SOCIAL LIFE OF ANIMALS 



491 



extreme competition. In the " Struggle for Existence " they perish. 

 (6) Winds also prevent some dispersal of certain insects as in the 

 case of the heavy trade winds. (N. A. Cobb.) 



Domestication of Animals 



Cat. — The house cats are derived from a single wild species, the 

 dun wild cat, Felis ynaniculata of Northeast x^frica. There are now 

 about 30 races of domesticated cats, grouped into two main classes, 

 the long haired and the short haired. The Mexican hairless cat 

 and the tailless Manx cat are interesting mutations. (See p. 524.) 



Horse. — The horses of today have been traced to two wild 

 ancestors, Equus przewalski of Northern Asia, from which have been 

 derived the Oriental, the Arabian, the Mongolian, the North African 

 and the Eastern European races; the Equus caballus fossilis of 

 Europe, from which have sprung the German, Norman, English 

 and West European horses. In South America and in Europe, 

 the bones of human beings have been found with those of horses. 

 In Europe, prehistoric horses are associated with human relics of 

 the Bronze Age. The New World type, Eohippus, has been found 

 in the Wasatch Mts. of Western North America, in the Eocene 

 period. It was about the size of a fox with four toes and a fifth 

 digitary splint on each hind foot. In the middle Eocene, Orohippus 

 was about 14 inches high, with four toes on its front feet and 3 toes, 

 but no splints, on the hind feet. In the Oligocene period, Meso- 

 hippuSy about the size of a dog or coyote, had three toes on all its 

 feet. In the middle Miocene, Protohippus was the size of a Shetland 

 pony, with one long toe and two short ones on each foot. In the 

 Pleistocene, Equus appeared with only one developed toe and splints 

 of*the second and fourth on each foot. Remains of the Old World 

 type, Hyracotheriujn, have been found in the London clay and the 

 Eocene formations of Europe. 



Donkeys have been derived from two wild species, the Nubian 

 desert donkey, Equus taeniopus, and the onager, Equus onager, of 

 Eastern Asia. The Asiatic wild ass is exceptionally fleet. There 

 are today three varieties, the largest, called the kiang, found in 

 Thibet and up to the snow line. The second, the ghorkkar or onager, 

 found in the plains of Afghanistan, is smaller and silvery white. 

 The third variety, found in Persia and Syria, is the one described in the 

 Bible. The African ass is found throughout Northeastern Africa. 

 It ranges westward on the deserts and is exceedingly speedy. 



