282 



HISTORY OF THE HUMAN BODY 



much variation. In certain marsupials but one tooth is re- 

 placed, the last upper premolar, this tooth alone constituting a 

 second set, while otherwise the milk set is retained through life. 



A 



B 



FIG. 78. Figures representing diphyodont dentition. 



(A) Dentition of a lion cub of six and a half months. [After WEBER.] Milk 

 dentition functional, replacement teeth still within the jaw and shown as shaded 

 areas. (B) Upper jaw of new-born seal, with replacement teeth almost ready for 

 function. The milk dentition is reduced to useless rudiments cast off immediately 

 after birth. [From HERTWIG, after BURCKHARDT.] 



They are thus almost monophyodont, with a permanent milk 

 dentition, and are in sharp contrast to other monophyodont 



