96 



however, is nevertheless easily distinguished by 

 its greater transparency and more pearly appear- 

 ance. This peculiarity in the crusta petrosa not 

 unseldom gives to the six year old mouth a darker 

 aspect than is presented by the teeth of the younger 

 animal; and the author, to convey to the reader 

 some idea of this fact, has purposely rendered the 

 incisors of the next representation of the mouth, as 

 they frequently are seen. Such a circumstance, how- 

 ever, will not confuse the judgment. The corner 

 nippers still look young to him who is acquainted 

 with those signs which denote youth in the horse's 

 teeth, and the coloured engraving will convey a fair 

 idea of the aspect they now put on. The corner 

 nipper, in fact, after the fourth year, leads, in a 

 great measure, if it does not entirely sway, the 

 judgment This tooth is sometimes called the shell 

 tooth, on account of its infundibuluni beinof, for 

 the most part, better exhibited and longer retained 

 than in the other incisors. The tables, however, of 

 the other teeth should also receive some attention : 

 those of the centre nippers may exhibit the infun- 

 dibula shallow, or, in certain instances, when the 

 crusta petrosa which lines these cavities is very thick. 



