KEY TO PLATES. 



The teeth in all the Plates are drawn natural size. 



The skulls are drawn one-half natural size. 



The limbs and feet are drawn one-half natural size. 



PLATE 1 SKULLS: MESOHIPPUS, MI OH IP PUS PLATE 27 



2 UPPER TEETH: MESOHIPPUS " 28 



3 UPPER TEETH: MIOHIPPUS " 29 



4 UPPER AND LOWER TEETH: MIOHIPPUS " 30 



5 TEETH, FEET: MIOHIPPUS, HYPOHIPPUS " 31 



6 FACE: MIOHIPPUS, ARCILEOHIPPUS, ETC. " 32 



7 SKULL: PARAHIPPUS " 33 



8 UPPER AND LOWER TEETH: PARAHIPPUS " 34 



9 " " " " * 



10 FACE: MERYCHIPPUS " 35 



11 " " , OF PROGRESSIVE " 36 



TYPE " 37 



12 SKULL: MERYCHIPPUS SPHENODUS " 38 



13 UPPER TEETH: MERYCHIPPUS " 39 



14 UPPER AND LOWER TEETH: MERYCHIP- « 40 



PUS " 41 



15 UPPER TEETH: MERYCHIPPUS " 42 



16 " " " " 43 



17 " " " " 44 



18 SUPERIOR-INFERIOR MOLAR TOOTH " 45 



TYPE: MERYCHIPPUS " 46 



19 LOWER TEETH: MERYCHIPPUS " 47 



20 SKULL AND LOWER TEETH: MERYCHIP- " 48 



PUS " 49 



21 FACE: PROTOHIPPUS " 50 



22 TYPE TEETH: PROTOHIPPUS " 51 



23 FACE: PROTOHIPPUS, PLIOHIPPUS " 52 



24 TEETH: PROTOHIPPUS, PLIOHIPPUS " 53 



25 MILK TEETH: PARAHIPPUS-HIPPARION " 54 



26 FACE: MERYCHIPPUS, PLIOHIPPUS 



TYPE, PLIOHIPPUS LULLIANUS 

 UPPER TEETH: PLIOHIPPUS 

 TYPE, PLIOHIPPUS LEIDYANUS 



a a u 



TEETH: PLIOHIPPUS, HIPPARION 

 FACE: HIPPARION 

 TEETH: PLIOHIPPUS, HIPPARION 

 MILK TEETH: MERYCHIPPUS, PROTOHIP- 

 PUS, HIPPARION 

 SKULL AND TEETH: HYPOHIPPUS 

 HIND FEET: PARAHIPPUS 

 FEET: PARAHIPPUS 

 SKELETON: PARAHIPPUS 

 CARPUS: MIOCENE HORSES 

 SKELETON: KALOBATIPPUS 

 FORE FEET: MERYCHIPPUS 

 FEET: 



FORE FEET: 



U a a 



HUMERUS AND TIBIA: MERYCHIPPUS 



ULNA AND RADIUS: 



HUMERUS: 



ULNA AND RADIUS: 



a a u U 



FEMUR AND TIBIA: 



TARSUS: ANCHITHERIIN.E, HYPOHIPPUS 

 HIND FEET: MERYCHIPPUS 



221 



