The presence of an operculum seems to have been of importance, as out of twelve specimens of Cyclostoma elegans, which is 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.
ON THE RELATIONS OF THE INHABITANTS OF ISLANDS TO THOSE OF THE NEAREST MAINLAND.
The most striking and important fact for us is the affinity of the species which inhabit islands to those of the nearest mainland, without being actually the same.

Numerous instances could be given.

The Galapagos Archipelago, situated under the equator, lies at a distance of between 500 and 600 miles from the shores of South America.