1A 



DIAGRAM SHOWING SEVEN STAGES IN THE EVOLUTION OF THE FORE-LIMBS AND HIND-LIMBS 



OF THE ANCESTORS OF THE MODERN HORSE, BEGINNING WITH THE EARLIEST KNOWN 



PREDECESSORS OF THE HORSE AND CULMINATING WITH THE HORSE OF TO-DAY 



(After Marsh and Lull.) 



i and IA, fore-limb and hind-limb of Eohippus; 2 and 2A, Orohippus; 3 and 3A, Mesohippus; 4 and 4A 

 Hypohippus; 5 and SA, Merychippus; 6 and 6A, Hipparion; 7 and 7A, the modern horse. Note how the 

 toes shorten and disappear. 



