LETTER TO THE GEOLOG1ST-1N-CHARGE. 



Smithsonian Institution, 



Washington City, D. C. 



Sir: The following is my final report on the Cretaceous and Tertiary 

 fossils of the Upper Missouri country. It has been entirely rewritten since 

 the original publication of the brief preliminary descriptions of the species 

 in the Proceedings of the Academy of Natural Sciences at Philadelphia; and 

 full description of the genera and subgenera, with their synonymy and 

 references, and remarks on their geological and geographical ranges, have 

 been added. 



In this place, I desire to acknowledge my renewed obligations to Pro- 

 fessor Henry for many favors and facilities at the Smithsonian Institution 

 during the preparation of this report. For the use of rare and important 

 works, not accessible at Washington, I am indebted to the kindness of Prof. 

 James D. Dana and Prof. 0. C. Marsh, of New Haven; also to the lamented 

 Prof. Louis Agassiz, and, since his death, to his son, Prof. Alexander Agassiz, 

 of Cambridge, for similar favors. 



Without thereby intending to make any of the following gentlemen 

 responsible for conclusions finally adopted, I wish to express my thanks to 

 such naturalists and palaeontologists as have from time to time given sug- 

 gestions in regard to some doubtful points respecting the affinities of some of 

 the fossils here described. In this connection should be mentioned the names 

 of the late Dr. William Stimpson, Prof. Theo. Gill, and Wm. H. Dall, of Wash- 

 ington ; Messrs. George W". Tryon, T. A. Conrad, and Wm. M. Gabb, of 

 Philadelphia ; Mr. W. G. Binney, of Burlington ; Prof. Alpheus Hyatt, of Bos- 

 ton ; and Mr. Thomas Bland, of New York. 



I am likewise under especial obligations to Dr. A. C. Peale, of your 

 survey, for preparing a full index, table of contents, list of illustrations, etc., 

 for this report. 



F. B. MEEK, . 



Paleontologist. 



Dr. F. V. Hayoen, 



'£>' 



U. S. Geologist. 



H —III 



