Philadelphia, February 1, 1874. 

 SiE: Please find accompauying a catalogue of the species of verte. 

 hrata whose remains are known to occur in the various formations of 

 the cretaceous period west of the Mississippi Eiver. I preface itVith 

 a few notes on the stratigraphy of the upper beds, mostly taken while 

 attached to the United States Geological Survey during the summer of 

 1872. I desire to express my indebtedness for the loan of much valua- 

 ble material used in the present investigation to Professor B. F. Mudge, 

 of Manhattan, Kansas; also to Dr. John H. Jane way, post-surgeon at 

 Fort Hays ; to Professor Merrill, of Topeka, and to Messrs. Weltman 

 and Henry Swigart, of Bvanston, Wyoming. 



I am, with best wishes, 



EDWAED D. COPE, 



Paleontologist. 

 Dr. F. Y. Hayden, 

 Director of the United States Geological Survey of the Territories. 



