18 



her a perfect tush, by the presence or absence of 

 which, the sex is indicated by the mouth, and upon 

 which castration appears to exercise no influence, 

 since the gelding- has as well-formed a tush as the 

 perfect male. The molars are ranged in companies 

 of six, one company on either side of the upper, and 

 a like number similarly situated in the lower jaw. 

 The molars are the instruments which enable the 

 horse to grind down the fibrous and hard food upon 

 which it subsists, and they are distinguished by their 

 locality, as first, second, third, fourth, fifth, or sixth 

 molar tooth of the near or off side in the upper or 

 lower jaw ; the first being that growing in front, or 

 nearest to the incisoi's, and the sixth that placed most 

 backward in the cavity of the mouth. 



10. Three substances enter into the compositi07i of 

 the horses tooth. Each of these substances is distinct, 

 and can be distinguished from either of the others. 

 The names given to the various parts are — 1, crusta 

 petrosa, or hard crust ; 2, enamel ; and 3, ivory. 



11. The crusta petrosa is the most externally situ- 

 ated, and when the tooth first appears in the mouth, it 



