EXTINCT ANIMALS 



interesting details in the history of the changes 

 of the teeth and toes of the ancestral series of 

 horses which it is not within my scope to 

 describe here, but they may be studied on speci- 



mtsostjtlt ptrail/lt 



Fig. 98. — Upper molar tooth of a recent horse. A, uncut and 

 unworn ; B, C, D, in successive stages of wear. 



mens of a variety of ancestral horses which have 

 been set out for the purpose in the Natural 

 History Museum. 



The rhinoceroses of to-day — the unicorn or 



142 



