IN THE LOWER ANIMALS, ETC. 339 



types, witli the exception of the premolars, which, 

 as in the lower section, are still three in number. 



But we must dwell more particularly on the 

 third or highest section, comprehending, with 

 other genera, the mandrils and baboons, the orangs, 

 the chimpanzee, and the great gorilla. In all the 

 genera of this great division, the tail-less apes, the 

 teeth exactly correspond in number with those 

 of man. 



If we compare the skulls of the higher Quad- 

 rumana wdth those of animals lower in the scale 

 of intelligence, we shall observe, many remarkable 

 distinctive characters. The bones of the face 

 are shorter, and constitute a smaller portion of 

 the entire skull, while the cranium is proportion- 

 ally larger. 



The frontal bone becomes expanded, and the 

 orbits, surrounded by a bony ring, are no longer 

 directed towards the sides of the head, but are 

 much more approximate, and are directed for- 

 wards. The temporal fossa is smaller, and the 

 zygoma shorter and almost straight. The inter- 

 maxillary bones, which in most animals remain 

 distinct through life, are united to the maxillae in 

 a larger proportion and at an earlier period as we 

 approach the highest forms. The jaws become 

 shorter, the vertical ramus of the lower maxilla 

 is more developed, and the coronoid process is 

 smaller than in the Carnivora ; the condyle being 

 nearly flat, admitting of free lateral motion. 



z 2 



