THE RABBIT 295 



The Mouth and Pharynx; the Salivary Glands. Skin the head 

 and neck. Four pairs of salivary glands are present, all of which 

 open into the mouth. The parotid glands, the largest, are diffuse 

 white or light-brownish masses situated each just beneath the skin 

 and immediately below and behind the external ear; the duct 

 passes through to the inner surface of the cheek opposite the 

 second upper premolar tooth, where it opens into the mouth. The 

 submaxillary glands are more compact and are situated medial to 

 the hinder angle of the jaw ; the duct runs forward and opens in 

 the floor of the mouth. The sublingual glands are situated in 

 front of the submaxillaries and in contact with them; several 

 short ducts open into the mouth. The infra-orbital glands lie each 

 against the ventral wall of the orbit, and will be seen when the 

 orbit is dissected. 



Exercise 20. Draw an outline of the head and show the position of 

 the salivary glands, so far as observed. 



Cut away the lips and the muscles of the face and expose the 

 teeth. The dental formula of the rabbit is the following: in- 

 cisors 2/1, canines 0/0, premolars 3/2, molars 3/3, making eight 

 teeth in the upper jaw on each side and six in the lower jaw, or 

 fourteen on each side of the mouth and twenty-eight teeth al- 

 together. The rabbits and hares differ from all other rodents in 

 having four incisors in the upper jaw instead of two (as in the 

 case of guinea pigs and rats). The premolars and molars of rab- 

 bits are called the grinders and differ very little from one another 

 in form or appearance. 



Exercise 21. Draw a front and also a side view of the closed mouth, 

 with outlines of the teeth. 



Disarticulate the lower jaw, first cutting it with bone forceps, if 

 necessary, and turn it down, exposing the cavity of the mouth and 

 pharynx. The mouth is much the larger of these two regions, and 

 extends from the lips to the free edge of the soft palate ; the phar- 

 ynx lies between this point and the oesophagus and is the space 

 in which the path of the respiratory air from the nostrils to the 

 lungs crosses that of the food from the mouth to the stomach. 



