There are two prominent Natural History collections in Special Collections: the rare books and archives formely housed in the Hancock Library of Biology and Natural History and a collection of books by and about Charles Darwin given to the USC Libraries in the 1970s by the Slatkin brothers. The Hancock Collections and Archives comprises approximately 78,000 volumes of books and periodicals published between 1525 and 1944. Most of the collection was acquired by Captain G. Allan Hancock with his purchase of the Boston Society of Natural History library in 1944. The Hancock Collection covers a broad spectrum of scientific research, including botany, geology, microscopy, evolution, voyages and explorations, zoology and bacteriology. Lavishly illustrated books, important scientific works and rare journals from past centuries abound, among them Audubon's The Birds of America double elephant folio published between 1827 and 1846. A Bibliography of the Hancock Natural History Collection has been compiled by the curator and is available on demand. In addition, access to this collection is provided through the USC Libraries' online catalog.