684 MAMMALIA [CH. 



feet are purely adapted for running, the toes being encased in hard 

 blunt nails which are called hoofs. At the present time the 

 Ungulata include a number of very diverse forms. But it must 

 be remembered that a large proportion of the group is extinct, 

 and that to some extent the fossil forms serve to connect the very 

 heterogeneous members of the group that still exist. 



Sub-order 1. Sub-ungulata. 



In former times there existed a great assemblage of big and 

 often clumsy animals belonging to the Ungulata in which the toes 

 were all nearly equal in length and the bones of the wrist arranged 

 in parallel longitudinal series. The Sub-ungulata at one time 

 spread over the earth and in South America, which became isolated 

 in early times, they gave rise to a great variety of forms. Some of 

 these mimicked the members of the other sub-order of the Ungulata, 

 and formed one of the most striking examples of parallel evolution. 

 Only two families of the SUB-UNGULATA, as these animals are 

 called, survive at the present day. These are the family of the 

 Hyrax, HYRACIDAE, and the Elephant family, PROBOSCIDEAE. 



HYRACIDAE. 



The Hyrax (Procavia) is the Coney mentioned in the Bible. 

 The Hyracidae are small, not unlike rabbits in ap- 

 pearance, but their hind-feet closely resemble those 

 of the Rhinoceros. Their front teeth are, it is true, 

 somewhat chisel-shaped, as in the Rodentia, but there are four of 

 these below and two above, which is quite unlike the arrangement 

 in the rabbit. It is possible however that the two teeth reckoned 

 as lower posterior incisors may really be canines, since they do not, 

 like the other incisors and like those of the Rabbits, grow throughout 

 life (Fig. 342). These animals are found throughout Africa except 

 in the north and also in Arabia and Syria. Only one genus is now 

 recognised, Hyrax (Procavia), with several species. Most of these 

 live amongst rocks, in mountains and in stony places, but some 

 frequent the trunks and large branches of trees and sleep in holes. 



PROBOSCIDEAE. 



The Elephant is too well Ijnown to need much description, but it 

 may be pointed out that its trunk is really a long fiex- 

 ikle snout > an excessive exaggeration of what is found 

 in Insectivores, and that its tusks are front teeth, only 



