Teeth of Mammals. 77 



generally long and pointed and has but one root. 

 To it the name canine is given, while the other 

 maxillary teeth have in general two or more fangs, 

 and are called grinding teeth or molars. The milk 

 teeth are usually fewer than the permanent teeth, and 

 hence some of these grinders have had predecessors 

 while others have not; those which are secondary 

 are called premolars, while those which are primary 

 (the hindermost), are called molars. Similar names 

 are given to the corresponding teeth in the lower jaw. 

 As the teeth vary in number and size in the different 

 orders of mammals, they afford a good and easy 

 system whereby the different forms can be discrimi- 

 nated ; and in order to be able briefly to describe the 

 characteristic dentition of any animal, zoologists are 

 in the habit of tabulating the number and arrange- 

 ment of the teeth of animals in a set formula ; thus 



FIG. 35. 



Teeth of Tasmanian devil. 



to write the dental formula of an animal we first put 

 down the initials of the sets of teeth, and follow each 

 initial by the number of teeth of that sort in the two 

 jaws, those of the upper jaw being written like the 



