EQUID^. 465 



the Ehone and in Alsace. The two great races of horses are 

 the Oriental and the Occidental. In the Oriental or Arabian 

 we get the skull covering the brain strongly developed, and the 

 facial part smaller ; the enamel of the molars of the upper jaws 

 have few folds, and the limbs are fine. The Occidental Horse 

 has a much larger development of the facial part of the skull ; 

 the skull is long and narrow, the rims of the eye-cavities stand 

 somewhat forward, and the enamel folds of the crescents of the 

 upper molars are complicated. The bones are also thicker and 

 more massive, but less hard, than the Oriental. These two 

 main races of Equus cdballus, the Arab and the cart-horse, 

 have undoubtedly descended from a common stock, yet now 

 represent two quite distinct races. Wild horses were once 

 abundant in Europe and Asia, as their remains in the Diluvium 

 testify, and from these our Equus cahallus has descended. In 

 America, although we have plenty of equine remains, the genus 

 Equus never advanced in a wild state so near our present horse 

 as did the diluvial horses of Europe and Asia. 



The Ass {E. asinus) was domesticated before the horse. 

 Unlike the horse, there are no warts or chestnuts on the hind- 

 legs, and there is always a conspicuous line along the back, 

 whilst the tail is long, with a tuft of long hair at the extremity. 

 The ass is a native of North Africa, and probably descended 

 from either the Onager (E. onager) or Kiang {E. hemionus). It is 

 also said by some to be descended from E. tcenwpus of S.-E. Asia. 



Fossil horses exist in the Eocene rocks of America, known 

 as Eohippos, in which the fore-feet have four toes and the 

 remnant of a fifth, and the hind-feet three. The Eohippos was 

 about the size of a dog. A division higher in the Eocene, 

 another genus, Orohi]ipios, makes its appearance. In the Miocene 

 rocks we get another form, the Miohippos, which has three toes 

 on each foot, all touching the ground. In the Pliocene of 

 Europe we find a fossil horse called Hipparion in which three 

 toes exist on each foot, but the middle one alone touches the 

 ground. Towards the end of the Pliocene period we get the 



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