HARTT, Charles Frederick, naturalist, born in Fredericton, N.B., 23 August, 1840; died in Rio de Janeiro, Brazil, 18 March, 1878. He was graduated at Acadia college, Wolfville, Nova Scotia, in 1860, but before completing his course had made extensive geological explorations in Nova Scotia. In 1860 he accompanied his father. Jarvis William Hartt, to St. John, N. B., where they established a college high school. He at once began to study the geology of New Brunswick, and devoted special attention to the Devonian shales, in which he discovered an abundance of land plants and insects. The latter still remain the oldest known to science. His work met the notice of Louis Agassiz, by whose invitation he entered the Museum of comparative anatomy in Cambridge as a student. He received an appointment on the geological survey of New Brunswick in 1864, and discovered the first proof of primordial strata in that province, he was one of the geologists of the Thayer expedition to Brazil in 1865, and since then has been the chief modern investigator of South American natural history. He explored the neighborhood of the coast from Rio Janeiro to Bahia while on this expedition, making large zoological collections, and with the material collected prepared his "Geology and Physical Geography of Brazil" (Boston, 1870). In 1868 he was elected professor of natural history in Vassar, but later in the same year he was called to the chair of geology and physical geography in Cornell. Two years afterward, and again in 1871. He made trips of exploration to the valley of the Amazon. At the request of the Brazilian minister of agriculture he visited Rio Janeiro in August, 1874, and submitted plans for the organization of a Brazilian geological commission. He was appointed in May, 1875, chief of the geological surveys of the empire, and continued in that office till his death. His collections are displayed in the National museum, of which in 1876 he was made director, and form the most complete repository of South American geology in the world. Professor Hartt was a member of various scientific societies, and in 1869 was elected general secretary of the American association for the advancement of science. He contributed occasional articles to scientific journals, and, besides the book mentioned above, published "Contributions to the Geology and Physical Geography of the Lower Amazons" (Buffalo, 1874).