PLATE IX. 



left 



left 



Kg.l. Kg. 2. 



OrangOUtan (five tubercles) 



Fig. 3. Pig.4 



Man (fiye tubercles) 



right 



left 



Eg.5. Hg.6. 



Man (four tubercles) 



1 



right 



FIRST LOWER MOLAR. 



