C. Deperet — Oligocene of the Roanne Basin. 351 



Stampian (Upper Oligocene), being well characterized by the 

 above-named species of Aceratherium. The fourth member 

 of the series, or marly limestone of Digoin, carries the same 

 species of Anthracotherium as Division 3, and cannot be 

 younger than of Middle Stampian age. There are no strata, 

 therefore, in the Roanne basin that can be properly referred 

 to the Aquitanian (or Lower Miocene), as has formerly been 

 thought. 



Postscriptum added by the Translator. 



As a result of Professor Deperet's determination of the ver- 

 tical succession of Tertiary strata in the Roannais, Lyonnais, 

 and adjacent regions, it is now possible to synchronize more 

 precisely than was formerly the case the different mammifer- 

 ous horizons throughout various parts of France and elsewhere. 

 One may compare, for instance, the tabulation given above 

 with the following arrangement of mid-Tertiary beds in the 

 Paris Basin, which is adopted by Paul Lemoine in his recent 

 work, La Geologie du Bassin de Paris (191 1) : 



Miocene. 



Tortonian . . . . Faluns de l'Anjou. 



Faluns de Touraine. 



Helvetian ._ Sables de Sologne. 



Burdigalian Sables de POrleannais. 



Aquitanian Calcaires de POrleannais. 



Oligocene. 



Chattian Meulieres de Montmorency. 



Stampian Sables de Fontainebleau. 



Sannoisian Calcaire de Brie. 



The general correspondence of these time divisions and 

 depositions with Xorth American formations will appear from 

 the table appended below, which has been drawn up by Mr. O. 

 A. Peterson, of the Carnegie Museum, from the most recent 

 data available, including the results of his own Held studies 

 and those of the late Mr. Hatcher : 



In South Dakota, as is well known, the Oligocene is much 

 more extensively developed than in the Nebraska region, and 

 comprises three clearly marked faunal zones, which have been 

 named as follows : (1) Titanotherium beds (= Lower White 

 River or Chadron beds) ; (2) Oreodon and Metamynodon beds 

 (= Middle White River) ; and (3) Leptauchenia and Proto- 

 ceras beds (= Upper White River). The middle and upper 

 members of the White River are grouped together by some 

 geologists under the term of Brule formation, which attains a 

 maximum thickness of about 400 feet, or about double that of 

 the lower member (= Chadron or Titanotherium beds). In 



