EVOLcriox or riii: iKmsE is \.\rria': 



29 



FiK 20. EVOLUTION OF THE TEETH. 

 LATER STAGES. Second r|)j)('r Molar 



(Head upj. (8) 

 M cr licit i j) jHi s, 

 Middle Mio- 

 cene; (<)) ////y- 

 jxirioii, rpper 

 Miocene; HO) 

 bUinuii .strnonis, 

 Pliocene; (11) 

 hjijiiii.^ compli- 

 adiis, Pleisto- 

 cene; (12) Equus 

 chhalluii, the 

 modern horse 



Fig. 19. EVOLU- 

 TION OF THE 

 TEETH. EARLIER 

 STAGES. Second 

 Upper Molar (Read 

 up). (1) Eohippus, 

 Lower Eocene; (2) 

 Orohippus, Middle 

 Eocene; (3) Epihip- 

 pus, Upper Eocene; 

 (4) Mesohippus 

 montanensis, Lower 

 Oligocene; ib) Meso- 

 hippus bairdi, Mid- 

 dle Oligocene; (6) 

 Miohippus, Upper Oligocene; (7) 

 Parahippus, Lower Miocene 



