THE LIGNITIC FORMATION AND ITS FOSSIL FLORA. 



BY LEO l^SQUEEEUX. 



COLTJMBUS, Ohio, July 14, 1874. 



Dear Sie : I send you herewith my report on the botanical paleon- 

 tology of the Tertiaiy formations of the Eocky Mountains. 



The results of the explorations of 1873 in regard to my special 

 researches are exposed in the description of the new species of fossil 

 plants, and in the discussion of the data famished by these plants on 

 the age of the Lignitic formations. 



As there has been of late some discussion on this last subject, and 

 as the opinions of the explorers do not yet agree, I have reviewed in the 

 first part of my report the facts and arguments bearing evidence on 

 the age of the Lignitic ; in the second part, I have marked, by tables, 

 &c., the distribution of the Tertiary flora in relation to the periods which 

 they seem to represent ; in the third part, the description of the new 

 species, or of those which were not yet known from American specimens, 

 is given ; and the fourth has a review on the climate during the North 

 American Tertiary epoch, as indicated by the character of the groups of 

 its fossil flora. 



Besides what is due to the co-operation of the members of your corps 



in the collection of specimens of fossil plants, the survey is greatly 



indebted to Captain Berthoud, and to Mr. A. Lakes, of Golden, for the 



discovery of new species and the communication of splendid specimens. 



Very respectfully, yours, 



L. LESQUEEEUX. 



Dr. E. V. Hatden, 



United States Geologist, Washington. 



