IIII-. IADI I IIUN o| Mil, llokx].., >H(i\VIN(, (,K.\I)I\1. INCKKASK IN SI/K 



(After Lull and Matthew.) 



I. Four-toed hone, Eobippu*. about one foot high. Lower Eocene, X. America. 



a. Another four-toed hone. Orohippus. a little over a foot high. Middle Eocene, X. America. 



j. Three-toed hone. Mesohippu*. about the size of a sheep. Middle Oligocene, X. America. 



4. Three-toed hone. Merychippus. Miocene, N. America. Only one toe reaches the ground on each foot, but 



the remain* of two othen are prominent. 



f. The ftnt one-toed hone, P'.iohippus, about forty inches high at the shoulder. Pliocene, X. America. 

 6. The modern bone, running on the third digit of each foot. 





