South; Dakota School of Mines 105 



the gums, grooves that con Id not have been caused by the at- 

 trition of the other teeth. The neck is short and massive and 

 well arranged for the attachment of strong muscles necessitated 

 by the great length and weight of the head. The limbs are long, 

 particularly the fore limb, and this in connection with the high 

 shoulder prominence, gives to the animal a peculiar stilted ap- 

 pearance. The foot, fore and hind, has two functional toes cor- 

 responding to the third and fourth of five toed animals. The 

 second and fifth are present, but only in rudimentary form. 



Much that has been said in regard to the structural features 

 of the Elotheres applies also in a general way to the Dicotylidae, 

 bat the latter represent a later development and tend more defi- 

 nitely toward the modern peccaries. 



The following list includes all of the species known from 

 the badland formations of the Black Hills region, both of the 

 Elotheridae and the Dicotylidae : 



Elotheridae ( Entelodontidae) . 

 Lower Oligocene. 



Elotherium (Entelodon) crassum Marsh. 

 Middle Oligocene. 



Elotherium (Entelodon) mortoni (Leidy). 

 Upper Oligocene. 



Elotherium (Entelodon) ingens Leidy. 



Elotherium (Entelodon) crassus Marsh. 



Elotherium (Entelodon )bathrodon Marsh. 

 Lower Miocene. 



Dinohyus hollandi Peterson. 

 Dicotylidae (Tagassuidae). 

 Middle Oligocene. 



Perchoerus probus Leidy. 



Perchoerus nanus (Marsh). 

 Upper Oligocene. 



Perchoerus robustus (Marsh). 



Perchoerus platyops (Cope). 

 Lower Miocene. 



Desmathyus siouxensis (Peterson). 



Desmathyus pinensis Matthew. 

 Upper Miocene. 



Prosthemnops crassigenis Gidley. 



