of the Animals of tJie Farm. 51 



wear ; the central incisors especially will be worn hollow on their 

 upper surfaces, the middles and laterals also showing well- 

 marked tables in the place of sharp cutting edges ; while the 

 recently cut corner incisors, supposing their eruption to have 

 been delayed till the sheep was nearly four years old, will pre- 

 sent a marked contrast to the rest of the teeth which have 

 suffered from attrition. These appearances are shown in the 

 next drawing (Fig. 50) of the mouth of a sheep at the age of 

 four years. 



Fig. 50. — Incisors of Sheep atfotir years 



After the age of four years, and indeed from the time of the 

 completion of permanent dentition, whether early or late, the 

 changes which are effected in the form of the incisors by wear 

 vary according to the nature of the food, and the examiner must 

 be content to limit his inquiries to the period within which is 

 comprised the eruption of the permanent teeth. 



Dentition of the Pig. 



When dentition is perfect, the pig has six incisor teeth in 

 the front of both upper and lower jaw — two central, two lateral, 

 and two corner teeth. Behind the corner teeth are the tusks, 

 one on each side, in the upper and lower jaws. Between the 

 tusks and the molar teeth there are usually four small teeth 

 which are described as pre-molars, one on each side of both jaws, 

 and twenty-four molars, six on each side of the upper and lower 

 jaws. 



Temporary and permanent incisors agree generally in number, 

 form, and position, but the temporary molars are onl^ three 

 in number on each side of the upper and lower jaws, and the 

 third molar has three cusps instead of two. The temporary 



