192 



ANIMAL BIOLOGY 



b e 



Fig. 342. — Foot of Bear 

 {Plantigrade). 



eaten. The feet vary according to use in obtaining food 

 or escaping from enemies. This will explain the differ- 

 ence in the length of legs of lion 

 and horse, and of the forms of 

 the teeth in cat and cow. Make 

 a careful study of the teeth and 

 limbs as shown in the figures and 

 in all specimens accessible. Write 

 out the dental formulas as indi- 

 cated at the top of page 194. The numerals above the line 

 show the number of upper teeth ; those below the line 

 show the number of lower teeth in one half of the jaw. 

 They are designated as follows : I, incisors ; C, canine ; 

 M, molars. Multiplying by two gives the total number. 

 Which skulls in the chart have the largest canines ? 

 Why ? The smallest, or none at all ? Why ? Compare 

 the molars of the cow, the hog, and the dog. Explain 

 their differences. In which skulls are some of the molars 

 lacking ? Rudimentary ? Why are the teeth that do not 

 touch usually much smaller than those that do ? 



Fig. 243. — Polar Bear (U?sus maritimus). 



