MEMOIES 



OS THE 



CAENEGIE MUSEUM. 



Vol. VII. No. 6. 



THE AMERICAN DICERATHERES. 



By 0. A. Peterson. 



(Plates LVII-LXVI.) 



Introductory. 



At the outset the writer wishes to acknowledge his indebtedness to Dr. W. J. 

 Holland for much valuable assistance and advice in the preparation of the following 

 paper, and for permission freely to use the material in the Carnegie Museum. 

 To the authorities of the Peabody Museum of Natural History at Yale University 

 thanks are due for their courtesy in allowing me to study and illustrate the types 

 of Professor 0. C. Marsh. I wish to express my gratitude to Professor F. B. 

 Loomis, of Amherst, for granting me free access to his collection of types and 

 drawings. I wish to gratefully acknowledge the kindness of the authorities of 

 the American Museum of Natural History for granting me the privilege of exam- 

 ining the material from the John Day beds forming a part of the collection of the 

 late Professor Cope, and allowing me to describe a new species of the genus Dicera- 

 therium. Thanks are also due to the Librarian of Congress for literature for- 

 warded for consultation to the Carnegie Museum, to Mr. James W. Gidley, of 

 the U. S. National Museum, and to Mr. Harold J. Cook for information. Mr. 

 Syndey Prentice has carefully executed the drawings here reproduced. 



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