IRREGULARITIES OF THE DENTAL APPARATUS. 



727 



roots, which were united at their points for a distance of one and one-half 

 centimetres. The nerves and blood-vessels penetrated through the roots into the 

 two pulp cavities by means of a single orifice ; the alveolus was single. 



4. Irregularities in the Form of the Central Enamel. 



a. Fissure. We know that the central enamel circumscribes the parietes 

 of a conical cavity, depressed from before to behind, which is entirelyiHolated 



FIG. 315. Fissure of the infundibulum of the inferior intermediates and corners, as well as of 

 the left superior corner (horse). 



from the peripheral enamel upon the surface of friction. This is not always 

 so, as we have verified by observation a large number of times, but more often 

 in the ass and mule than in the horse. 



It happens, in fact, that the posterior border of the incisor, less developed 

 than usual, fails to close the external dental cavity behind ; whence it follows 

 that the free extremity of this tooth, beginning at its anterior border, simulates a 

 hollow surface, oblique downward and backward (inferior incisors), which can, to 



