The Naturalist on the River Amazons, subtitled "A Record of the Adventures, Habits of Animals, Sketches of Brazilian and Indian Life, and Aspects of Nature under the Equator, during Eleven Years of Travel", is an 1863 book by the British naturalist Henry Walter Bates about his expedition to the Amazon basin. Bates and his friend Alfred Russel Wallace set out to obtain new species and new evidence for evolution by natural selection, as well as exotic specimens to sell. He explored thousands of miles of the Amazon and its tributaries, and collected over 14,000 species, of which 8,000 were new to science. His observations of the coloration of butterflies led him to discover Batesian mimicry.