38 



/-: TE /,v A\ i /i 1 r />/; .v y. i 



i '. 



in wear at four years. The corner incisors are replaced 

 by permanent ones at three years and nine months, 

 and are up and in wear at four years. 



FIG. 9. 



THE TEETH OF THE ox. 



i, upper jaw with , the friction surface and 

 b, the external surface ; 2, lower jaw with <?, the 

 dental tables, and b, the external surface. Chan- 



