50 



CENOZOIC MAMMAL HORIZONS 



It is clear that these beds must be referred to the Bridger, not to 

 the Wind Kiver. The Paramys compares most nearly with lower 

 Bridger species, but is too incomplete to settle its position without 

 very careful comparisons. There does not appear to be anything 

 else to indicate whether these beds are equivalent to lower or to 

 upper Bridger. The Patriofelis is a very much smaller species than 

 P. ulta of the lower Bridger or P. ferox of the upper Bridger. The 

 Tilloiherium is a characteristic Bridger animal. 



MIDDLE EOCENE EUROPE, ETAGES LUTETIEN SUPERIEUR, 



BARTONIEN). 



5. BRIDGER FORMATION; OROHIPPUS AND UINTATHERIUM ZONES. 



(Figs. 1, 2, 6, PL I.) 

 HOMOTAXIS. 



North America. — 1, Bridger formation of western Wyoming 

 (1,850 feet), including levels A, B, C, D, E. 2, Upper part of Huer- 

 fano formation of Colorado, 3, Lower beds, or Uintatherium zone, 

 in Uinta and Washakie basins of northern Utah (800 feet) in part. 

 4, Clarno formation of Oregon, Merriam; homotaxis provisional. 



Europe, provisional homotaxis. — Lower part of the Bridger approx- 

 imately equivalent to Lutetien superieur, represented by the Cal- 

 caire grossier (Paris basin), Issel, Buchsweiler, and later fissure 

 deposits of Lissieu and Egerkingen. Upper part of the Bridger 

 approximately equivalent to Bartonien (Calcaire de Saint Ouen, 

 Gres de Cesser as) in part. 



The whole vertebrate fauna, reptilian and mammalian, of this 

 period is better known than that of any of the other Eocene phases. 

 The mammalian summary is as follows: 



A marked numerical predominance, in the ratio of 4 to 3, of the 

 modern over the archaic genera of mammals. A single South 

 American mammal appears, the primitive armadillo Metacheiromys, 

 related to the Dasypoda. Affinities with western Europe are very 



CHIEF CHARACTERS OF THE FAUNA." 



Summary of genera. 



Archaic Cretaceous mammals . . 

 Modernized Tertiary mammals 



32 

 45 



77 



a See Appendix, p. 91. 



