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LETTER OF TRANSMITTAL- \ 



Washington, January 1, 1883. 



Sir: I have the honor to transmit for 3-onr approval the third vohnne of 

 the series ot final reports of the United States Geological Survey of the. Ter- 

 ritories, which during its existence was nnder my charge. 



Tlie present volume, which has been prepared by the eminent paleon- 

 tologist. Prof K. D. Cope, of Philadelphia, represents the labor of several 

 years, both in the field and in the study, and may l)e regarded as one of the 

 most important contributions to the rich field of vertebrate paleontology of 

 the western Territories ever made in this country. 



It was the original purpose to include all the material in the author's 

 possession from the Cenozoic and Mesozoic formations in the third and 

 fourth volumes of the series, but they accumulated to such an extent that 

 it became necessary to limit them to the Cenozoic alone. Therefore, the 

 two volumes are essentially one in subject matter. 



This volume consists of 1002 pages of text, illustrated with more 

 than one hundred plates, and the fourth volume, which is to follow, may be 

 regarded as a continuation of the present one, both comprising the material 

 in the author's possession from the Cenozoic formations of the West. 



The two volumes are divided into four parts, viz: 



Part I, Puerco, Wasatch, and Bridger Faunse (Eocene); 



Part II, White River and John Day Faunse (Lower and Middle 

 Miocene) ; 



Part III, TicholejDtus and Loup Fork Faunse (Upper Miocene); and 



Part IV, Pliocene. 



