TEETH IN THE SHEEP. 137 



change eighteen months after birth ; the incisor on each side of 

 these comes out as early, but does not change till thirty months 

 after birth ; the third incisor, on each side, comes out about 

 fourteen days after birth, and changes at forty-two months 

 after birth ; the fourth, or corner incisor, on each side, comes 

 out from six to nine months after birth, and changes about 

 fifty-four months after birth. The three milk molars on each 

 side of each jaw come out before or a few days after birth, and 

 are shed, the first at eighteen months after birth, the second at 

 thirty-two months after birth, and the third at forty months 

 after birth. The first permanent molar comes out from six to 

 nine months after birth, the second at thirty-two months after 

 birth, the third does not come out till the fifth year of the 

 sheep's age. 



In the teeth of the sheep, enamel, cement or petrous crust, 

 and dentine, occur as in the horse and in the ox, and the 

 arrangement therein of these three substances is so similar to 

 that already fully described under the title " Teeth of the 

 Horse" (p. 13), that it would be a waste of time to go 

 over the subject again. The same remark applies to all the 

 other particulars of interest in regard to the teeth of the 

 sheep. 



The roof of the mouth in the sheep, as in man, is formed 

 by the upper jaw-bone and the palate-bone on each side ; 

 while, however, it differs from the human structure in having 

 immediately behind the upper lip the intermaxillary bone, 

 made a pair under the name of anterior maxillaries. In the 

 sheep, as in other ruminants, the intermaxillary bone differs 

 from the corresponding bone in the horse by being destitute 

 of upper incisor teeth. The superior maxillary bone in the 

 sheep has extensive connections entering into the nose and the 

 orbit as well as into the mouth. As in the horse, and as 

 in the ruminants in general, it is comparatively short, but 



