MAMMALIA. 

 FAMILY OREONTID^. 



21 



No. 3G. [57] Oreodon Culbertsonii, Leidy. 



Skull and Loweh Jaw (cast). 

 This remarkable ruminant un- 

 gulate constitutes one of the links 

 necessary to fill up the wide gap 

 between existing Ruminants and 

 the extinct Anoplotheria. The 

 form of the cranium proper ap- 

 proaches that of the Camel ; but 

 generally the skull bears most re- 

 semblance to the Anoplotherium. 

 It differs strikingly from the lat- 

 ter in the existence of post-orbital arches, in the greater size of the orbits, and 

 in the presence of deep lachrymal depressions. The sagittal crest is prominent, 

 and the forehead is convex. Tliej^ had four well-developed toes on each foot, 

 and fortj'-four teeth. The molars have a ruminant character. Canines and 

 incisors exist in both jaws and form with the molars almost unbroken rows, 

 the dentition appearing to characterize a ruminating Hog. This genus repre- 

 sents a family whicli is the earliest of the Selenodont Artiodactyla, and occurs 

 in prodigious numbers from the Middle Miocene to close of Pliocene in 

 America. This specimen was found in the Mauvaises Terres (Middle Miocene) 

 of Nebraska, and is in the possession of Dr. Leidy. Size, 8x5. 



FAMILY ANOPLOTHERID^. 



No. 37. [59] Anoplotherium. commune, Cuvier. 



Head on Slab (cast). This two-toed Ruminant was about the size of a 

 Fallow Deer. It had a long and strong tail, and was probablj^ of aquatic 

 habits. It was hornless, and had separate metatursal bones. But it is chiefly 

 remarkable for the completeness and regularity of its teeth. It has the typical 



