In November 1832, Darwin returned to Monte Video, from a long journey in the interior of the South American Continent, bringing with him many zoological specimens and a great quantity of fossil bones, teeth and scales, dug out by him with infinite toil from the red mud of the Pampas--these fossils evidently belonging to the geological period that immediately preceded that of the existing creation. The living animals represented in his collection were all obviously very distinct from those of Europe--consisting of curious sloths, anteaters, and armadilloes--the so-called 'Edentata' of naturalists. And when young Darwin came to examine and compare his _fossil_ bones, teeth and scales he found that they too must have belonged to animals (megatherium, mylodon, glyptodon, etc.) quite distinct from but of strikingly similar structure to those now living in South America. What could be the meaning of this wonderful analogy? If Cuvier and his fellow Catastrophists were correct in their view that, at each 'revolution' taking place on the earth's surface, the whole batch of plants and animals was swept out of existence, and the world was restocked with a 'new creation,' why should the brand-new forms, at any particular locality, have such a 'ghost-like' resemblance to those that had gone before? It is interesting to note that, just at the same time, a similar discovery was made with respect to Australia. In caves in that country, a number of bones were found which, though evidently belonging to 'extinct' animals, yet must have belonged to forms resembling the kangaroos and other 'pouched animals' (marsupials) now so distinctive of that continent. But of this fact Darwin was not aware until after his return to England in 1836. Among the objects sent from home, which awaited Darwin on his return to Monte Video, was the second volume of Lyell's _Principles_, then newly published; this book, while rejecting Lamarckism, was crowded with facts and observations concerning variation, hybridism, the struggle for existence, and many other questions bearing on the great problem of the origin of species. I think there can be no doubt that from this time Darwin came to regard the question of species with an interest he had never felt before. It is of course not suggested that, at this early date, Darwin had formed any definite ideas as to the _mode_ in which new species might possibly arise from pre-existing ones or even that he had been converted to a belief in evolution. Indeed in 1877 he wrote 'When I was on board the _Beagle_ I believed in the permanence of species' yet he adds 'but as far as I can remember _vague doubts_ occasionally flitted across my mind.' Such 'vague doubts' could scarcely have failed to have arisen when, as happened during all his journeys from north to south of the South American Continent, he found the same curious correspondence between existing and late fossil forms of life again and again illustrated.