14 OSBORN. 



polopJius) viverrbia of the Wasatch, while Rutimeyer's supposed 

 StypolopJuis does agree with the Sinopa brcvicalcarata of the 

 Bridger. Notwithstanding these facts, in the absence of Cory- 

 phodon, Palceonictis and other typical Wasatch and Suessonien 

 forms, the greatest age which can be positively assigned to the 

 beginning of these fissure formations is the lower portion of the 

 Middle Eocene. 



6. Middle Eocene, Lutetien, apparently parallel with the 



Wind River Fauna 



Constituting the base of the greater Parisicn stage, the L2itc- 

 ticii substage, first, marks the advance of the sea beyond its 

 Suessonien limits southward around Paris, and to the west and 

 north into Belgium ; second, it marks the appearance of fossil 

 mammal deposits in the south of France, in Switzerland (Hel- 

 vetien Canal), and in Alsace. 



The Calcairc grossicr beds (45 metres) are entirely marine in 

 their lower strata {Calc. gros. inoyen. ct infer}) but become fresh- 

 water or fluviatile at the summit {Caic. gros. snpcr.) where they 

 contain Lophiodon and many other ungulates. 



Parallel with these beds are those of the Grcs d' Isscl (Aude, 

 24 metres) fully studied by Filhol ('88) ; of Argenton (Indre) ; 

 of the Argilcs a lignites, or Agein (Rheims) explored by Dr. 

 Lemoine, of BracklesJiani (England). Certain types of BncJis- 

 weiler, Alsace, seem to be somewhat more recent. Finally our 

 knowledge of the mammals of this stage is greatly enriched by 

 the older portions of the fissure deposits of Egerkingen (Vaud) 

 and of Lissieu, near Lyons. 



This fauna has been hitherto paralleled with that of our great 

 Middle Eocene deposits of the Bridger ; we shall see that it only 

 corresponds with a section of the upper Wind River or the Lozuer 

 Bridger Lake deposits of the Rocky Mountains. 



Characteristics : Filhol ('88, p. i, 75), in his conclusion upon 

 the Issel fauna, speaks doubtfully of the presence of a large 

 Creodont, as Pahi^onictis gigantea. 



This is the continuation of the reign of Lophiodon, a type pre- 

 dominant in number and variety. 



