LETTER TO THE SECRETARY. 



Office of the United States 

 Geological Survey of the Territories, 



Washington, D. C, October 5, 1875. 



Sir: The very vnliiablc niemuir, l)y Prol". K. D. Cope, on the " Verte- 

 Iirala of the Cretaceous Formations of the West," is respectfully submitted for 

 your approval and for publication. The great interest which has been excited 

 among the peojjle, as well as among scientific men, l)y the discoveries of the 

 remarkable extinct vertebrate remains, within a few years past, in the num- 

 erous ancient lake-basins of the West, will render the publication very 

 opportune at this time, and one of great value to the intelligent world. As a 

 contribution of materials toward the solution of the numerous problems 

 involved in the geological structure of our great West, as well as the unfold- 

 ing of its ancient life, it must take the highest rank. 



In a certain sense. Paleontology, or the history of ancient organic remains, 

 lies at the very foundation of geological science. It oftentimes stands as the 

 arbiter on doubtful questions, and is a very important aid to the stratigrapher 

 in unfolding the age of strata, and in fixing the great timc-bnnndaries o( 

 groups, as well as divisions or sul»divisioiis. Xo geological survey can be 

 considered complete without its cooperation. It has l)ecn with this idea 

 that so much of the strength of the survey has been given to this department. 



So far as the opinions expres-sed by the author in regard to the age of 

 the Lignitic group are concerned, he aloni' is responsible to the scientific 

 world. In all the publications of the survey under my charge, prepared by 

 collaborators of established reputation, I have thought it best to permit the 

 broadest latitude in the expression of dpininns, w hetlier they liarnionize with 

 my own conclusions or not. While Professor ( 'oiie reads, in the teachin"-s ot 

 the extinct vertcbra'.e fauna of tlie Lignili>' irroiip, its Cretaceous age, Pro- 



