This collection includes correspondence on natural history and evolution, and especially on his collection and study of shells from Japan and the Pacific islands. Principal correspondents include Louis Agassiz, Charles Robert Darwin, Sir William Henry Flower, Alpheus Hyatt, George Newbold Lawrence, George J. Romanes, Alfred R. Wallace, and the Linnean Society of London.

One of the most important natural historians in nineteenth century Britain, Charles Darwin provided the first compelling mechanism to account for organismal evolutionary change. Although lacking a coherent model of heredity, Darwin's natural selection has exerted an enormous influence over the biological sciences and since the introduction of Mendelian genetics, had remained the key unifying principle in the discipline. The APS Darwin Papers are a large a valuable assemblage of Darwin's correspondence with scientific colleagues, including Charles Lyell and George J. Romanes. They are included in the print version of the Correspondence of Charles Darwin (Cambridge Univ. Press).