KINE TOGENESIS. 



345 



the canines are large and the molars few. In the 

 Plagiaulacidae a similar relation is seen between the 

 development of the incisors and the reduction in num- 

 ber of the molars. This is the modification of relation 



observed in existing Mammalia of the orders Probos- 

 cidia and Glires, which will be mentioned later, under 

 the head of proal dentition. 



e. Origin of the Dental Type of the Glires. 



The peculiarities of the rodent dentition consist, as is 

 well known, in the great development of the incisors ; 



