Zoologist, born at Bonsyde, Linlithgow; educated at Merchiston Castle, Edinburgh, and at the university there; a lecturer on botany at Aberdeen (1850), professor of Natural History in Queen's College, Cork (1853), of Geology at Belfast (1854), and of Natural History in the University of Edinburgh (1870); accompanied the Challenger expedition (1872-1876) as head of the scientific department; knighted 1876; wrote "The Depths of the Sea" and "The Voyage of the Challenger" (1830-1882).