Darwin reached England October 2nd, 1836, and was home at Shrewsbury October 5th (according to his Letters; the 4th is the date given by Francis Darwin in the “Life and Letters”). The two years and three months which followed he describes as the most active ones he ever spent. After visiting his family, he stayed three months in Cambridge, working at his collection of rocks, writing his “Naturalist’s Voyage,” and one or two scientific papers. He then (March 7th, 1837) took lodgings in 36, Great Marlborough Street, London, where he remained until his marriage, January 29th, 1839. The apathy of scientific men--even those in charge of museums--caused him much depression, and he found great difficulty in getting specialists to work out his collections, although the botanists seem to have been keener than the zoologists. The commencement of his London residence is of the deepest interest, as the time at which he began to reflect seriously on the origin of species. Thus he says in the “Autobiography”:--“In July I opened my first note-book for facts in relation to the Origin of Species, about which I had long reflected, and never ceased working for the next twenty years.” Furthermore, his pocket-book for 1837 contained the words:--“In July opened first note-book on Transmutation of Species. Had been greatly struck from about the month of previous March” (he was then just over twenty-eight years old) “on character of South American fossils, and species on Galapagos Archipelago. These facts (especially latter) origin of all my views.” It is, perhaps, worth while to explain in greater detail the nature of this evidence which appealed so strongly to Darwin’s mind. The Edentata (sloths, ant-eaters, armadilloes, etc.) have their metropolis in South America, and in the later geological formations of this country the skeletons of gigantic extinct animals of the same order (Megatherium, Mylodon, Glyptodon, etc.) are found; and Darwin was doubtless all the more impressed by discovering such remains for himself. In his “Autobiography” he says: “During the voyage of the _Beagle_ I had been deeply impressed by discovering in the Pampean formation great fossil animals covered with armour like that on existing armadilloes;...” Darwin was thus led to conclude that there was some genetic connection between the animals which have succeeded each other in the same district; for in a theory of destructive cataclysms, followed by re-creations--or, indeed, in any theory of special creation--there seemed no adequate reason why the successive forms should belong to the same order. In his “Naturalist’s Voyage Round the World” he says, speaking of this subject: “This wonderful relationship in the same continent between the dead and the living will, I do not doubt, hereafter throw more light on the appearance of organic beings on our earth, and their disappearance from it, than any other class of facts” (p. 173 in the third edition). [Sidenote: THE GALAPAGOS.]