Two kinds of Baboon are included among the fossil mammals found in the middle Pleistocene deposits of Olduvai, Tanganyika Territory. One belongs to the extinct genus Simopithecus Andrews; it is closely related to the Gelada. The other was referred to Papio by Pohle, who did not give the author of the genus, but it may be assumed that he used the name as of Erxleben, 1777. This usage, now of long standing, was fixed by J. A. Allen (1925).