SUBORDER D 



ARTIODACTYLA 



185 



Frotoreodon Scott and Osborn (Eomeryx, Hijomeryx Marsli). Dental series 

 continuous. Superior molars very short crowned with three crescents in the 

 anterior and two in the posterior half of the tooth. All premolars mono- 

 cuspid or bicuspid. Orbits open posteriorly. Upper Eocene (Uinta beds) ; 

 Wyoming. P. parvus Scott. 



Limnenetes and Bathygenys Douglass. Similar to Oreodon, but with orbits 

 open behind. Lowermost White Eiver beds. 



Oreodon Leidy (Figs. 253, 254). Dental series continuous. Orbits closed 

 posteriorly. Lachrymal fossae large. Manus with fifth metacarpal, the pollex 

 very short, vestigial. Second and fifth metacarpals shorter than the two 

 median metacarpals. Pes tetradactyl. Exceedingly abundant in the White 

 River Oligocene ; North America. 0. culbertsoni, major, gracilis Leidy. 



Eporeodon Marsh (Eucrotaphus Leidy). 

 Skull elongated. Manus without pollex. ^ ^ 



Lower Miocene (John Day beds) ; Oregon 

 and Colorado. 



Mesoreodon Scott. Crowns of teeth rather 

 high. Allied to Eporeodon. Lower Miocene ; 

 Deep River beds. 



Oreodon culbertsoni'^ Leidy. Oligocene (Wliite River beds), 

 Nebraska. Skull and lower jaw. ^/g. (After Gaudry.) 



! Fig. 254. 



Oreodon culbertsoni Leidy. Oligocene 

 (White River beds), Nebraska. A, Fore 

 foot. B, Hind foot, i/s- (After W. B. 

 Scott.) 



Merycochoerus Leidy. Oreodont-like, but with shorter skull. Zygomatic 

 arch stronger and projecting further. Muzzle broad ; nasals shortened. 

 Premolar series short. Skeleton more robust and massive. Upper Miocene 

 (Loup Fork beds) ; North America. M. proprius Leidy. 



Pr ornery cochoerus Douglass (Figs. 255, 256, 257). Skull and premolar 

 series long ; nasals unreduced. Zygomatic arch thickened posteriorly. Lower 

 Miocene (John Day beds); Oregon. P. superbus Leidy (Fig. 255, B). Miocene; 

 Nebraska. P. carrikeri Peterson. 



Pronomotherium Douglass (Fig. 258). Skull extremely short. Premaxil- 

 laries united, with spout-shaped depression. Nasals short. Mandible heavy 

 and extremely large and deep. Incisors small. P. laticeps Douglass. Upper 

 Miocene; Montana. 



Phenacocoelus Peterson. Two elongated and narrow foramina at anterior 

 portion of frontals ; cranium long ; face short, large tympanic bulla. Leptau- 



