Masterpieces of Science 



cement, which fills up the valleys, as in the 

 upper grinders. 



If the grinding faces of an upper and of a 

 lower molar of the same side are applied to- 

 gether, it will be seen that the opposed ridges 

 are nowhere parallel, but that they frequently 

 cross; and that thus, in the act of mastication, 

 a hard surface in the one is constantly applied 

 to a soft surface in the other, and vice versa. 

 They thus constitute a grinding apparatus of 

 great efficiency, and one which is repaired as 

 fast as it wears, owing to the long-continued 

 growth of the teeth. 



Some other peculiarities of the dentition of 

 the horse must be noticed, as they bear upon 

 what I shall have to say by and by. Thus the 

 crowns of the cutting teeth have a peculiar 

 deep pit, which gives rise to the well-known 

 "mark" of the horse. There is a large space 

 between the outer incisors and the front grind- 

 ers. In this space the adult male horse 

 presents, near the incisors on each side, above 

 and below, a canine or "tush," which is 

 commonly absent in mares. In a young 

 horse, moreover, there is not unfrequently 

 to be seen, in front of the first grinder, a 

 very small tooth, which soon falls out. If this 

 small tooth be counted as one, it will be found 

 that there are seven teeth behind the canine 

 on each side; namely, the small tooth in 

 question, and the six great grinders, among 

 which, by an unusual peculiarity, the fore- 

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