950 VETERINARY DENTAL SURGERY. 



and six months, the first intermediate (internal lat- 

 eral) incisors are shed and replaced by permanent 

 teeth, which are up and in wear at three years. 



The third pair of incisors or second intermedi- 

 ates (external lateral) are shed at three years and 

 replaced by permanent teeth, which are up and in 

 wear at four years old. 



The cutting of the corner incisor is variable, 

 indeed as much so as the canines in the horse, and 

 very little reliance can be placed upon their appear- 

 ance. They may appear anywhere from three and 

 one-half to four and one-half years. They always 

 are up and in wear by the fifth year. All the teeth 

 at this time show worn table surfaces. Dentition is 

 always more advanced in bulls (and the better bred 

 the earlier the process of dentition is completed) than 

 in steers or females. After the fifth year the teeth 

 form no true basis by which to judge the age. If 

 the cattle have horns, the age can be calculated from 

 the appearance of the rings on the horns. For the 

 first two years the rings are so indistinct that the 

 first ring indicates a three years' growth, and by 

 adding one year thereafter for each ring, we get the 

 correct age, so that an animal with four rings would 

 be six years old, an animal with six rings eight years 

 old, and one with eight rings ten years old. 

 DENTITION IN THE SHEEP. 



At birth the lamb is usually without incisor teeth, 



