LOWER JAW IN THE OX. 89 



gland, or a little dried ptyalin, as well as saliva, rapidly trans- 

 forms starch into dextrine and grape-sugar (p. 22). 



Lips. The lips in the ox are composed, as in similar 

 animals, of muscular fibres, and areolar tissue, and glandular 

 bodies, covered in part by skin, and more largely by mucous 

 membrane. While the lips are not very prominent in the ox, 

 their distinct muscles are fewer than in the human body. The 

 lips in the ox are not of the same importance as prehensile 

 organs as in the horse. With the tongue the ox seizes the 

 grass, the incisors cut it with an upward motion, and then the 

 lips assist in conveying it to the mouth. The upper lip is short. 



Cheeks. The cheeks are composed of muscular fibres and 

 areolar tissue, enclosed between the internal mucous lining of 

 the mouth and the integuments of the face. The principal 

 muscle, as in other animals, is the alveolo-labialis or buc- 

 cinator, and this is large. The effect of the muscular con- 

 traction of the cheeks is powerfully to diminish the capacity 

 of the cavity of the mouth. 



Lower Jaw- A notice of the action of the lower jaw is re- 

 quired to complete the account of the parts concerned in the 

 changes of the aliment within the mouth. The lower jaw, as 

 compared to that in man, is longer in proportion to the size of 

 the skull, and is destitute of the chin or mental process. The 

 condyles are rounded to permit the free motions of the jaw in 

 the mastication of the food. The lower jaw is comparatively 

 smaller than in the horse. The inferior border is convex ; the 

 condyles are double-concave laterally, and convex from before 

 backwards ; and the coronoid process turned backwards and 

 outwards. The two lateral branches are never ossified to- 

 gether, even in old animals. The lateral motion of the jaw is 

 very conspicuous in the ox, and may be seen at times to be 

 kept up for long periods without interruption, the mouthful 

 being first masticated on one side and then on the other. 



