BEASTS OF PREY 29 



(6) The dentated edges of these shear blades prevent the object to be 

 cut up from slipping out. 



(c) As the premolars fit into each other and the carnassials glide past 

 each other, the crowns of these teeth do not wear away (as in herbivorous 

 animals), and the teeth, so far from becoming blunt, actually sharpen each 

 other mutually. 



; (d) The position of the carnassial teeth far back in the short jaws, 

 i.e., on the much shorter arm of a lever, still further intensifies their action. 

 For, by the principle of levers, the shorter the arm on which the load 

 acts, the greater is the effect of the power. Owing to the shortness of 

 the jaws, the other teeth also rest on the short arms of levers, and can 

 accordingly exert a powerful action. The rounded, globose head of the 

 cat therefore stands in the closest relation to its mode of life. (Compare 

 the head of an ox.) 



(e) To keep the blades of the shears in a position most effectual for 

 working, it is necessary that the shears be tight in their rivet. Conse- 



Skull of Domestic Oat. (One-half natural size.) 



quently the joints of the lower jaw are very firm. Their sockets are deep 

 transverse grooves, in which the roller-shaped heads of the mandible 

 can only turn about their axes. The mandible is thus only capable of an 

 up-and-down motion, not of a lateral or forward movement, as is the case 

 in ruminants and rodents (which see). 



3. Behind the upper carnassial teeth we find on each side a small 

 tooth with blunt prominences (molar tooth), which, as its grinding 

 surface shows, serves to crush the food. An inwardly directed projection 

 of the upper carnassial has a similar signification. 



4. These arrangements, however, are not sufficient for the thorough 

 rubbing or crushing up of the food (see Section 9). In its tongue, which 

 is provided with many sharp, backwardly-pointed spines, the cat possesses 

 an additional instrument of attrition. Indeed, it furnishes the mouth 

 with, as it were, an additional weapon. (Thus, the largest of the cats, 

 ihe lion, can by repeated licking cause the skin of a man to bleed.) 



5. The incisors, as one might gather from their small size, are not 



