The Origin of Species by Means of Natural Selection (6th edition)

The sixth London edition, with all editions and corrections. Considered the definitive edition. the Introduction begins: "When on board H.M.S. Beagle, as naturalist, I was much struck with certain facts in the distribution of the organic beings inhabiting South America, and in the geological relations of the present to the past inhabitants of that continent. These facts, as will be seen in the lat...