8o 



THE NEOG^IC REALM. 



[CHAP. 



genera are shown in the accompanying figures (13 and 14); the 

 letters indicating the corresponding elements in each. 



FlG. 13. GRINDING SURFACE OF RIGHT UPPER MOLAR OF Macrauchenia. 



FlG. 14. GRINDING SURFACE OF RIGHT UPPER MOLAR OF 



Oxyodontotherium . 



The second family, or Proterotheriidce, is confined to the Monte 

 Hermoso, Parana, and Santa Cruz beds of Patagonia, in the last 

 of which it is represented by the genera Proterotherium and Dia- 

 diaphorus. In these animals, none of which much exceeded a 

 sheep in size, the upper molar teeth are much more like those of 

 the European Palceotherium ; and, in place of forming a continuous 

 series, the teeth are interrupted; one pair, both in the upper and 

 lower jaw, being developed into tusks. In structure the feet pre- 

 sented a general resemblance to those of the extinct three-toed 

 horses (Hipparion) of the northern hemisphere, but in some in- 

 stances the toes were reduced to a single one, thus showing a 



