232 MAMMALIAN DENTITION 



tion of the various orders of Mammals it is almost impossible, 

 because of their greater complexity of form, to avoid seeming 

 to lay especial emphasis upon the molars. The student is there- 

 fore apt to gain the impression that adaptations of these teeth 

 are the most if not the only important changes to be observed 

 in the dentition. If he will pause for a moment to consider the 

 infinite variation in mammalian incisors and to think of the 

 very different modifications required for seizing or gathering 

 according to the particular food habit of the animal, the reader 

 Avill readily realize the enormous importance, as emphasized 

 by Bensley, of incisor modifications in determining the 

 morphological characters of the entire dentition. Perhaps this 

 significance of the incisors is most plainly seen in the Marsu- 

 pials among modern Mammals. We have been able to treat 

 of the Marsupials at greater length than other orders because 

 of the large number of representative stages in evolution of 

 teeth still in existence. Such instances as the Horses and the 

 Rodents will hoAvever present themselves at once as marked 

 examples of adaptation of incisors in association with great 

 modification in the dentition as a whole. 



Finally lest any reader, observing the peculiar molars of the 

 Fruit Bats, should wonder how these can fit in with the view 

 put forward at the beginning of this chapter it must be stated 

 that there is evidence, to show that, though greatly specialized, 

 these have undoubtedly been derived from the typical mam- 

 malian tritubercular tuberculo-sectorial type. 



