THE MAXILLARY BONES. 37 



sunk : the axis of the condyle is oblique, and rotary move- 

 ments are largely made use of in triturating food. 



In the Felidse, it is strictly transverse ; their teeth, 

 adapted for slicing but not grinding, would gain nothing 

 by lateral motion, which is rendered quite impossible by 

 the manner in which the long transverse condyles are 

 locked into the glenoid cavity by strong processes in front 

 and behind. Curiously enough the interarticular cartilage 

 is present, but as the condyle never moves forward, the 

 cartilage is not attached to the external pterygoid muscle. 



In Herbivora the condyle is roundish, the ascending ramus 

 long, the pterygoid muscles large, and the glenoid cavity 

 shallow ; in the whale, which of course does not masticate at 

 all, there is no interarticular cartilage, and no synovial mem- 

 brane; the articulation is reduced to a mere ligamentous 

 attachment. 



The harder a substance is, the farther back between the 

 molars it is placed ; and as the food escapes from between 

 the teeth it is constantly being replaced by the lips, cheeks, 

 and tongue, the buccinator muscle being largely concerned 

 in this work of preventing morsels of food from escaping 

 from the teeth during its mastication. 



Just as the muscles of mastication vary in their relative 

 development in accordance with the food to be dealt with, 

 so also do the salivary glands. 



As a rule herbivorous creatures have large parotid glands; 

 that is to say, those creatures which deal with the driest 

 food and masticate it the most have this gland largely 

 developed. For instance it is very large in Ruminants ; 

 in Herbivorous 'Marsupials it is larger, in the carnivorous 

 section smaller, than the submaxillaries. When an espe- 

 cially viscid fluid is required, as, for example, that which 

 lubricates the tongue of an ant-eater, this is furnished by 

 exceedingly large submaxillary glands. 



The nerves of the teeth are derived from branches of the 



