18 GUIDE TO THE FOSSIL MAMMALS AND BIEDS. 



Table-case Jaws and limb-bones of the desman {Myogale moschata), an 

 2a - animal now confined to south-east Eussia, are shown from 

 the Norfolk Forest Bed. 



Oedee IV.— CHIROPTERA. 



Table-ease Fossil skeletons discovered in France prove that the bats 

 2a - were as completely formed in the Upper Eocene as they are 

 at the present day ; but there are only imperfect skulls and 

 jaws in the collection of the Museum (Table-case 2a). 



Oedee V.— UNGULATA. 



As the hoofed animals are traced backwards through 

 geological time, the fossils gradually lead to small marsh- 

 dwelling or forest-dwelling predecessors, which were adapted 

 to live on succulent vegetation. The existing tapirs, pigs, 

 peccaries, hippopotamus, and chevrotairis, are the least 

 altered survivors of this ancestry; while the rhinoceroses, 

 horses, cattle, giraffes, deer, and elephants, with effective 

 grinding teeth, are the highest and newest members of the 

 Order. 



Sub-oedee 1. — Perissodactyla. 



Pier-eases It seems probable that at the dawn of the Eocene period 



Table-cases a ^ ^he noo f e d animals were five-toed ; but most of them soon 



4, 5. began to exhibit a tendency towards the reduction of the 



spreading foot. In one group comprising the existing tapirs, 



rhinoceroses, and horses, the whole weight of the body 



gradually became concentrated on the middle toe, so that 



this grew stout at the expense of the other toes. Thus arose 



the uneven-toed hoofed animals or Perissodactyla. The 



tapirs retain four toes on the fore foot, three on the hind 



foot ; the rhinoceroses, three toes on each foot ; and the true 



horses, only one toe on each foot (see Fig. 9). 



Pier-cases The rhinoceroses, which are restricted to Africa and 



®~ 8 - the Indian region at the present day, wandered far from 



4~ tropical climes during the Pleistocene period and ranged 



over nearly the whole of Europe and Asia, being common 



even within the Arctic Circle. The northern species 



(Rhinoceros antiquitatis or B. tichorhinus) seems to have 



been most closely related to the nearly extinct square-nosed 



rhinoceros (It. simus) of Africa. It is commonly known as 



