yO SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 128 



toward the metaconule and a rounded lobe toward the cleft between 

 paracone and metacone. There is no indication of the latter character 

 in Marsh's illustration. 



The highly rugose or plicate character of the enamel in Oromeryx 

 is well shown in the median valleys, and somewhat better on the 

 lingual than on the labial surfaces. The crests, where unworn, are 

 serrate, and the portions of a lingual cingulum exhibited are highly 

 cuspate, particularly between the protocone and metaconule and as it 

 is carried part way around the metaconule. The plicate character of 

 the enamel is not peculiar to Oromeryx but is likewise highly devel- 

 oped on most Protylopus material of the Uinta B stage and on teeth 

 of the Badwater form, Malaquijerus. 



Perhaps the significant features of Oromeryx, if Protylopus is to 

 be regarded as distinct, lie in the relative elongation of the teeth, an- 

 teroposteriorly, along the outer surface and the distinctly narrower 

 posterior portion in comparison with the anterior width of the upper 

 molars. The latter character was noted by both Scott and Peterson, 

 but their comparisons were made with various leptomerycids. This 

 distinction is somewhat emphasized by the incompleteness of the teeth 

 in the Oromeryx pUcatus type and, moreover, is less noticeable when 

 viewed with materials of Protylopus petersoni. 



OROMERYX PLICATUS se Marsh, 1894 

 Plate IS, figures 1-2 



Type. — Right maxillary fragment with P* and the lingual portions 

 of M^-M^ ; left maxillary fragment with M^ and the labial portion of 

 M2, Y.P.M. No. 14571. 



Horizon and locality. — Uinta B, mouth of White River (determined 

 from Marsh's notes pertaining to collection No. 1057), Uinta Basin, 

 Utah. 



MEASUREMENTS IN MILLIMETERS OF DENTITION IN SPECIMENS OF 



Oromeryx plicatus 



Y.P.M. 



No. 



I4S7I 



Type 



Length of upper cheek tooth series, anterior margin of alveolus for P' 



to posterior n>argin of M' 34.8 



Upper molar series, M*-M', inclusive 23.5 



P*, anteroposterior diameter : transverse diameter* : 5.7 



M\ anteroposterior diameter : transverse diameter* 7.4a : . . . 



M^ anteroposterior diameter : transverse diameter 8.3 : . . . 



M', anteroposterior diameter : transverse diameter 8.8 : 9.3 



38 Also illustrated in Marsh, 1894, fig. 23. 



