10 OSBORN. 



2. The Torrejon and Thanetien (Cernaysien) nearly Parallel 



The oldest fossil mammal beds of Europe are fhe fluvio-ma- 

 rine Glauconie dc la Fcrc (Aisne, 6 metres), containing Arcto- 

 cyon primcEvus, equivalent to the marine Sablcs-dc-BracJiciix, 

 also resting upon the Cretaceous which is immediately overlaid 

 by the lacustrine Calcaires ct sables dc Rilly (38 metres). These 

 together constitute the Thanetien (Lapparent, '85), with which 

 the purely fresh- water Cernaysien (Lemoine) beds in the vicinity 

 of Rheims are closely parallel. 



The Cernaysien has been almost universally paralleled with 

 the Pnerco, but many years ago, while studying the Cernaysien 

 fauna of Rheims, with the kind aid of the late Doctor Victor 

 Lemoine, I reached the conclusion that it was more recent than 

 Puerco (OsBORx, '90, pp. 51-62). This conclusion is now con- 

 firmed by the separation (Wortman and Matthew, '99, p. 28) 

 of the true Puerco fauna underlying the Torrejon fauna. The 

 Torrejon agrees closely with the Cernaysien, so far as we can 

 judge from evidence which awaits a more exact study of the 

 Cernaysien fauna than we have yet enjoyed. 



a. Multituberculates. It is especially interesting to com- 

 pare the number of grooves and tubercles upon the Xeo- 

 plagiaiilax (Cernaysien) and Ptilodus (Torrejon) fourth premolars 

 and first lower molars, as indicating a similar age. 



b. Among the Rodents or Primates (for the systematic 

 position of these animals is not definitely known, see Schlosser 

 and Matthew) compare Protoadapis (Cernaysien), dentition 

 2—1—3-3, and Plesiadapis with its reduced dentition, simple 

 molar type and enlarged incisors, with Indrodon (Torrejon) 



a I- 3- 3)- 



c. Creodonts. Of the Mesonyehidee, Hyeenodictis (Cernay- 

 sien) is a little more modern than Dissaciis (Torrejon) in its 

 lower molars. Of the Aretocyonidc^, Arctocyon gervaisii (Cer- 

 naysien) and Arctocyon (Claenodon) corrngatns (Torrejon) are to 

 be compared. 



d. Ungulates. As hypothetically ancestral to the Ancy- 

 lopoda, PlciiraspidotJierinni (Cernaysien) is in an earlier stage 



