Say, Thomas (1787–1834), a United States naturalist. He wrote the first major American works on insects (American Entomology, 3 volumes, 1824–28) and shells (American Conchology, 2 volumes, 1830–34). Say was born in Philadelphia. He served as zoologist on the United States government expeditions, led by Stephen H. Long, to the Rocky Mountains (1819–20) and the source of the Minnesota River (1823). Say was curator of the American Philosophical Society, 1821–27, and professor of natural history at the University of Pennsylvania, 1822–28. He was a founding member of the Academy of Natural Sciences in Philadelphia.