116 
The Evolution of the Horse. 
the first case, and Nos. I. and V. in the second ; whilst othe 1 !' 
changes had taken place in the skeleton and in the teeth that 
would require detailed description and illustrations in order to 
be intelligible. 
The animals formed upon this type, which are met with in 
a somewhat later geological epoch, present considerable diver- 
sity of characters, and we find them gradually breaking up in 
different groups, some of which, after undergoing a considerable 
degree of specialisation, became extinct without leaving suc- 
cessors. But three of these modified types, already distinct at 
the close of the Eocene period, have continued up to the present 
day, gradually, as time advanced, becoming more and more 
divergent from each other. These, as already mentioned, are 
now represented by the three families of the tapirs, the rhino- 
ceroses, and the horses. ' 
The tapirs have retained much more of the original character 
of the primitive Ungulates of the Eocene period than any of the 
others, and have, indeed, remained practically unchanged since 
the Miocene period ; while almost all other mammalian forms 
which existed then have either become extinct or undergone 
extensive modification. They appear now to be animals tending 
to extinction, for though formerly having had a wide range of 
distribution, through the continents of America, Europe, and 
Asia, they are now only found at two rather isolated parts of 
the world — i.e. South and Central America, and the Malay 
region — and they are by no means numerous either in species or 
individuals. They are shy, solitary, nocturnal, and inoffensive 
animals, chiefly frequenting the depths of shady forests and the 
neighbourhood of water, to which they frequently resort for the 
purpose of bathing, and in which they will take refuge when 
pursued. They feed chiefly on various vegetable substances, as 
shoots of trees and bushes, buds and leaves. Their nose is pro- 
longed into a sort of short, prehensile proboscis. In the structure 
of the feet they scai'cely differ from llyracotherium. They are, 
in fact, as mentioned before, good old conservatives, which have 
scarcel)* departed in any way from the manners, customs, or 
structure of their ancestors. 
The second branch of the family can be traced through 
gradual modifications to the modern rhinoceroses, which in many 
respects are more •specialised than the tapirs. They have but 
three toes upon each foot, and the teeth have been considerably 
changed, some species having lost all the incisors, or cutting 
teeth, of the front of the mouth. They have, moreover, acquired 
the peculiarity of wearing one or two large horns upon their 
noses, which the early species of the family did not possess. 
