112 FOSSIL HORSES. 



these reasons, probably, that their remains are almost 

 always more numerous than those of other orders of 

 mammalia. In America they are especially abundant. 

 " The true horses are represented in the Pliocene by 

 several ancestral forms. The most nearly allied to the 

 modern horse is Pliohippus, consisting of animals 

 about the size of an ass, with lateral toes not exter- 

 nally developed, but with some differences of dentition. 

 Next come Protohippus and Hipparion, in which the 

 lateral toes are developed, but are small and function- 

 less, Protohippus being only two feet and a half high. 

 Then we have the allied genera, Anchippus, Merychip- 

 pus, and Hyohippus, which were still smaller animals. 

 In the older deposits we come to a series of forms, still 

 unmistakably equine, but with three or more toes used 

 for locomotion, and with numerous differentiations in 

 form, proportions, and dentition. In the Miocene we 

 have the genera Anchitherium, Miohippus, and Meso- 

 hippus, with three toes on each foot, and about the 

 size of a sheep or large goat. In the Eocene of Utah 

 and Wyoming we get a step further back, several spe- 

 cies having been discovered about the size of a fox, 

 with four toes in front and three behind. These form 

 the genus Orohippus, and are the oldest ancestral 

 horse known." (For a later discovery, see page 260.) 



The following account of a horse's tooth that was 

 found while digging a well is from Tlie Popular Science 

 Review : 



" In a paper read before the St. Louis Academy of 

 Science, and reported in The American Naturalist for 

 March, 1871, Mr. G-. C. Broadhead records some in- 

 teresting facts about fossil horses. Alluding to the 

 fact that horse remains have been found in the altered 



