LETTER TO THE SECRETARY. ix 



specimeDs. In general terms, it may be said, that, in llie determination of 

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

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

 is hoped, slious that tlic study of fossil plants gives no less reliable data than 

 those afforded by animal remains ia the investigation of land formations. 



During the whole course of his researches npon tlie Mesozoic and 

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

 with Ileer, Schimper, Saporta, and other eminent paIa3o-botauists of Europe, 

 who have commented npon the progress of his labors in the most flivorable 

 terms, and have unequivocably confirmed his conclusions. AVhatever 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 tlie learning and ability of its illustrious 

 author, and a monument to the science he has for years cultivated with the 

 most gratifying success. If he may not be said to have created palaeo-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 Slates Geologist. 



Hon. Gael Scuuez, 



Secretary of the Inlcrior, Wasliington, V. C. 



T F — H 



