180 AGE OF THE DOMESTIC ANIMALS. 



animal may be thirteen or fourteen months before the first two 

 permanent teeth have appeared, while the more hasty, common 

 animal may have its permanent teeth by the same time. In 

 the male the eruption takes place very slightly earlier than in 

 the female. 



The conditions of the points on the fourth and fifth molars 

 already alluded to will aid in deciding- if the eruption has been 

 hasty or tardy. 



Eighteen Months (Fig. 168, II). — At a year and a half 

 the first intermediate permanent incisors and the sixth permanent 

 molars appear. Tlie eruption of these teeth is followed very 

 shortly by the falling out of all the temporary molars, which 

 are replaced almost simultaneously by tlie permanent molars. 

 After two years the molars furnish but little indication of the 

 age. From this time, according to its sex, the lamb takes the 

 name of ram or eive. 



Two Years and Three Months (Fig. 168, III). — About 

 nine months after the eruption of the first intermediate teeth 

 the second intermediate appear ; whether in precocious or tardy 

 races, the interval between the eruption of the first and second 

 intermediate teeth is some tliree months longer than that be- 

 tween the former and the pincher teeth. In tardy animals, in 

 which the first intermediate have not appeared until they are 

 nearly two vears of age, the second intermediate may be delayed 

 until two years and nine months. 



Tliree Years (Fig. 169, IV). — At three years the erup- 

 tion of tlie corner teeth takes place, although under the condi- 

 tions given above certain animals may be several months late 

 in completing their dentition. 



A greater irregularity is found in regard to the appear- 

 ance of the corner teeth than in the sequence of eruption 

 of the others. By the time of the appearance of the corner 

 teeth the pinchers and first intermediate may become worn 

 and even leveled. Girard first noted that some sheep have 

 but six incisors, the corner teeth remaining aborted under the 

 gum. 



