UNGULATA. 



427 



Fam. 3. Palaotheridce. This family includes certain ex- 

 tinct Ungulates from the Eocene and Miocene Tertiary. They 

 are characterised by the possession of three toes to all the feet, 

 by having canines, and by the fact that the lower molars have 

 a doubly crescentic form. The canines are longer than the 

 other teeth, and the dental formula is 



3 3 J I 4 4 3 3 



/ ; c- -; pm- r ; m- = 44. 



33 



44 33 



The chief, if not the only, genus in this family is Palceotherium 

 itself. Several species of this genus are known, varying in size 

 from a sheep up to a horse. From the size and form of the 

 nasal bones, it is deduced, with great probability, that the Palae- 

 othere possessed a short movable proboscis or trunk (fig. 352). 



Fig. 352. Outline of Palceo therium magnum, restored, after Cuvier. Upper Eocene. 



All the known species of Palceotherium are Eocene or Miocene, 

 and the genus attained its maximum in the former period. 



Fam. 4. Solidungula or Equidce. This family comprises the 

 Horses, Asses, and Zebras, characterised by the fact that the 

 feet have only a single perfect toe each, enclosed in a single 

 broad hoof. There is a discontinuous series of teeth in each 

 jaw ; and in the males, canines are present, but these are 

 wanting in the females. The dental formula is 



.33 



i i 



pm 



33 



m 





= 40. 



33 i i 33 33 



The skin is covered with hair, and the neck is furnished with 

 a mane. 



