Joseph Leidy (lī´dē), 1823–91, American scientist, b. Philadelphia, grad. Univ. of Pennsylvania medical school. From 1853 he taught anatomy at his alma mater. He was also professor of natural history at Swarthmore College (1870–85) and served as chairman of the board of curators (1847–91) and president (1881–91) of the Academy of Natural Sciences of Philadelphia. He ranked among the foremost anatomists of the day, and his Elementary Treatise on Human Anatomy (1861) was long the best American textbook in the field. He studied the fossil beds in Nebraska and South Dakota and, later, in Wyoming and Oregon and classified the fossils collected by the F. V. Hayden survey. Three important monographs followed, Ancient Fauna of Nebraska (1853), Extinct Mammalian Fauna of Dakota and Nebraska (1869), and Contributions to the Extinct Vertebrate Fauna of the Western Territories (1873), all landmarks in American paleontology. He was the first to identify in the United States extinct species of the horse, camel, sloth, tiger, rhinoceros, and many other genera and species. His Flora and Fauna within Living Animals (1853) was epoch-making in the field of parasitology, and his Fresh Water Rhizopods of North America (1879), with his own notable drawings, is still one of the finest works in its field.
See biography by W. S. W. Rauschenberger (1892).