{ 375} On centres of creation see _Origin_, Ed. i. p. 352, vi. p. 499.
{ 376} In the _Journal of Researches_, Ed. 1860, p. 124, the distribution of the Bizcacha is described as limited by the river Uruguay. The case is not I think given in the _Origin_.
{ 377} In the _Origin_, Ed. i. a special section (p. 356, vi. p. 504) is devoted to _Means of Dispersal_. The much greater prominence given to this subject in the _Origin_ is partly accounted for by the author's experiments being of later date, _i.e._ 1855 (_Life and Letters_, vol. II. p. 53). The carriage of fish by whirlwinds is given in the _Origin_, Ed. i. p. 384, vi. p. 536.
{ 378} The case of islands serving as halting places is given in the _Origin_, Ed. i. p. 357, vi. p. 505. But here the evidence of this having occurred is supposed to be lost by the subsidence of the islands, not merely by the extinction of the species.
But the strongest argument against double creations may be drawn from considering the case of mammifers{ 379} in which, from their nature and from the size of their offspring, the means of distribution are more in view. There are no cases where the same species is found in _very remote_ localities, except where there is a continuous belt of land: the Arctic region perhaps offers the strongest exception, and here we know that animals are transported on icebergs{ 380}. The cases of lesser difficulty may all receive a more or less simple explanation; I will give only one instance; the nutria{ 381}, I believe, on the eastern coast of S. America live exclusively in fresh-water rivers, and I was much surprised how they could have got into rivulets, widely apart, on the coast of Patagonia; but on the opposite coast I found these quadrupeds living exclusively in the sea, and hence their migration along the Patagonian coast is not surprising. There is no case of the same mammifer being found on an island far from the coast, and on the mainland, as happens with plants{ 382}. On the idea of double creations it would be strange if the same species of several plants should have been created in Australia and Europe; and no one instance of the same species of mammifer having been created, or aboriginally existing, in two as nearly remote and equally isolated points. It is more philosophical, in such cases, as that of some plants being found in Australia and Europe, to admit that we are ignorant of the means of transport. I will allude only to one other case, namely, that of the Mydas{ 383}, an Alpine animal, found only on the distant peaks of the mountains of Java: who will pretend to deny that during the ice period of the northern and southern hemispheres, and when India is believed to have been colder, the climate might not have permitted this animal to haunt a lower country, and thus to have passed along the ridges from summit to summit? Mr Lyell has further observed that, _as in space, so in time_, there is no reason to believe that after the extinction of a species, the self-same form has ever reappeared{ 384}. I think, then, we may, notwithstanding the many cases of difficulty, conclude with some confidence that every species has been created or produced on a single point or area.