PROGRESSIVE EXPANSION OF CRANIUM. 223 



propensity to slay and devour: it is the material symbol 

 of the lowest animal passion. 



In the bird (Fig. 48), the brain-case has expanded ver- 

 tically and laterally, but is confined to the back part of 

 the skull. In the small singing birds, with shorter beaks, 

 the proportion of the cranial cavity becomes much greater. 



Fig. 49. 



In the dog (Fig. 49), the brain-case, with more capacity, 

 begins to advance further forward. In the chimpanzee 



Fio;. 50. 



CHIMPANZEE. 



(Fig. 50), the capacities or area of the cranium and face 

 are about equal. In man, the cranial area vastly surpasses 

 that of the face. 



