The last captive birds were divided in three groups around the turn of the 20th century, some of which were photographed alive. Martha, thought to be the last passenger pigeon, died on September 1, 1914, at the Cincinnati Zoo. The eradication of this species is a notable example of anthropogenic extinction. Swedish naturalist Carl Linnaeus coined the binomial name "Columba macroura" for both the mourning dove and the passenger pigeon in the 1758 edition of his work "Systema Naturae" (the starting point of biological nomenclature), wherein he appears to have considered the two identical. This composite description cited accounts of these birds in two pre-Linnean books. One of these was Mark Catesby's description of the passenger pigeon, which was published in his 1731 to 1743 work "Natural History of Carolina, Florida and the Bahama Islands", which referred to this bird as "Palumbus migratorius", and was accompanied by the earliest published illustration of the species. Catesby's description was combined with the 1743 description of the mourning dove by George Edwards, who used the name "C. macroura" for that bird. There is nothing to suggest Linnaeus ever saw specimens of these birds himself, and his description is thought to be fully derivative of these earlier accounts and their illustrations. In his 1766 edition of "Systema Naturae", Linnaeus dropped the name "C. macroura", and instead used the name "C. migratoria" for the passenger pigeon, and "C. carolinensis" for the mourning dove. In the same edition, Linnaeus also named "C. canadensis", based on "Turtur canadensis", as used by Mathurin Jacques Brisson in 1760. Brisson's description was later shown to have been based on a female passenger pigeon. In 1827 William John Swainson moved the passenger pigeon from the genus "Columba" to the new monotypic genus "Ectopistes", due in part to the length of the wings and the wedge shape of the tail. In 1906 Outram Bangs suggested that because Linnaeus had wholly copied Catesby's text when coining "C. macroura", this name should apply to the passenger pigeon, as "E. macroura". In 1918 Harry C. Oberholser suggested that "C. canadensis" should take precedence over "C. migratoria" (as "E. canadensis"), as it appeared on an earlier page in Linnaeus' book.