xviii DINOCEKATA. 



The same general plan will be followed in the third Monogi'aph, on 

 the Sauropoda, which conies next in the series, and is now approaching 

 completion. Ninety lithographic plates, and a large number of woodcuts, 

 will be used to illustrate it. The fourth volume, on the Stegosauria, which 

 follows, will likewise be very fully illustrated. A great portion of the 

 lithographic plates to accompany it are finished, and part of them are 

 already printed. Other monographs of the series, now in preparation, 

 will appear in due time. 



To General Sheridan and General Sherman of the United States 

 Army, the author's best thanks are due for ini})ortant assistance in his 

 Western explorations, during which the discoveries here recorded were 

 made. Other officers of the Army, who commanded his escort, and aided 

 him in many ways, also deserve grateful acknowledgments. 



For direct aid in collecting the specimens on which tlie present 

 volume is based, the author is indebted to the members of the Yale 

 College expeditions, which explored so successfully many portions of the 

 Western Territories. 



The thanks of the author are especially due to Mr. Oscar Harger, 

 assistant in the Yale Museum, for valuable aid in the field, and in the 

 |)reparation of the present memoir. Messrs. S. W. Williston, G. Baur, and 

 i\I. Schlosser, also his assistants, have likewise aided, especially while the 

 volume was passing through the press. 



Yai,e College, New Haven, Conn., December 15th, 1884. 



