DENTITION AND DENTAL DISEASES 253 



The teeth in shape are similar to those of the cow, but very much 

 smaller. 



370. Incisors. — From the birth of the lamb to the end of the 

 fourth week the six temporary incisors and the two canine or 

 corners are cut, also the first, second, and third temporary or pre- 

 molars ; and at twelve months the crowns of the incisors are well 

 worn, the teeth being small and far apart. At about fifteen months 

 the two central temporary incisors are shed and two permanent teeth 

 take their place. At about twenty-two months the middle laterals 

 (incisors) are replaced by two more permanent teeth, and the animal 

 now has four broad teeth. At two years or two years and three 

 months the permanent laterals make their appearance, and the sheep 

 shows six broad teeth, and at three years old the corner or canine 

 permanents are up. 



371. Molars- - About the age of three months the first per- 

 manent molar, or fourth tooth, makes its appearance ; at nine 

 months the fifth tooth, or second permanent molar, is seen, and at 

 eighteen months the sixth tooth, or last permanent molar, comes 

 into view ; and from twenty to twenty-two months old the first and 

 second temporary premolars, above and below, on each side, are 

 replaced by permanent teeth, and at about two years old the third 

 temporary is shed, and a permanent tooth takes its place, the sheep 

 now having twenty-four permanent molar teeth — viz., J premolars, 

 § molars on each side, and in some early mouths possibly six per- 

 manent incisors. The permanent teeth, both incisors and molars, 

 are much larger and darker in colour than the temporary ones. 



PIG. 



372. The dentition of the pig differs a good deal from that of the 

 cow and sheep. Pigs have six incisor teeth above and below in 

 front of the jaws ; behind the corner teeth on each side in the upper 

 and lower jaws are the canine teeth, or tusks ; and between the latter 

 and the first premolar teeth, one on each side, both above and 

 below, are the anterior premolars ; while there are six molars on 

 each side, above and below — viz., three premolars and three molars. 



