38 bulletin united states geological sukvey. [yoly. 



Sables de Bbacheux and Con- Laeamie. 



GLOMERATE DE CeRNY. 



y. Cretaceous. 



Palceoscincus. 



Dysganus. 



Monoclonius. 



Diclonius. 



Cionodon. 



Lwlaps. 



Auhlysodon. 



If the Conglomerate of Cemy is the same horizon as the Conglomerate 

 of Meudon, we must add Goryphodon to the upper left-hand column, and 

 probably Gastornis also. The result is clear that the French and Ameri- 

 can formations together bridge most comi)letely the interval between the 

 Cretaceous and Tertiary series, as has been anticipated by Hayden, in 

 America, on geological grounds. It is also evident that another forma- 

 tion must be added to the series already recognized in France, viz, the 

 Laramie or Post-Cretaceous. This will be defined as the beds of the 

 genera GJiampsosaurus and Myledaplms. In France, the presence of mam- 

 malia will characterize the formation as a subdivision, for which it is 

 probable that the name Thanetian must be retained ; while to the Ameri- 

 can division, which is characterized by the presence of Dinosauria, the 

 name of Laramie beds has been given. 



The Eocene fauna is so varied, especially in Europe, that it is neces- 

 sary to compare the divisions separately, as in the case of the Cretaceous. 

 Thus, the fauna of the Suessonian is quite as distinct from that of the 

 Calcaire G-rossier and Gypse (Parisian and Tongrian) in France as are 

 those of the Wasatch and Bridger epochs in North America. 



I have already identified the Wasatch with the Suessonian or Orth- 

 rocene, on account of the community of the following genera in the 

 two continents: Goryphodon, Syracotheriuin, Aonhlyctonus, Glastes, and 

 a form of birds close to Gastornis. I can now add Fhenacodus, Grotlie- 

 rium (Cope), and very probably Hyopsodus, Adapts, Opistliotomus, and 

 Prototomus. But, as above mentioned, in the lower beds of the Sues- 

 sonian in France occur genera which are, so far as yet known, wanting 

 in the Wasatch of America, but present in the beds of the Laramie. 

 Such are two genera in the Conglomerate of Cerny, and four genera in 

 the lower Sables de Bracheux. In the former bed, they are associated 

 with the mammalian genera LopMochcerus, Flesiodapis, Pleuraspidotlie- 

 rkim, and Arctocyon; and in the lowest, with a form referred with doubt 

 to Syracotlierium. Thus the generalization may be made that the char- 

 acteristic genera of reptiles and fishes of the Laramie of ISTorth America 

 are in America associated with Cretaceous Pinosauria, and not with Mam- 

 malia; while in Europe they are associated with Mammalia, and not mth 

 Pinosauria. In arranging the Laramie Group, its necessary position is 



