MAMMALIA, 



5" 



e skeleton. Let us first glance at the skulls of the two 

 pes. Notice in both the large development of the facial 

 ^ion in comparison with the cranial. This is due not 

 ly to the large maxilla, but also to the part taken by the 

 yal and the lacrymal in the formation of this region. 



Fig. 351.— Ventral View of Skull of Horse 

 {Eqims Caballusy.\). {Ad 7iaf.) 



Hard Palate ■ — 



Internal Nares. 

 Pterygoid.. 



Tympanic '^i 



Occipital Condyle. 



Molars (three 

 Premolars in 

 front of them). 



'Glenoid Cavity. 



Foramen Magnum. 



ence the small size of the orbit, which is also completely 

 lunded by bone,* a postorbital process of the frontal 

 scending to meet the zygomatic arch below, 

 In both types the mandibles are large and heavy, ex- 

 nded behind into broad strong plates, evidently built 



* This complete closure of the orbit is not effected in the lower Perissodactyla 

 ,, Rhinoceros and Tapir), nor in the more primitive Artiodactyla {e.^., Pig). 



