Origin of Species Variorum

membranous diaphragm over the mouth of the shell, might be floated in chinks of drifted timber across moderately wide arms of the sea. And I found that several species did in this state withstand uninjured an immersion in sea-water during seven days: one of these shells was the Helix pomatia, and after it had again hybernated I put it into sea-water for twenty days, and it perfectly recovered. During this length of time it might have been carried by a marine current, running at an average rate, to a distance of 660 geographical miles. As this Helix 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 sea-water, and it recovered and crawled away. Baron Aucapitaine has recently 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 Helix pomatia with me resisted the salt-water, that not one out of fifty-four specimens belonging to four species of Helix tried by Aucapitaine, recovered. ↑

On the Relations of the Inhabitants of Islands to those of the nearest Mainland .

The most striking and important fact for us in regard to islands, is the affinity of their inhabitants to those of the nearest mainland, without being actually the same species. Numerous instances could be given of this law. I will give only one, that of the Galapagos Archipelago, situated under the equator, between 500 and 600 miles from the shores of South America. Here