APPENDIX. 



RECENT DISCOVERIES OF FOSSIL HORSES. 



BY J. L. WORTMAN. 



THE contributions to the knowledge of the extinct Perisso- 

 dactyla,* made during the last two or three years in this 

 country, are of an important character, since they demonstrate 

 the actual existence of types heretofore hypothetically assumed. 

 The living representatives, the horse, tapir, and rhinoceros, 

 constitute but a small fraction of this large order when com- 

 pared with the fossil forms already known. One of these, 

 however, the horse, displays the most specialized structure to 

 be found within the liinits of the order. 



Many years have elapsed since the first discovery in the 

 Tertiary rocks of Europe of horse-like remains, which are 

 regarded by paleontologists in the light of direct ancestry of 

 existing equines. Since then the discovery of the remains of 

 these animals in the same geological horizons in this country, 

 by Drs. Hayden and Leidy, has strengthened the belief in the 

 descent of the horse from very different ancestral types. Entire 

 skeletons, obtained from the " bone beds " of the West, display 



* Odd-toed. The Perissodactyla may be defined as mammals having 

 both pair of limbs fully developed and adapted for walking or running, 

 the toes having terminal phalanges, incased in strong corneous sheaths, 

 developed as hoofs. These characters, however, apply to two other orders 

 also, the Artiodactyla (cloven-hoofed or even toed), and the Amblypoda 

 (short-footed), both of which, however, possess many anatomical differ- 

 ences from the Perissodactyla, particularly in the structure of their hind 

 limbs. 



