OF WESTERN NORTH AMERICA. 



77 



Douglass (150 feet), Montana, (c) Mountain Region: 6, Mascall for- 

 mation, Oregon (lower part, 1,000 feet), capping the Columbia River 

 lava (1,000 feet), which in turn overlies the John Day formation. 

 The Colorado (Matthew") and Montana (Scott,'' Douglass^) faunae 

 are the best known and are closely equivalent in age. 



Europe. — Homotaxis with Europe is provisional, owing to: (1) Un- 

 certainty as to what we should regard as the base of the American 

 Miocene; (2) uncertainty as to the speed or rate of migration from 

 Europe. The new mammals of this stage (viz, Proboscidea, Teleo- 

 cerinae, and Pecora) are all from Europe, where they form the chief 

 characteristics of the lower Miocene ; but we may suppose that these 

 animals occupied a portion of the lower Miocene period in migrating 

 from western Europe to North America. 



FAUNA.^ 



1. Scott first (1893^) fully characterized the upper Deep River 

 fauna of Montana as prior to the so-called ''Loup Fork" of Colorado. 



2. Matthew^ first (1901) clearly distinguished the fauna of our 

 so-called middle Miocene (''Pawnee Creek") from that of the upper 

 Miocene or typical Niobrara River "Loup Fork" of Hayden, and the 

 above correlations are chiefly due to him. 



3. Its negative characters are: Nonoccurrence of Artiodactyla- 

 Elotheriidse and Hypertragulidse (which apparently became extinct 

 during the lower Rosebud); of Perissodactyla-Diceratheriinge (which 

 apparently became extinct during the upper Rosebud). 



4. Its positive or new characters are: (1) The first appearance of 

 Proboscidea by migration from Africa. (2) By migration from west- 

 ern Europe or Eurasia: Among Carnivora 2 new and distinctive 

 Eurasiatic subfamilies — (a) true Felidse-Felinse, Pseudselurus; (h) 

 Canidse-Amphicyoninse, Amphicyon. Among Perissodactyla-Rhi- 

 nocerotoidea, a member of the Teleocerinse closely similar to the 

 lower Miocene Teleoceras aurelianensis of France. Among Artiodac- 

 tyla-Cervidse, Palxomeryx; other peculiarly American modernized 

 ruminants, Merycodus (family Antilocapridse), date from this stage. 

 Among Rodentia the new family Mylagaulidse (also American) 

 appears. Thus in our so-called middle Miocene the peculiarly 

 American Hypertragulidge disappear; the European Cervidge and the 

 peculiarly American Merycodontinse take their places. 



a Matthew, W D., Fossil mammals of the Tertiary of northwestern Colorado: Mem. Am. Mus. Nat. 

 Hist., vol. 1, pt. 7, Nov., 1901, pp. 355-447. 



b Scott, W. B., The Mammalia of th3 Deep River beds: Trans. Am. Philos. Soc, n. s., vol. 18, 1895, 

 pp. 55-185. 



c Douglass, Earl, The Neocene lake beds of western Montana: Univ. Montana, doctorate thesis 

 June, 1899. New vertebrates from the Montana territory: Ann. Carnegie Mus., vol. 2, 1903. 

 d See Appendix, p. 91. 



e Scott, W. B. The mammals of the Deep Jliver beds: Am. Naturalist, vol. 27, 1893, pp. 659-662. The 

 Mammalia of the Deep River beds: Trans. Am. Philos. Soc, n. s., vol. 18, 1895, pp. 5.5-185. 

 /Matthew, W. D., op. cit., pp. 358-374. 



