THE TEETH 



259 



smaller in size than the permanent teeth and somewhat different 

 iu shape. They are more rounded in front, and hollow towards 

 the mouth, the outer edge being at first much higher than the 

 inner. As they wear down, these two edges soon become level, 

 but the corner nippers maintain this appearance for a long time. 

 At six months the central nippers arc almost level, with the black 

 "mark" in their middle wide and faint; and about the ninth 

 month the next nipper on each side above and below is also worn 

 down almost to a level surface. 



During the second year the following changes take place : — ■ 

 In the first month, and sometimes towards the end of the first 

 year, a fourth grinder is cut all round, which commences the set 

 of permanent teeth, the three first molars only being shed. At a 

 year and a half, the mark in the central nippers is much worn out, 

 and has become very faint; the second is also worn fiat, but is not 

 so faint; and the corner nippers are flat, but present the mark 

 clearly enough. In colts which have been reared on corn and 

 much hay, the wearing down proceeds more rapidly than in those 

 fed upon grass alone. 



The third year, is occupied by the commencement of the 

 second dentition, which is effected in the same order in wdiich the 



i-'i.i. 



-THBEB-YEAtt-OLD MO 



B. Anterior maxillary bone. 



1. 1 Central permanent nippers, ne 



full-grown. 



2. 2. Milk teeth worn down. 



4. 4. TuslK 



lillc teeth, still showing cen- 



■k 



ODcealed within the jaw. 



Both sets are contained within 



milk teeth made their appearance. 



the iaw at birth, the permanent teeth being small and only par- 



