In the autumn of 1847 Mr. A. R. Wallace, who has since acquired wide fame in connection with the Darwinian theory of Natural Selection, proposed to me a joint expedition to the river Amazons, for the purpose of exploring the Natural History of its banks; the plan being to make for ourselves a collection of objects, dispose of the duplicates in London to pay expenses, and gather facts, as Mr. Wallace expressed it in one of his letters, "towards solving the problem of the origin of species," a subject on which we had conversed and corresponded much together. We met in London, early in the following year, to study South American animals and plants at the principal collections; and in the month of April, as related in the following narrative, commenced our journey.
My companion left the country at the end of four years; and, on arriving in England, published a narrative of his voyage, under the title of "Travels on the Amazons and Rio Negro." I remained seven years longer, returning home in July, 1859; and having taken,
