United States Geological Survey, 



Division of Palaeontology, 



New Haven, Conn., Becemher 18, 1884. 



Sir : 



In compliance with yonr letter of instructions, dated October 5, 

 1882, I have the honor to transmit herewith a Monograph of the 

 Dinocerata, an extinct order of Mammals discovered in the Eocene 

 deposits of Wyoming Territory. 



Very respectfully, 



Your obedient servant, 



0. C. MARSH, 

 Pal(Bontologist-in- Charge. 

 Hon. J. W. Powell, 



Director of the U. S. Geological Survey, 

 Washington, B. C. 



