LETTER TO THE GEOLOGISTIN-CHARGE. 



Columbus, Ohio, June 18, 1877. 



Dear Sir : I send you herewith my report on the Tertiary Flora of the 

 Territories. 



The work has three essential divisions. 



In the first, the general outlines of the geology of the countries where- 

 froni the specimens of plants have been obtained are briefly exposed. This 

 part is rather yours than my own. It could not be omitted, however, in this 

 volume; for it is advisable, for tiie understanding of the characters of the 

 floras, to have for reference an expose of the geographical and strafigraphical 

 distribution of the groups from which the specimens are derived. The quota- 

 tions on the subject are carefully credited to the original authors. 



The second part is the description of the species of fossil plants. 



The third reviews the evidence afforded by tlie fossil flora to the age and 

 the relation of the different groups of the Lignitic formations. The conclu- 

 sions derived from this review may not be generally admitted; they are, 

 however, confirmed by the careful comparison of the characters of the 

 vegetable remains. This part is prefaced by a few remarks upon the progress 

 of the work from the beginning of my connection with your Survey. I have 

 there mentioned the names of all those who have contributed to the Flora by 

 researches and communications of specimens. This mention is rightly due 

 to all, but especially to some friends who have worked hard and given much 

 time, without any remuneration, to procuring materials often of great value 

 to American paleontology. You will certainly find that they are all entitled 

 to a copy of the Flora, as they are also here to the expression of my most 

 sincere thanks. 



This Flora of the North American Lignitic is like a supplement to that 

 of the Cretaceous Dakota Group. Both together constitute a historical 

 record not less interesting to Botany than to Geology ; foi', beside the cvi- 

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