TUK MAMMALIA OF THE UINTA FORMATIOX. 529 



stage of reduction of the lateral metapodials. This is further evidence that some 

 species of the Lower Miocene genus will be found to approach Triplojjus much more 

 closely than // nebi-asceiicis does. The ujjper molai's of the known species of Trip- 

 loj)us entirely lack the rhinocerotic "anticrochet" seen in /////rrnyf/o//. and are also 

 devoid of the strong external cinguluin. 



Another feature- of Diplajyu'^ should, however, be mentioned, which may serve to 

 justify Prof. Cope's views of its separate systematic position, that is, the apparent ex- 

 pansion of the tympanic into a small auditoi-y bulla. The meatifs anihtarins exteiiivs 

 is completely enclosed bi'low, whereas both in llijrachyus and ILjracodim it is widely 

 open. 



We probably have in T'rrploims a highly specialized cursorial type in which there 

 is a slightly more marked tendency to monodactylism than in the predominant spe- 

 cies of cither llijrach ijm or ILjracodon. A recently completed restoration of II. ne- 

 brascmcis from materials in the Princeton and Harvard Museums shows that the 

 Miocene genus retained substantially the proportions of jryrachijus tximhis as seen in 

 the complete skeleton discovered by Cope. 



EPIIIIPPUS Martili. 



This genus is represented ijy the lower jaw and numerous portions of the skele- 

 ton of a single young individual (No. 10,405). The species cannot be determined. 

 The specimen is provisionally referred to E. uintensis Marsh. 



Generic characters. Dentition, i. ^, c. j, pra. |, m. j|. The third and I'ouith 

 upper premolars are like the molars, and the corresponding lower premolars have the 

 double antero-internal cusps (a a Riitimeyer). The ulna is complete and distinct 

 fiom the radius. The lunar rests equally upon the magnum and unciform. Digits 

 4-3. 



EiTiiiri'iis UINTENSIS Marsh. 



Plate XI, 



Dentitiou. The lower jaw is shallow, tapering to the narrow, slender symphysis. 

 The incisor fangs (Figs. 3, 3r0 are equidistant and subequal. The canine is conside- 

 rably larger. The first premolar has a simple pointed crown and single fang, 'i'he 

 premolars 2-4 are missing. The second molar has the characteristic reduplicatiun of 

 the antero-internal cusps. From the antero-external cusp ( protoconid ) a sharp 

 ridge extends downwards and inwards ; there is a well-defined external cinguluin. 

 The third molar shows the same characters with a strong posterior cingulum. The 

 superior teeth are not preserved. 



