Pp. x, (1), 508, 11 black-and-white photo-plates, numerous text-figures and maps. Publisher's original green cloth, spine is lettered in gilt, pictorial two-color dust jacket, lg 8vo. From the jacket "The islands of the Sea of Cortéz (Gulf of California) off northwestern Mexico, scattered over nearly five hundred miles, provide what Darwin found in the a natural laboratory for evolutionary studies and ecological research on the colonization and extinction processes." The volume includes 12 chapters by noted authorities in all aspect of physical geology and biology. No ownership marks.