CHAP. XVI 



Backboned Animals 



269 



folk " — seem to be allied. Both are often included in the great 

 order of hoofed animals or Ungulates, along with the odd-toed 



Fig. 58. — Phenacodus jirim&vus, a primitive extinct mammal from the lower 

 Eocene of N. America. The actual size of the slab of rock on which it rested 

 was 49 inches in length. (From Chambers's Encyclop. ; after Cope.) 



animals — horse, rhinoceros, and tapir, and a larger number of 

 even-toed forms, hog and hippopotamus, camel and dromedary, 



Fig. 59. — Head of gorilla. (From Du Chaillu.) 



and the true cud-chewers or ruminants such as sheep and cattle, 

 deer and antelopes. From the ancient predecessors of the modern 



