THE FORERUNNERS OF THE HORSE 259 



whereas " in Me7'ychippus msignis the protocone, 

 while attached [by a neck of enamel to the adjacent 

 crescent], tends to become free, yet in Neohipparion 

 isonesum the reverse is true in that the protocone, 

 although free, shows a strong reluctance to leave 

 its old association with the anterior crest [crescent]. 

 In other species of Neohipparion this is not apparent, 

 the protocone being oval in section, and entirely 

 free in all stages of wear." 



In appearance the American hipparions were 

 deer-like, and therefore probably adapted to a high 

 rate of speed. They stood about 10 hands at the 

 shoulder, and were therefore smaller than their 

 relatives of the Old World. 



The skull of an hipparion from the Upper 

 Tertiary strata of Samos has been described by 

 Dr. H. Studer^ as a distinct species, under the 

 name of H. proboscideus ; the conformation of the 

 extremity of the upper jawbone leading him to 

 conclude that it was provided with a short proboscis 

 in life. As stated in the first chapter, he also 

 believes that in this and other cases where it occurs 

 the preorbital pit is for the attachment of muscles 

 required for the support and working of the pro- 

 boscis. From the fact that a preorbital pit occurs 

 in Merychippus, as well as in Onohippidmni and 

 other genera. Dr. Studer is inclined to think that a 



* Zeits. Deutsch. Zool. Ges., 1910-11, p. 11. 



