DOMESTICATED ANIMALS 327 



are abundant among the drawings made by late Glacial man on 

 cave walls in Spain and France. 



About a dozen living natural species and sub-species of the 

 genus Equus are known, including horses, asses, zebras, and the 

 now nearly if not quite extinct quagga. Of domesticated 

 races of horses and asses the number must run to more than a 

 score of well-marked distinct breeds, varying in size from the 



FIG. 140. Arion, a record-holding American trotting horse. (After 



Plumb.) 



minute ponies of the north British islands to the great Clydes- 

 dale and Percheron draught animals. 



Donkeys have been derived from two wild species, the Nu- 

 bian Desert donkey, Equus taniopus, and the onager, Equus 

 onager, of eastern Asia. Tame donkeys are figured in the 

 earliest of Egyptian and Assyrian drawings and carvings. 



The races of domesticated hogs are also descended from two 

 wild races, the European wild boar, Sus scrofa, and another 



