The Thousand Creek fauna (Merriam, Bull. Dept. Geol. Univ. Calif., vol. X, p. 429), which to the present writer appears of about the same age as the Blanco, contains a species of _Teleoceras_. The genera _Protohippus_ and _Procamelus_ might be supposed to have continued their existence and evolution until interrupted by an age of ice and by competitors from Asia.
In 1917 (Bull. cit., vol. X, pp. 255–266) Merriam and Buwalda published a short list of fossils which they had collected along the Columbia River in Washington State. A horse was found which was referred to _Equus_ or _Pliohippus_; also two camelids, one of which was thought to be near _Pliauchenia_. Merriam concluded that the evidence on the whole favored the Pleistocene. The list will fit into the Nebraskan without difficulty.
In 1889 (Amer. Naturalist, vol. XXIII, p. 253), Professor E. D. Cope published a list of fossil mammals collected in the “Oregon desert,” apparently somewhere in the region of Silver Lake or Summer Lake. The list is as follows:
Canis sp. indet. Elephas or Mastodon. Holomeniscus or Auchenia. Aphelops sp. indet. Hippotherium relictum. Equus sp. indet.
Cope looked upon this collection as remarkable in that it showed the presence of true horses and camels associated with a rhinoceros. He concluded that the fossils belonged to his Idaho formation. Dr. W. D. Matthew thought that the collection was a mixture of fossils from two formations (Bull. Amer. Mus. Nat. Hist., vol. XVI, p. 321). It may, however, have been made in Nebraskan deposits.
In 1921 (Proc. U. S. Nat. Mus., vol. LIX, pp. 617–638), the writer described a collection of vertebrate remains from Anita, Coconino County, Arizona. These remains were found in a cave in making explorations for copper ore. The list follows:
Equus occidentalis. E. giganteus? Mylohyus? sp. indet. Procamelus coconinensis. P. longurio. Antilocapra americana? Marmota arizonæ. Citellus tuitus. Neotoma cinerea. Lepus benjamini. Brachylagus browni. Taxidea robusta. Canis nubilus? C. latrans? Chasmaporthetes ossifragus.
The writer believes that this assemblage of mammals must be referred to the Pleistocene. It will be noted, however, that there are two species of the genus _Procamelus_. These resemble so much two species, _P. major_ and _P. minimus_, described by Leidy and Lucas (Trans. Wagner Free Inst., vol. IV, pp. I-XIV, 15–61) from the Alachua clays of Florida, that it seemed at first necessary to identify them as such. The genus _Procamelus_ seems, therefore, to be brought definitely into the early Pleistocene, probably the Nebraskan.