[6] The large claws or pincers of some of these crabs are most
beautifully adapted, when drawn back, to form an operculum to the
shell, nearly as perfect as the proper one originally belonging to the
molluscous animal. I was assured, and as far as my observations went I
found it so, that certain species of the hermit-crab always use certain
species of shells.
[7] Some natives carried by Kotzebue to Kamtschatka collected stones to
take back to their country.
[8] See Proceedings of Zoological Society, 1832, p. 17.
[9] Tyerman and Bennett. Voyage, etc. vol. ii. p. 33.
[10] I exclude, of course, some soil which has been imported here in
vessels from Malacca and Java, and likewise, some small fragments of
pumice, drifted here by the waves. The one block of greenstone,
moreover, on the northern island must be excepted.
[11] These were first read before the Geological Society in May, 1837,
and have since been developed in a separate volume on the "Structure
and Distribution of Coral Reefs."
[12] It is remarkable that Mr. Lyell, even in the first edition of his
"Principles of Geology," inferred that the amount of subsidence in the
Pacific must have exceeded that of elevation, from the area of land
being very small relatively to the agents there tending to form it,
namely, the growth of coral and volcanic action.
[13] It has been highly satisfactory to me to find the following
passage in a pamphlet by Mr. Couthouy, one of the naturalists in the
great Antarctic Expedition of the United States:--"Having personally
examined a large number of coral-islands and resided eight months among
the volcanic class having shore and partially encircling reefs. I may
be permitted to state that my own observations have impressed a
conviction of the correctness of the theory of Mr. Darwin."--The
naturalists, however, of this expedition differ with me on some points
respecting coral formations.
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