It is often stated that "the survival of the fittest" is not from Darwin himself. It was used from edition 5 on instead of "Natural Selection". The subtitle of the ed. had been "Preservation of Favoured Races in the Struggle for Life".
The Complete Work of Charles Darwin Online. Complete with illustrations, "On the Origin of Species", "The Zoology of the Voyage of H.M.S. Beagle" and every single publication or drawing by Charles Darwin.