16 



AGE OF THE DOMESTIC ANIMALS. 



the permanent incisors predisposes the animal to the contraction 



of contagious fevers. 



PERMANENT INCISORS. 



The permanent incisors are six in number in each jaw, like 

 the deciduous incisors which they replace ; they, like the latter, 

 are known as the pincher teeth, intermediate teeth, and corner 

 teeth. They are longer than the milk-teeth, are more of a wedge- 

 shape, have no constriction or neck separating the crown from the 

 root, and are of a bluish-white, instead of the cream color of the 

 others. The permanent incisors (Fig. 7) are shaped somewhat 



Fig. 7. 



A virgin inferior permanent incisor. A, anterior face ; B, posterior face ; C, profile. 



like an irregular cone, of which the base corresponds to tlie crown 

 or free extremity, and the summit to the root or the imbedded 

 extremity. They are curved on their long axis, with tlieir con- 

 vex face in front and their concave face behind, and they are 

 also somewhat twisted on their long axis; the pincher teeth are 

 slightly so, the intermediate teeth more so, and tlie corner teeth 

 sometimes make almost a decided S. The free portion, or 

 crown, is flattened from in front to behind, at the level of the 

 gums the two axes liave about the same diameter, and the 

 root or imbedded portion is flattened from side to side. 



