1316 



CLASS MAMMALIA. 



fectly known ; but Professor Cope, who makes it the type of a dis- 

 tinct family, states that it has tritubercular upper molars, and four 

 digits in the pes, and looks upon it as the ancestral type of the 

 Camels. Dr Schlosser is, however, not satisfied that the teeth are 



Fig. 1187.— Left aspect of the Hippopotamus (H. amphibius). Much reduced. (After Giebel.) 



really tritubercular, and suggests that it may indicate a transitional 

 type between the Artiodactyla and the Condylarthra. 



Family Hippopotamid^e. — This family contains the single Old 

 World genus Hippopotamus, now represented by two species of 



Fig. 1 1 88. — Left manus of Hippopotamus 

 amphibius. Reduced. (After Cuvier.) 



Fig. 1 189. — Left upper true 

 molar of Hippopotamus amphi- 

 bius. Two-thirds natural size. 



bulky animals, which spend a large proportion of their time in the 

 waters of lakes and rivers. In the skull (fig. 1187) the angle of the 

 mandible has a descending flange ; the facial portion is much elon- 



