156 HIGH SCHOOL ZOOLOGY, 



teeth of the caniivorous (lentition, the canines and sectorials, 

 specially tleveloped in accordance with the carnivorous habits, 

 wliile the asterisk indicates the gap caused Ijy the absence 

 of tlie first premolar. It is interesting to compare this formula 

 with the less specialised dentition of a dog: — 



i i i C pm pm jnn PM m m 

 i i i C pm pm pm m m m 

 Here it is obvious that the last premolar above, and the first 

 molar below are, as in the cat, the sectorial teeth, and although 

 the molars proper are more numerous, they show the same 

 tendency to a riidimentary character at either end of the 

 series. As far as numbers go, the bear's formula is the same as 

 the above, but there is no specialisation of the sectorial teeth, 

 and both the bear and the dog present a formula, which is very 

 near to what is generally considered the typical formula of the 

 Mammalia, only differing therefrom in the absence of a third 

 upper molar. Rewiiting, then, the cat's dental formula after 

 com])aring it with that of the dog, we should have the follow- 

 ing better expression of its dentition. 



j^l p jS c * pYj-j2 pjj^S pjjj4 nxi * * 



p ^j p c * * pm^ pm* M^ * * 

 When it is not considered necessary to indicate the relative 

 ])Osition and character of the teeth, the dental formula is gen- 

 erally simplified ; thus, (for the cat): — if c\ pm| m\. 



In respect to their foi-m, the molai's in the Carnivores 

 hardly deserve the name of grinders, for the functional 

 molars have sharp cutting edges not adapted for grimling. 

 The bears and their allies, however, which are more omnivorous 

 in their habits, show how a cuspidate molar may be worn down 

 to a grinding surface. 



1 2. In most mammals the lips and tongue attain consider- 

 able independence of movement ; this is associated with tlie 

 development of a complicated musculature which is hardly 



