THE FORERUNNERS OF THE HORSE 253 



depression in front of the eye-socket, but that of 

 Onohippidium has a long and deep oval pit in this 

 position divided into two distinct portions. Remains 

 of this group of extinct horses have been found in 

 the superficial deposits of the pampas of Argentina, 

 and also in caverns in Patagonia, Brazil, Bolivia, 

 Peru, and Ecuador. The Peruvian species was de- 

 scribed in 1908 by Mr. Nordenskiold ^ as Oiiokippi- 

 dium peruanuniy but in 19 10 was made the type of a 

 distinct genus, under the name of Hyperhippidium 

 peruanum} 



In all three genera the crowns of the cheek- 

 teeth are shorter than in Eqtitts ; and those of the 

 upper jaw are characterised by the equality in the 

 size of the grinding surfaces of the anterior and 

 posterior pillars on the inner side. 



Hoofs of Onohippidium have been found in a 

 remarkably fresh state of preservation in a cavern 

 at Ultima Esperanza (Last Hope) Inlet, Patagonia, 

 in association with the skin and hair and other 

 remains of an extinct giant ground-sloth {Grypo- 

 theritwz). Since it is practically certain that the 

 latter lived during the human period, it is most 

 likely that the same was the case with Onohippidium. 

 Now it has been suggested that certain wild horses 

 seen in Argentina by John Cabot in the year 1530 



^ Arkiv fiir Zoolo^^, Stockholm, vol. iv. No. 11, p. 17. 

 * I. S&ioQ,^'' Hyperhippidium, GixiG. neue Siidamerikanische Pferde- 

 gattung," Stockholm, Vet. Ak.-Handl. vol. xlvi. pt. 2, p. i. 



