THE EVOLUTION OF THE TERTIARY MAM- 

 MALS, AND THE IMPORTANCE OF 

 THEIR MIGRATIONS 1 

 PROFESSOR CHARLES DEPERET 

 University of Lyons 



Note.— These very interesting and important papers 

 by Charles Deperet, Dean of the Faculty of Science, Uni- 

 versity of Lyons, France, have been especially revised by 

 the author (to date, November, 1907) before translation. 

 The translation is the work of Miss Johanna Kroeber, 

 graduate student of Columbia University. Dr. Charles 

 R. Eastman of Harvard University and Dr. AY. D. Mat- 

 thew of the American Museum have kindly revised the 

 translation. The correlation of the Tertiary of the Old 

 and New World is of such commanding interest to pale- 

 ontologists, zoologists and geologists, that this contribu- 

 tion from one of the foremost paleontologists of the con- 

 tinent is especially welcome. 



Henry Fairfield Osborn. 



March 3, 1908. 



First Paper. Eocene Epoch 

 In a preceding contribution (Comptes rendus, 5 juin, 

 1905) upon the principles of evolution of the Tertiary 

 mammals, I have enunciated the following general law: 

 that when we attempt to establish the sequence of the 

 forms which represent the evolution of a natural phylum 

 we find ourselves, after tracing them backward through 

 a geologic series of more or less length, almost always 

 arrested by an impassable hiatus; this apparent break 

 corresponds to the sudden appearance of the group under 



1 Extract from the Comptes rendus des seances de VAcademie des Sci- 

 ences, t. CXLI. p. 702. (Seance du 6 novembre, 1905.) Translated by 

 Johanna Kroeber. 



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