LETTER TO THE SECllETAEY. IX 



specimens. In general terms, it may be said, that, in the determination of 

 marine formations, the remains of fossil plants have little value in comparison 

 with those afforded by fossil animals. But the conclusion of this volume, it 

 is hoped, shows that the study of fossil plants gives no less reliable data than 

 those aiforded by animal remains in the investigation of land formations. 



During the whole course of his researches upon the Mesozoic and 

 Cenozoic Floras of the West, the author has been in constant communication 

 with Heer, Schimper, Saporta, and other eminent palseo-botanists of Europe, 

 who have commented upon the progress of his labors in the most favorable 

 terms, and have unequivocably confirmed his conclusions. Whatever differ- 

 ence of opinion may continue respecting the age of the formation from which 

 the plants treated in this volume have been derived, the memoir will ever 

 remain an eloquent witness to the learning and ability of its illustrious 

 author, and a monument to the science he has for years cultiv^ited with the 

 most gratifying success. If he may not be said to have created palseo-botany 

 in America, he has been foremost in fostering it, and has brought it to the 

 point of advancement that is matched only by the standard of excellence 

 that the most eminent of his European compeers have attained. 



F. V. HAYDEN, 



United States Geologist. 



Hon. Carl Scuurz, 



Secretary of the Interior, Washington, D. C. 



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