632 THE EXTERIOR OF THE HORSE. 



plicated. Besides, the dental sac sends forth into the grooves or notches of the 

 faces, as prolongations, longitudinal folds which continue without interruption 

 with the external papillary system (Fig. 301). 



a i 

 c h. 



FIG. 301. Superior right molar removed from its dental follicle. 

 A. Viewed by its free part : 



a, anterior infundibulum. 



a', posterior infundibulum. 



e, external border of the infundibula. 



i, internal border of the infundibula. 

 c, accessory column of the anterior infun- 

 dibulum. 



B. Viewed by its incased extremity (same letters). 



Each external papilla penetrates, from below upward, into the thickness of 

 the tooth, in the same manner as that which forms the central enamel of an in- 

 cisor tooth. It fills thus a cavity, a veritable infundibulum, at first open at its 

 bottom, and afterwards terminating in a cul-de-sac, when it is completely de- 

 veloped (Fig. SOI, A : a, a'). 



There are two infundibula on the table : an anterior, a, and a posterior, of , 

 absolutely distinct from each other. The cavity of each, almost elliptical, wider 

 from before to behind, is limited by two borders, e, i, of which the external is the 

 more salient. The internal, ?', presents, as a singular peculiarity, a sort of column, 

 c, flattened or depressed, but rather thick, situated towards the middle part of this 

 border, and annexed to the anterior infundibulum. This column is limited by 

 two grooves, </, h ; the posterior, d, forms a sort of re-entering angle forward, and 

 is deeper than the anterior. 



The incased extremity (Fig. 301, H) does not resemble that which we have 

 described. It presents a number of folds whose disposition appears at first sight 

 complicated, and which have been compared with much correctness, by Bracy 

 Clark, to a Gothic V B. 1 



On careful examination, there can be clearly distinguished : first, the bottom 

 of the infundibula, a, a', which we mentioned above, and, around these, an irreg- 

 ular cavity folded upon itself. The latter opens at the incased extremity, but, 

 terminating in a cul-de-sac towards the free extremity, is continued into the ac- 

 cessory column, c, of the anterior infundibulum, a. A superficial observer might 

 be led to believe in the presence of five cavities, namely, two close to the ex- 

 ternal border, e, e, two close to the internal border, ?', i, and, finally, one for the 

 accessory column, c, on the internal face. This would be an error ; in fact, there 



1 Bracy Clark, On the Knowledge of the Age of the Horse by his Teeth, 4to, London, 1826. 

 (See Fig. 8.) 



