Gideon Algernon Mafttell, an English geologist, born in Lewes, Sussex, in 1790, died in London, Nov. 10, 1852. He was educated as a surgeon, and attained a lucrative practice in his native town. Inclination, however, led him to devote much time to geological researches, and in a few years his discoveries in the Wealden formation, the extraordinary fossiferous richness of which had been previously little known, gave him a high rank among living palaeontologists. To his labors science is indebted for the discovery of four out of five of the genera of extinct dinosaurian reptiles, viz.: the iguanodon, the hylaosavrus, the pelorosaurus, and the regnosaurus; and his valuable museum collected from the Wealden and chalk formations, and which waspurchi in 1839 for £5,000 by the trustees of the British museum, contains well preserved fossil- of these, and also of many extinct fishes, insects, and plants. Bis geological drawings were bequeathed to Yale college, from which institution he received the degree of LL. D. in 1844. In 1825 he was elected a member of the royal society; in 1835 he received the Wollaston medal of the geological society, and in 1849 the royal medal of the royal society.

In 1 he removed to London, where he continued his medical practice and geological researches, and was remarkably successful as a lecturer. His chief scientific work separately published is "Fossils of the South Downs, or Illustrations of the Geology of Sussex" (4to, London, 1822). He is also the author of two popular treatises of great merit, "The Wonders of Geology' (2 vols., London, 1838), and "The Medals of Creation, or First Lessons in Geology" (2 vols., 1844), both of which have been translated into German, and of a number of other works illustrating the geology of the British isles And his own discoveries, including a "Pictorial Atlas of Fossil Remains" (4to, 1850). In Agassiz and Strickland's Bihliographia Zoologia et Geologic, 67 works and memoirs by Dr. Mantell are cited, besides which he wrote several papers on antiquarian and professional snbjects.