84 COMPARATIVE DENTAL ANATOMY 



There are examples, however, of milk teetli which 

 have no successors, as some Rodent incisors, and 

 of permanent teeth which have no deciduous pred- 

 ecessors, as the true molars. Some Rodents — 

 as the rat — have hut one set and are monophyo- 

 dont. The elephant's molars succeed each other 

 continuously from behind by lateral displacement. 

 The Carnivora have a well-developed milk set. 

 The Herbivora have also a milk set, but the true 

 molars arise de novo. In the Quadrumana the 

 two sets are similar to those of man. 



