152 COMPARATIVE ANATOMY AND PHYSIOLOGY. 



dentine ;* as lias already been said, these two tissue 

 differ greatly in hardness ; they will, therefore, wes 

 down unequally and so give rise to a roughened su 

 face well adapted for grinding. In addition to tl; 



Fig. 67. Teeth of Wolf. 



i 1 to i 3, Incisors ; c, canine ; p 1 to 4, preraolars ; m 1 to TO 3, molars ; h, he 

 of the first molar or lower " carnassial" tooth. 



outer investment of cement, we find it also filling u 

 the interspaces (Fig. 68). In the Garni vora th 

 lower jaw is so articulated to the skull as to lc 

 able to work from below upwards ; in the herbivoroi; 

 forms the jaw works from side to side. 



Some of the Cetacea (dolphins, whales) are dii 

 tinguished by the total absence of teeth, and th 



* For an account of the minute structure of the teeth, s< 

 Klein's "Elements of Histology," chap. xxi. 



