Dissection of Sheep's Head. 221 



Being satisfied that the milk molars are still in place, the 

 next point to note is how many true molars have cut the 

 gum, for 



In the Sheep 



The anterior molar cuts the gum from the third (early) to 

 the ninth (late) month ; the second molar cuts the gum from 

 the ninth (early) to the twelfth (late) month ; and the pos- 

 terior (tri-lobedj cuts the gum from the eighteenth (early) to 

 the twenty-fourth (late) month. 



Hence if, as here, two molars only can be felt, each bilobed, 

 posterior to the trilobed milk molar, you know the sheep to 

 be over nine months and under eighteen months old. But 

 there remains a simpler test of age than this, by referring to 

 the teeth that fringe the anterior margin of the jaw. 



These teeth will be seen to be eight in number, of which 

 the three on each side nearest the middle line are called 

 Incisors ; and the outer one on each side is called a Canine 

 tooth. All this series, in course of development, goes through 

 a process of replacement ; and in this process the teeth assume 

 a difierent shape ; the first set being small and narrow, with 

 an almost circular blunt grinding surface ; the second set 

 broad and large, with a trenchant edge, and brown markings, 

 like two leaves, on the inner surface. The central pair alone 

 represents the permanent series in the case before us. 

 Now in the Sheep 



The permanent central incisors appear from the twelfth 

 (early) to the twentieth (late) month ; the permanent internal 

 lateral appear from the eighteenth (early) to the twenty- 

 eighth (late) month ; the permanent external lateral appear 

 from the twenty- seventh (early) to the thirty- sixth (late) 

 month. The corner pair, or Canines, appear from the thirty- 

 sixth (early) to the forty-second (late) month. 



In this case the central pair of permanent Incisors, com- 

 monly called the Nippers^ being up, and no others, we 



