332 RELATIONS OF THE INHABITANTS OF [CHAP. XIH. 



operculum, I removed it, and when it had formed a new mem- 

 branous one, I again immersed it for fourteen days in sea-water, 

 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 remark- 

 able, 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 tlie 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 the distance of between 500 and 600 miles from the shores 

 of South America. Here almost every product of the land and of 

 the water bears the unmistakable stamp of the American con- 

 tinent. There are twenty-six land-birds ; of these, twenty-one, or 

 perhaps twenty-three, are ranked as distinct species, and woulc 

 commonly be assumed to have been here created; yet the clos 

 affinity of most of these birds to American species is manifest ii 

 every character, in their habits, gestures, and tones of voice, 

 it is with the other animals, and with a large proportion of the 

 plants, as shown by Dr. Hooker in his admirable Flora of tl 

 archipelago. The naturalist, looking at the inhabitants of the 

 volcanic islands in the Pacific, distant several hundred miles f ror 

 the continent, feels that he is standing on American land. W 

 should this be so ? why should the species which are supposed 

 have been created in the Galapagos Archipelago, and nowher 

 else, bear so plainly the stamp of affinity to those created it 

 America? There is nothing in the conditions of life, in the 

 geological nature of the islands, in their height or climate, or 

 in the proportions in which the several classes are associat 

 together, which closely resembles the conditions of the Soutl 

 American coast: in fact, there is a considerable dissimilarity ir 

 all these respects. On the other hand, there is a considerable 

 degree of resemblance in the volcanic nature of the soil, in the 

 climate, height, and size of the islands, between the Galapag 

 and Cape Verde Archipelagoes : but what an entire and absolut 



