GILL, Theodore Nicholas, naturalist, born in New York City, 21 March, 1837. He was educated in his native City in private schools, and under special tutors, His attention was early turned to natural history, and for some time he was associated with J. Carson Brevoort in the arrangement of the latter's entomological and ichthyological collections. In 1863 he went to Washington and became an assistant in the Smithsonian institution. His work there consisted in the study and classification of the material that had been collected under the auspices of the institution, and his attention was first given to mammals, and later to fishes, in which departments he is recognized as one of the foremost authorities. More recently he has devoted considerable thought to mollusks. He also held the office of librarian in the Smithsonian, and for some years was senior assistant librarian of congress. From 1884 till 1887 he was professor of zoology in the Columbian University, Washington, D. C., from which institution he has received the honorary degrees of A. N., M. D., and Ph. D. Dr. Gill is a member of scientific societies, and in 1873 was elected to the National academy of sciences. His publications include, besides some 400 separate papers on scientific subjects contributed to the publications of various learned societies of which he is a member, "Arrangements of the Families of Mollusks" (Washington, 1871); "Arrangement of the Families of Mammals" (1872); "Arrangement of the Families of Fishes " (1872) ; "Catalogue of the Fishes of the East Coast of North America" (1875): '" Bibliography of the Fishes of the Pacific of the United States to the End of 1879" (1882); and since 1879 has prepared the "Reports on Zoology" for the annual volumes of the Smithsonian institution.