LETTER TO THE SECRETARY. 



Office U. S. Geological Survey of the Territories, 



Washington, D. C, March 1, 1874. 



Sir : I have the honor to transmit for publication the very valuable 

 report of Prof. Leo Lesquereux on the Fossil Flora of the Cretaceous Dakota 

 Group. This division, lying at the base of the Cretaceous series, forms a 

 most important link in the physical history of the western portion of the 

 continent, containing as it does the first proofs of the introduction on the 

 earth of a vegetation allied to our fruit and forest trees. The formation also 

 has a vast geographical extension, being exposed along the flanks of the 

 various mountain-ranges, from a point far north of our northern boundary, 

 and extending far south to Mexico. Nearly all the fossil forms, however, 

 vegetable or animal, that it has yielded up to this time, have been found on 

 the jjlains in the eastern portions of Kansas and Nebraska. 



This elaborate memoir of Professor Lesquereux will be indispensable 

 to every student of the geology of the West, and will reflect great credit on 

 the survey at home and abroad, and its immediate publication is earnestly 

 requested. 



Very respectfully, your obedient servant, 



F. V. HAYDEN, 

 United States Geologist. 



Hon. C. Delano, 



Secretary of the Interior. 



