SUBORDER C 



PERISSODACTYLA 



137 



premolars molariform. 

 Nebraska and Colorado. 



Manus tridactyl. Oligocene ; White Eiver beds, 

 //. nebrascensis Leidy, H. major Osborn. 



Subfamily 2. Amynodontinae 

 Scott and Osborn. 



Skull deeply excavated in front of 

 the orbits, anterior border of the snout 

 broad, postglenoid process well de- 

 veloped. Nasal bones very short, 

 without horns. Superior and inferior 

 canines peccary-like tusks much more 

 robust than the incisors. Molars 

 like those of Rhinoceros, yet the trans- 

 verse crests of the superior molars 

 may be either without or with a very 

 weak crochet. Superior premolars 

 less complex or smaller than molars. 



Fig. 175. 



Hyracodon nebrascensis Leidy. Oligocene (White River 

 beds), Nebraska. Skull. Ve- (After W. B. Scott.) 



Manus tetradactyl, pes tridactyl. 



Fig. 176. 



The skeleton of one genus (Metamynodon) of these heavy aquatic quadrupeds 

 is well known. The skull, however, more nearly resembles that of the bear 



than of a perissodactyl. For 

 the most part, these compara- 

 tively rare remains come from 

 the Upper Eocene and Oligocene 

 of North America and from 

 the Oligocene of Europe. 



Amynodon Marsh (Ortho- 

 cynodon Scott and Osborn). 



Dental formula: ^fjll' - 

 2-1.1.4.3. 



Upper Eocene ; Wyoming. 



Metamynodon Scott and 

 Osborn (Fig. 176). Dental 



Metamynodon planifrons Osborn. Oligocene (White River 9 1 S S 



beds), Dakota. Skull, i/io- (After Osborn.) formula: "' i^'!^' " Cheekteeth 



laterally compressed. Crowns of the teeth very high. Oligocene ; White 



River beds, Dakota. According to Pilgrim, also in Burma. 



2. 1.3. .3. 

 Cadurcotherium Gervais. ','''' • Premolars and molars strongly com- 



1.1.2.3. ^ -^ 



pressed laterally. Oligocene ; Phosphorites, Quercy, Gypsum of Isle-sur- 



Sorgues. 



Subfamily 3. Rhinocerinae. 



Skull elongated, elevated posteriorly, without sagittal crest ; occiput surmounted 

 by a sharp occipital crest ; periotic not appearing on the outer surface of the skull ; 

 nasal hones long, projecting, of diverse strength, with or without horn-pad. Denti- 

 tion never quite complete. Dental formida : ' ' • Superior canines nearly 



always absent ; incisors frequently so. 



3-0. 0. 4-3.3. 



Superior first incisor and lower second incisor 



