THE HORSE ANATOMY AND 1'HYSIOLOGY. 



027 



in. 



year. Figure I. shows the shape and appear- 

 ance of the face or level of a three-year-old nip- 

 per as it comes through. II. shows same tooth 

 at six years, the crown worn off one-fourth of 

 an inch. It is narrower and thicker than at 

 three years. III. shows this tooth at twelve 

 years. The breadth and thickness are nearly 

 equal, and the crown or face has become nearly 

 round. IV. shows the tooth in an eighteen 

 year-old mouth. Quite oval. V. shows the 

 tooth at twenty-four, the reverse of its condition 

 in the three-year-old mouth. Its depth is greater 

 than its breadth about two-fold. These diagrams 

 give a correct idea of the character of the change 

 going on, and will help to understand the dif- 

 ference between mouths of various ages. 



In the third year the second dentition begins 

 and takes place in the same order in which the 

 milk teeth appeared. During the third year the 

 grinders begin also to be visible, so that by 

 the end of the third year the sixth grinder ap- 

 pears, but grows very slowly. By the middle of 

 the year the nippers show wear on outer edge, 

 and the middle teeth are pushing through. The corner teeth, of 

 remaining foal teeth, are worn down, and the mark has disap- 

 peared in a great measure. 



IV. 



v. 



FIG. 6. CHANGES IN 

 KOKM OK TEETH. 



Fio. ". ADVANCED THKKK-YF.AK-OI.D MODTH. 



By this time the foal teeth are all gone. The nippers show 

 wear on both edges, and the outer edge of middle teeth is worn. 



