KUMLNANTIA DIGESTIVE SYSTEM. 365 



free end of the teat. The teat is covered with skin, devoid of 

 hair ; and at its base is encircled by certain glands, secreting a 

 sebaceous lubricating matter which protects the teat during the 

 suckling of the young, and prevents plugging of the orifices by 

 coagulation of the milk. The mammoe are supplied with blood 

 by the mammary arteries, vessels corresponding to the external 

 pudics of the male. 



COMPARATIVE SPLAXCHXOLOGY. 



ALTHOUGH the viscera of the domestic animals are constructed on the same 

 general plan, still there are many important deviations in form and arrange- 

 ment from those of the typical animal. The more important of these features 

 we now proceed briefly to consider. 



KUMINANTIA. 

 DIGESTIVE SYSTEM. 



The lips of the ox are thick <id rigid, and having very little mobility, are 

 only indirectly prehensile. A large part of the outer centre of the upper lip 

 is devoid of hair, prolonged between the nasal openings, and constitutes the 

 muzzle. It varies in colour with the animal, but in health is always moist. 

 It is covered with papillae and the orifices of the ducts of subcutaneous glands, 

 which moisten the part with their secretion. The lips of the smaller ruminants 

 are thin, and, being very mobile, are agents of prehension ; the superior one 

 is divided in front by a median fissure. 



The cheeks of ruminants present on their inner surface, between the com- 

 missure of the lip and the first molar tooth, numerous large, long, conical 

 papillse which point backwards. Posteriorly a row of the same runs along the 

 level of the upper molars. Small round papillse are also present. 



The hard palate is large, its posterior third being smooth ; the anterior two- 

 thirds are covered with transverse bars, which do not form arches, but are 

 deiiticulated, the ridges projecting backwards. Behind the pad of cartilage 

 which replaces the upper incisors there is a mark resembling a letter T in the 

 middle line, with the normal directed backwards,' and at each extremity of the 

 transverse line is the buccal opening of Jacobson's canal. 



The soft palate is not so complete and pendulous as in the horse. The 

 isthmus faucium is always open, thus permitting the animal to breathe through 

 the mouth, and allowing the upward passage of food. Some authorities hold 

 that the tonsils are present in ruminants. 



The tongue of the ox being prehensile, its muscles are well developed, and it 

 possesses great mobility.. It is much rougher, shorter, and thicker than in the 

 horse, and pointed at the tip. The papillae are better developed, the filiform 

 being very large and numerous near the apex. The circumvallatse are arranged. 



