 

 recovered. It is, however, not at all probable that 

 land-shells have often been thus transported ; the feet 

 of birds offer a more probable method." 



We have here positive evidence that such shells as 

 Helix pomatia and Cyclostoma elegans might easily be 

 transported to an island from the mainland. The 

 former occurs in France, Holland, and England, and 

 the latter all along western continental Europe and 

 England. And yet neither of these species inhabits the 

 Canary Islands, Madeira, or Ireland, none of which are 

 at too great a distance from Europe to be within easy 

 reach for a floating object. The fact that Cyclostoma 

 elegans does not live in Ireland is of particular interest 

 in connection with the floating-theory just quoted, as 

 on all sides of Ireland dead specimens have been picked 

 up on the shore, showing that marine currents carry 

 specimens and have thus transported them for 

 countless centuries. Nevertheless the species has not 

 established itself in Ireland. If such a fate meets a 

 land-shell of the type of Cyclostoma elegans, it may be 

 asked, with some justification, what chance slugs or 

 the smaller non-opcrculated species would have to 



