16 THE DISEASES AND DISORDERS OF THE OX. 



this point at first sight seems to aflford a very good basis of 

 classification, it does not on further inquiry turn out to be one of 

 thorough and entire reliability. The extinct animal called Acero- 

 therium, in other points approaching the Perissodactyles, was 

 nevertheless provided with four toes on its fore limbs, as indeed 

 the tapir of the present day is. Again, the Anoplotherium was 

 like an Artiodactyle Ungulate, but it had three toes only on its 

 fore legs, albeit that the hind limbs had only two toes each. 

 Hence, as regards merely the actual number of the toes, a 

 gradation can be traced betwixt the Artiodactyles on the one 

 hand, and the Perissodactyles on the other. However, if we 

 take as our basis of classification the number of toes on which 

 the animal stands, in other words the number of those which are 

 actually used in supporting the animal's weight, we have a far 

 more strictly correct standard of comparison. 



All the Ungulata walk and run. They do not climb, and they 

 possess no clavicle or collar-bone. They never have more than four 

 digits, and they walk on the ends of the digits. The metacarpal 

 and metatarsal bones tend to assume a vertical direction. These 

 animals are adapted for swift progression. 



Ruminants masticate their food a second time, and they are all 

 cloven-footed, i.e. they have two proper digits on each foot. 

 Very generally the skull of a ruminant is provided with two 

 horns, one on each side ; and the ox, sheep, goat, and antelope 

 are classed as Cavicornia, because their horns are hollow and 

 supported on bony cores. As a rule ruminants are not pro- 

 vided with front teeth in the upper jaw, and the stomach in these 

 animals is very large and complex. 



Now in the Cavicornia, or hollow-horned group, including the 

 sheep and goat (which are very similar to each other), also the 

 antelopes and the Bovidse, the skin covering the cores afterwards 

 becomes horn. The placentation is cotyledonous.* Horns are 

 generally present in the males. Camels, tragulidse, and moschidse 

 have no horns. There are two kinds of antelopes in America, 

 namely the prong-buck and the mountain-goat. The prong-buck 

 throws off its hollow horns like the Cervidaj do. The chamois is 

 an antelope met with in Europe, and there are also some in 

 North America. Antelopes are chiefly found in Africa. Neither 



* That is, the placenta consists of sepai-ate rounded masses called cotyledons. 



