14 OSBORN. 



polophus)vivernna of the Wasatch, while Rutimever's supposed 

 StypolopJius does agree with the Siiiopa brcvicalcarata of the 

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

 phodon, Palceouictis 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 Liitc- 

 tien 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. moycn. ct infer ^ but become fresh- 

 water or flu\"iatile at the summit {Ca/c. gros. super.) where they 

 contain Lophiodon and many other ungulates. 



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

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

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

 Lemoine, of Bracklesliani (England). Certain types of Biichs- 

 tveiler, 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 // ody 

 corresponds ivitli a seetion of the npper J Find River or the Loiuer 

 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 Paheonictis gigaiitea. 



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

 dominant in number and variety. 



