174 ON THE AGE OF THE HORSE, 



process as the lower teeth, except with this dif- 

 ference, namely, that they do not begin to fill 

 up until all the lower teeth are deprived of their 

 marks, and that there is an interval of two years 

 between every tooth in the upper jaw, whereas 

 in the lower jaw the interval is only one year. 

 Thus, at eight the cavities of the two middle 

 teeth of the upper jaw begin to fill up. Vide 

 fig. G. At ten, the cavities of the two next. 

 Fig. H. And at twelve, the cavities of the 

 corner teeth are totally effaced. Fig, I. This 

 rule, however, is subject to some variation in 

 different horses, in proportion with the different 

 qualities of their teeth, or on account of the 

 habit of crib-biting, which wears away the 

 teeth much faster than in their natural course. 

 In addition to these appearances of the teeth, 

 other signs of advanced age may be discovered, 

 among which the following are the most re- 

 markable : The roof of the mouth or palate is 

 constructed with transverse ridges from one side 

 to the other. Vide fig. G, H, I. These ridges 



are 



