Making due allowances for environment and the hazards attending preservation and collection, the Aftonian and Sheridan fauna is practically the same as that found at Fossil Lake, Oregon. Furthermore, it may be traced along the plains into Texas and to the shores of the Gulf. Here, at or near tide-level, or not far away, may be found horses, camels, elephants (_E. columbi_ and _E. imperator_), _Mammut americanum_, and mastodons with teeth presenting trefoils. In Texas, within a mile of the Louisiana line, _Elephas imperator_ has been collected. The fauna reappears on the west coast of Florida; also on Peace Creek; on the east coast at Vero; at Brunswick and Savannah, Georgia; along Ashley River, near Charleston; probably also on the banks of Neuse River, 16 miles below New Bern, North Carolina; and again probably at Long Branch, New Jersey, where _Megatherium_ has been found; and finally at Port Kennedy, on Schuylkill River, about 25 miles above Philadelphia. All along the coast, apparently from the Rio Grande to Long Branch, the localities which furnish Aftonian fossils are within a few feet of sea-level. XII. THE YARMOUTH INTERGLACIAL STAGE. Up to the present time the interglacial soils found in a few localities between the Kansan and the Illinoian drifts have furnished only scanty remains of vertebrate fossils—a rabbit and a skunk at the type locality in Iowa. Certainly, however, the same animals were living then that were found at later stages. XIII. THE ILLINOIAN GLACIAL STAGE. To the Illinoian glacial stage the writer refers the collection of fossil vertebrates which was described in 1908 by Barnum Brown (Mem. Amer. Mus. Nat. Hist., vol. IX, pp. 157–208) and which had been obtained in the Conard fissure near Willcockson, Newton County, Arkansas. It is placed here rather than in the Sangamon stage, because of the number of species present which suggest a rather cold climate. A list of these species will be found on pages 31–32 of volume XXIII, of the Iowa Geological Survey. XIV. THE SANGAMON INTERGLACIAL STAGE.