126 Life of Lower Lake Region. 



The enveloping sediment that has preserved 

 these bones in place for untold ages is now 

 changed to rock, showing the exact position 

 of the distal end of these rudimentary hoofs. 



The form of horse that most abounded 

 here in the early Miocene period was the An- 

 chitherium, a name Dr. Leidy found already 

 in use in Europe and so adopted for these 

 American fossils. It was a genus of three 

 or four species, varying in size from that of a 

 Newfoundland dog twenty-five to twenty- 

 seven inches in height, to that of a small 

 donkey. In spite of the many close resem- 

 blances between the skeleton of this Anchi- 

 therium and that of our living horse, there 

 were two features in which they differed 

 widely. In the molar teeth of the living horse 

 the divisions of the crown pass into prisms 

 nearly the whole length of the tooth, while the 

 corresponding molars of the Anchitherium 

 are planted in the jaw by fangs or roots. The 

 other feature in which they differ is in the 

 divisions of the foot. In Anchitherium there 

 were three continuous sets of bones in each 



