There is nothing, therefore, to be derived from all the facts hitherto known, that could, in the slightest degree, give support to the opinion that the new genera which I have discovered or established among the fossil remains of animals, any more than those which have in like manner been discovered or established by other naturalists, the _palæotheria_, _anoplotheria_, _megalonyces_, _mastodonta_, _pterodactyli_, _ichthyosauri_, &c. might have been the sources of the present race of animals, which have only differed from them through the influence of time or climate. Even if it should prove true, which I am far from believing to be the case, that the fossil elephants, rhinoceroses, elks, and bears, differ no more from those at present existing, than the present races of dogs differ from one another, this would not furnish a sufficient reason for inferring the general identity of the species, because the races of dogs have been subjected to the influence of domestication, which these other animals neither did nor could experience. Farther, when I maintain that the rocky beds contain the bones of several genera, and the alluvial strata those of several species which no longer exist, I do not assert that a new creation was required for producing the species existing at the present day. I only say that they did not originally inhabit the places where we find them at present, and that they must have come from some other part of the globe. Let us suppose, for instance, that a great irruption of the sea were now to cover the continent of New Holland with a coat of sand or other debris; it would bury the carcases of animals belonging to the genera _Kangurus_, _Phascolomys_, _Dasyurus_, _Perameles_, flying phalanger, echidna, and ornithorynchus, and it would entirely destroy the species of all these genera, since none of them exist now in any other country. Were the same revolution to lay dry the numerous narrow straits which separate New Holland from the continent of Asia, it would open a road to the elephants, rhinoceroses, buffaloes, horses, camels, and tigers, and to all the other Asiatic quadrupeds, which would come to people a land where they had been previously unknown. Were some future naturalist, after having made himself well acquainted with this new race of animals, to search below the surface on which they live, he would find remains of quite a different nature.