328 



HISTORICAL PALAEONTOLOGY. 



Val d'Arno, near Florence. Like the preceding, it survived, 

 in diminished numbers, into the earlier portion of the Post- 

 Pliocene period. 



The Horses {EquidcB) are represented, both in Europe and 



Fig. 249.— A, Under surface of the skull of Rhinoceros Et-nescus, one-seventh of the 

 natural size— Pliocene, Italy ; B, Crowns of the three true molars of the upper jaw, left 

 side, of Rhinoceros juezarkinus (R. leptorhinus. Falconer), one-half of the natural size 

 — Pliocene, France. (After Falconer.) 



America, by the three-toed Hipparions, which survive from the 

 Miocene, but are now verging upon extinction. For the first 

 time, also, we meet with genuine Horses {Eqmis)^ in which 

 each foot is provided with a single complete toe only, encased 

 in a single broad hoof. One of the American species of this 

 period (the Equus excelsus) quite equalled the modem Horse 

 in stature ; and it is interesting to note the occurrence of indi- 

 genous horses in America at such a comparatively late geo- 

 logical epoch, seeing that this continent certainly possessed 

 none of these animals when first discovered by the Spaniards, 

 Amongst the Even-toed Ungulates, we may note the occur- 



