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 in sea-water for twenty days, and it
perfectly recovered. As this species has a thick calcareous operculum,
I removed it, and when it had formed a new membranous one, I immersed
it for fourteen days in sea-water, and it recovered and crawled away:
but more experiments are wanted on this head.
The most striking and important fact for us in regard to the
inhabitants of islands, is their affinity to those of the nearest
mainland, without being actually the same species. Numerous instances
could be given of this fact. 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
almost every product of the land and water bears the unmistakeable
stamp of the American continent. There are twenty-six land birds, and
twenty-five of these are ranked by Mr. Gould as distinct species,
supposed to have been created here; yet the close affinity of most of
these birds to American species in every character, in their habits,
gestures, and tones of voice, was manifest. So it is with the other
animals, and with nearly all the plants, as shown by Dr. Hooker in his
admirable memoir on the Flora of this archipelago. The naturalist,
looking at the inhabitants of these volcanic islands in the Pacific,
distant several hundred miles from the continent, yet feels that he is
standing on American land. Why should this be so? why should the
species which are supposed to have been created in the Galapagos
Archipelago, and nowhere else, bear so plain a stamp of affinity to
those created in 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 associated
together, which resembles closely the conditions of the South American
coast: in fact there is a considerable dissimilarity in all these
respects. On the other hand, there is a considerable degree of
resemblance in the volcanic nature of the soil, in climate, height, and
size of the islands, between the Galapagos and Cape de Verde
Archipelagos: but what an entire and absolute difference in their
inhabitants! The inhabitants of the Cape de Verde Islands are related
to those of Africa, like those of the Galapagos to America. I believe
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