The Patoka Quadrangle, described in Folio No. 105 of the U. S. Geological Survey, published in 1904, covers nearly the whole of Gibson County. An examination of this folio shows how complicated are the later geological features of the region. It is fair to suppose that a well from 30 to 40 feet in depth was dug, especially at that time, in the higher parts of the county, where the elevation is somewhere near 500 feet above sea-level. Here such a well would probably go through the rather scattering Wisconsin deposits of various kinds or through the loess referred to the Iowan stage, reaching perhaps the Sangamon; or through later Illinoian or early Sangamon lake deposits and Illinoian glacial accumulations into pre-Illinoian deposits. The folio cited notes (p. 3) the presence of deposits supposed to belong to the beginning of the Illinoian stage. These contained zones of black muck and other organic materials; and in places were found logs and what were thought by the well-diggers to be “black-oak” leaves. All these might have been of Aftonian age; and in deposits of that time might have been found the jaw of _Mylohyus nasutus_. This species has been reported from a number of other localities; but the remains have been of so imperfect character that the identifications may have been erroneous. Professor Cope reported in 1869 (Proc. Amer. Philos. Soc., vol. XI, p. 176) that he had found several molars and canine teeth of this animal in cave breccia in Wythe County, Virginia. The breccia appeared to be very old, and in them were found a species of _Megalonyx_, _Equus complicatus?_, _Tapirus haysii_, _Ursus amplidens_, and many other extinct species. Cope in 1899 (Jour. Acad. Nat. Sci. Phila., vol. XI, p. 263) announced this species from the Port Kennedy cave in southeastern Pennsylvania. In this case there were found only a canine and 4 molars; hence not too much reliance must be placed on the identification. A large majority of the numerous species found in the Port Kennedy cave are extinct. Among these are species of _Megalonyx_, a mylodon, a bear, 2 species of saber-tooth tigers, a tapir, 1 or 2 species of horse, and 3 species of peccaries. One can hardly doubt that the animals belonged to the early part of the Pleistocene. The indications are that the known examples of _Mylohyus nasutus_ belonged to the first half of the Pleistocene; that is, to the Sangamon stage or to the Aftonian.