has a thick calcareous operculum I removed it, and when it had formed a new membranous one, I again immersed it for fourteen days in seawater, and again it recovered and crawled away. Baron Aucapitaine has since tried similar experiments. He placed 100 land-shells, belonging to ten species, in a box pierced with holes, and immersed it for a fortnight in the sea. Out of the hundred shells twenty-seven recovered. 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 saltwater, 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.