388 DIGESTIVE SYSTEM OF THE OX 



progressively increase in size from before backward. This feature is so marked 

 that the first tooth is quite small, and the space occupied by the first three (i. e., 

 the premolars) is only about one-half of that required for the posterior three 

 (i. e., the true molars). The enamel folds stand out even more prominently in 

 relief on the masticatory surface than in the horse. The occurrence of wolf-teeth 

 is rare. 



The formula of the deciduous teeth is: 



¥ 



(0 3\ 

 Di- Dc - Dp- I 

 4 3/ 



20 



TABLE OF AVERAGE PERIODS OF ERUPTION OF THE TEETH IN THE OX 



Teeth Eruption 



A. Temporary: 



First incisor (Di 1) ] 



Second incisor (Di 2) I t)- -i . o i 



Third incisor (Di 3) [ Birth to 3 weeks. 



Fourth incisor (Di 4) J 



First cheek tooth (Dp 1) Birth to 3 weeks. 



Second cheek tooth (Dp 2) ^ t^- i, 



Third cheek tooth (Dp 3) j ^^^^'^ to few days. 



B. Permanent: 



First incisor (II) 1 3^2 to 2 years. 



Second incisor (12) 2 to 2J/2 years. 



Third incisor (13) 3 years. 



Fourth incisor (14) 33^ to 4 years. 



First cheek tooth (PI) 2 to 23/^ years. 



Second cheek tooth (P 2) 13^ to 2^ years. 



Third cheek tooth (P 3) . . ;• 23^ to 3 years. 



Fourth cheek tooth (M 1) 5 to 6 months. 



Fifth cheek tooth (M2) 1 to 13^ years. 



Sixth cheek tooth (M3) 2 to 2i^ years. 



The eruption of the permanent teeth is subject to great variation. The above 

 figures are the average of observations of improved breeds under favorable condi- 

 tions. 



THE SALIVARY GLANDS 



The parotid gland is smaller than that of the horse, and is light red-brown in 

 color. It has somewhat the form of a very narrow long triangle, and lies chiefly 

 on the posterior part of the masseter muscle. The thick wide upper end partly 

 covers a large subparotid lymph gland. The small lower end is bent forward and 

 fits into the angle of union of the jugular and external maxillary veins; it lies on 

 the submaxillary gland. The parotid duct leaves the lower part of the deep face; 

 in its course it resembles that of the horse, l^ut it pierces the cheek opposite the 

 fifth upper cheek tooth. 



The submaxillary gland is very large, and is pale yellow in color. It is covered 

 to a small extent by the parotid. Its general form resembles that of the horse, 

 but its low(>r (or antei'ior) end is large and rounded, and is sei)arated by a small 

 interval only from the gland of the other side. This part can be distinctly felt in 

 the living animal, and is related externally to a large submaxillary lymph gland. 

 The duct leaves the middle of the superficial face of the gland, crosses the stylo- 

 hyoideus and the intermediate tendon of the digastricus, and is then disposed as 

 in the horse. 



The sublingual gland consists of two parts. The dorsal part (Glandula sub- 

 lingualis parvicanalaiis) is long, thin, and pale yellow in color. It extends from the 

 anterior pillar of the soft palate about to the symphysis of the jaw. It has numer- 

 ous small tortuous ducts (Ductus sublinguales minores), which open between the 

 papilliB under the side of the tongue. The ventral part is shorter and thicker, and 



