STEUCTUBE OF THE HORSE. 



117 



upper lateral incisors, and at this time a groove will be noticed 

 in the upper corner tooth. The groove extends half down down 

 the tooth at fifteen years of age, and reaches the bottom of the 

 tooth at twenty-one. At twelve years of age the table surface 

 of the upper row of incisors is found to be worn smooth. The 

 dental star makes its appearance when the animal is eleven 

 years of age. This is a little spot, located on the table of the 

 tooth, differing from the rest of the dentine. The temporary 

 teeth may be readily recognized bv their small size, their well- 



Fig. 17 — Lower Incisors of an Eight Year 

 Old Horse. 

 1, 1. Cups obliterated. 



2, 2. Cups obliterated. 



3, 3. Cups gone . 



i, 4. Cups worn considerably. 



Fig. is—l'pper Incisors of an Eight Year 

 Old Horse. 



1, 1. Central nearly smooth. 2, 2. Next 

 pair showing a remnant of the cup, 3, 3. 

 Corner incisors showing cup plain 

 enough. 4, 4. Canine teeth worn down 

 more than in the lower jaw of the fix 

 year old mouth. 



marked neck, and extreme whiteness. The permanent teeth 

 are darker in color, have no well-marked neck, and are larger. 

 The permanent incisors of the lower jaw show a well-marked 

 groove on the anterior surface of each tooth that is absent in the 

 permanent teeth. The permanent incisors of the upper jaw 

 each show two of these grooves. The young tooth is broadest 

 from side to side, the tooth of old age being broadest from the 

 front backwards, and gradually growing narrower from side to 

 side. After the animal has reached ten years, it becomes some- 

 what difficult to ascertain his age correctly, but by practice one 



