Troxell — Dicer atherium and the Dicer atheres. 19T 



Art. XV.^ — A Study of Diceratherium and the Dicera- 

 theres;^ by Edward L. Troxell. 



[Contributions from the Othniel Charles Marsh Publication Fund, Peabodj 

 Museum, Yale University, New Haven, Conn.] 



Table of Contents. 

 Introduction. 

 The true diceratheres. 



Diceratherium Marsh. 



Diceratherium lohatum, sp. nov. 



Diceratherium cuspidatum, sp. nov. 

 The diceratheres of the Great Plains. 



Menoceras cooTci (Peterson), gen. nov. 



MetaccFMopus egregius (Cook). 

 Summary. 



Introduction. 



At present there are but two species of Diceratherium, 

 D. armatum and D. annej^tens, which are accepted without 

 reservation by students of paleontology; yet species 

 from two continents have been referred to the genus, as 

 well as all specimens from the John Day region of 

 Oregon and those from the Lower Miocene of the Great 

 Plains. 



Our inability to classify harmoniously all the two- 

 horned rhinoceroses under this genus does not tend to 

 lessen its importance nor its distinction, and although 

 there is a wide variation in John Day rhinoceroses, it is 

 necessary to put them together into one group and at 

 the same time separate that group from all others. 

 Following is a list of the Oregon species of the true 

 Diceratherium : 



Diceratherium hesperium (Leidy) 1865. Inadequate. 



Figured heautotype. Cat. No. 10239, Y.P.M. 

 Diceratherium pacificum (Leidy) 1871. Inadequate. 



Figured heautotype. Cat. No. 10287, Y.P.M. 

 Diceratherium annectens (Marsh) 1873. Holotype, Cat. 



No. 10001, Y.P.M. 

 Diceratherium armatum (Marsh) 1875. Genoholotype. 



Holotype, Cat. No. 10003, Y.P.M. 



^ This is the last of the series of four papers on the American rhinoceroses. 

 Three other parts appeared in this Journal for July, 1921. It is a pleasure 

 to state that all of the drawings in these four papers were made by Eudolph 

 Weber, whose work is so well known to scientists everywhere. 



