_The Keeling Islands as Illustrating the Manner in which Oceanic Islands are Peopled._--That such causes as have been here adduced are those by which oceanic islands have been peopled, is further shown by the condition of equally remote islands which we know are of comparatively recent origin. Such are the Keeling or Cocos Islands in the Indian Ocean, situated about the same distance from Sumatra as the Galapagos from South America, but mere coral reefs, supporting abundance of cocoa-nut palms as their chief vegetation. These islands were visited by Mr. {286} Darwin, and their natural history carefully examined. The only mammals are rats, brought by a wrecked vessel and said by Mr. Waterhouse to be common English rats, "but smaller and more brightly coloured;" so that we have here an illustration of how soon a difference of race is established under a constant and uniform difference of conditions. There are no true land-birds, but there are snipes and rails, both apparently common Malayan species. Reptiles are represented by one small lizard, but no account of this is given in the _Zoology of the Voyage of the Beagle_, and we may therefore conclude that it was an introduced species. Of insects, careful collecting only produced thirteen species belonging to eight distinct orders. The only beetle was a small Elater, the Orthoptera were a Gryllus and a Blatta; and there were two flies, two ants, and two small moths, one a Diopaea which swarms everywhere in the eastern tropics in grassy places. All these insects were no doubt brought either by winds, by floating timber (which reaches the islands abundantly), or by clinging to the feathers of aquatic or wading birds; and we only require more time to introduce a greater variety of species, and a better soil and more varied vegetation, to enable them to live and multiply, in order to give these islands a fauna and flora equal to that of the Bermudas. Of wild plants there were only twenty species, belonging to nineteen genera and to no less than sixteen natural families, while all were common tropical shore plants.[62] These islands are thus evidently stocked by waifs and strays brought by the winds and waves; but their scanty vegetation is mainly due to unfavourable conditions--the barren coral rock and sand, of which they are wholly composed, together with exposure to sea-air, being suitable to a very limited number of species which soon monopolise the surface. With more variety of soil and aspect a greater variety of plants would establish themselves, and these would favour the preservation and increase of more insects, birds, and {287} other animals, as we find to be the case in many small and remote islands.[63]