352 



THE HORSE 



as follows, taking about two months in the process from the 

 time they are first seen. 



Centrals appear, at birth (Plate XI.). 



Middle „ 14 to 21 days, and are level at 2 months (Plate XIV.). 



Central ,, 6 months, „ ,, 8 months (Plate XV.). 



These foal's teeth differ from the permanent ones in being 

 semicircular, with a shoulder, whilst the permanent teeth 

 diminish in size from the crown downwards with a regularly 

 graduated slope. The milk teeth have a short fang, which 

 is gradually absorbed, so that the tooth is ready to fall off 

 when the corresponding permanent tooth is sufficiently 

 ready. But the permanent teeth are of considerable length, 

 are partially curved in shape, and when first developed are 



PLATE XIV. 

 FoaVs Teeth at 2 Months. 



PLATE XV. 



FoaVs Teeth at 6 Months. 



twice as wide as they are thick through (Plate XVIII.). In 

 consequence of their graduated form, as the upper surface 

 is worn away, the width and thickness by degrees alter 

 their respective proportions, until in a very old horse 

 they become twice as thick through as they are wide 

 (Plate XXV.). 



Similarly, from being curved, the lower teeth which were 

 at the beginning perpendicular, become very nearly straight 

 as age creeps on. 



The two central permanent teeth, and the two middle 

 ones in the lower jaw, have grooves down the front from 

 their first appearance ; but not so the milk teeth, which are 

 quite smooth; and this is another aid in distinguishing 

 between them. 



The permanent teeth are thus developed, but often there 



