U NITED STATES ENGINEER OFFICE, 

 EXPLORATIONS AND SURVEYS WEST OF THE IOOTH MERIDIAN, 



Washington, D. (7., October 3, 1874. 



The proofs of these reports, while passing through the press during 

 the absence of the authors in the field, were corrected by Mr. Kobert 

 Eidgway, of the Smithsonian Institution, to whom thanks are due for 

 his kindness in this regard, and who revised the nomenclature to corre- 

 spond with the latest information upon the subject. 



H. 0. Y. 



