THE TEETH OF MAMMALS 171 



is shed in turn. The series are in continual proc- 

 ess of formation and destruction, of shedding and 

 replacement, until the last molar comes into place 

 when the animal is old and remains through the 



Fig. 73. — Teeth of Elephant (species unknown). 



rest of life. The first of the molars is in place at 

 three months, and has but four plates of enamel. 

 The second follows at two years, and has eight or 

 nine plates. The third follows about the fifth 

 year, and has eleven to thirteen plates, and is four 



