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UINTA SELENODONTS 



The species of Protoreodon are as follows : 



Protoreodon parvus S. and O. 

 Proc. Amer. Phil. Soc, 18S7, p. 257. 



Characterized by the presence of three upper incisors and by the small 

 development of the in'ner cusp on p^. Size moderate. Upper molars with 

 strongly concave outer crescents. 



Protoreodon pumilus Marsh. 

 Agriochwriis pumihts Marsh, Amer. Journ. Sci., 3d Ser., ix., p. 250. 

 Eome7yx pumilus Marsh, Ibid., xlviii., p. 266. 



Upper incisiors two ; p- like p-*- ; upper molars with less concave outer 

 crescents. 



Protoreodon paradoxicus Scott. 

 Agriotherinm paradoxicutn Scott, Proc. Amer. Phil. Soc, 1898, p. 79. 



Cranium very long, face short; upper incisors one, premaxillse not meet- 

 ing in the median line. Upper molars with very concave outer crescents ; p-^- 

 without inner cusp. 



Protoreodon minor sp. nov. 



Size smaller than preceding species ; p-*- with very small inner cusp. 



In addition to these a large species, almost rivalling Oreodon culbertsoni in 

 size, is indicated by limb and foot bones in the Princeton collection and in that 

 of the American Museum. (See Plate III., fig. 22.) 



The Taxonoviic Position of Protoreodon and the Relationships 

 of the Oreodontidce. 



There would appear to be two lines of development included within 

 the genus Protoreodon, one of which is characterized by the reduction of the 

 upper incisors, and which culminates in the genus Hyomeryx, which is without 

 upper incisors altogether. In the other line the incisors are retained. The 

 first series apparently died out at the end of the Uinta, leaving no successors 

 in the White River. The second series, represented especially by P. parv2is, 

 seems without doubt to be the direct forerunner of Oreodon and its successors. 

 The Uinta genus resembles the White River form in every part of the dentition, 

 skull, and skeleton, but is, of course, less modified and in every way what we 

 should expect the ancestral genus to be. Thus the incisors and canines have 



