LETTER TO THE SECRETARY. 



Office of the United States Geological and 



Geogkaphical Survey of the Territories, 



Washington, D. C, January 1, 1878. 



Sir: I have the honor to transmit herewith, for your approval and f(jr 

 publication, the Seventh Volume of the Final Eeports of the Survey under 

 my charge. 



The work consists of a Report on the Tertiary Flora of the West, by 

 Prof Leo Lesquereux, of Columbus, Ohio, being Part II of ''Contributions 

 to the Fossil Flora of the Western Territories"^Part I being "The Cre- 

 taceous Flora", by the same distinguished author, whose long-continued 

 studies in palseo-botany have placed the subject upon a firm and enduring 

 basis. Part I formed Vol. VI of this series of Final Reports, and the 

 present Part constitutes Vol. VII. 



The circumstances which led to the preparation of this work may be 

 briefly reviewed. 



When the geological investigation of the Lignitic formations of the 

 West had reached a certain point, the conclusions derived from such studies 

 were discussed by certain geologists who dissented from the views then 

 expressed respecting the age of these strata. It consequently became 

 desirable, in order to the solution of the questions involved, to elaborate 

 further, and witli the greatest care, all availal)le material bearing upon this 

 interesting problem. To this end, I desired Prof Joseph Leidy, Prof E. 

 D. Cope, Mr. F. B. Meek, and Prof Leo Lesquereux, to present in detail 

 all the evidence they could secure in their respective specialties of Extinct 

 Vertebrata, Extinct Invertebrata, and Fossil Flora, bearing on the disputed 

 age of these formations, to decide, if possible, whether the strata in question 

 are Cretaceous or Tertiary. The various reports which these gentlemen 

 have furnished testify with what zeal, ability, and success these instructions 

 have been carried out. 



