IRREGULARITIES OF THE DENTAL APPARATUS. 



743 



characters of the wear are the opposite of those of an ordinary parrot 

 mouth. Here it is the posterior face of the lower pincers which 

 becomes bevelled as a consequence of the prolonged friction against the 

 upper incisors. The difficulty in the prehension of food and in the 

 determination of the age are of the same order as in the opposite 

 anomaly ; the discrepancy, in this case, is also remedied by the same 

 operation. 



d. Excess of Length of some Teeth alone in both Jaws. 

 — This disposition is, so to speak, only a necessary consequence of the 

 preceding. It will suffice to mention it. 



In certain horses the inferior pincers, intermediates, and corners on 

 the left side, for example, are very short, while the corresponding teeth 

 of the superior jaw are very long. In the right half of the incisive 

 arcade there is a contrary disposition. Whatever may be the seat and 

 nature of this anomaly, the wear of the teeth in both jaws is always 

 inversely proportional. If such a horse be examined with a view 

 of determining his age, it is found that one side evidently appears 

 older, than the other. To make a proper estimate, it suffices to take 

 the mean of the signs furnished by each side separately. 



/?. Insufficient Length of the Crown. 



The irregularities due to this cause also involve both jaws ; such 

 examples, somewhat rare, are peculiar exclusively to old horses. In 

 such deformities, save in horses that are cribbers, the teeth of the 

 opposing arcade are always too long. 



In specimens which we have before us while writing these lines, 

 the superior pincers measure only 0.004 m., the intermediates 0.005 m., 

 and the corners 0.009 m. from their anterior border to the gums ; while 

 in the inferior jaw we estimate in the same order 0.032 m., 0.030 m., 

 and 0.028 m. 



In the jaws belonging to another subject, but in which the defect 

 of length existed in the teeth of the inferior jaw, we found (Fig. 321) : 



Superior Jaw (RigM) : 



Pincer 0.031 m. 



Intermediate 0.031 m. 



Corner 0.024 m. 



Inferior Jaw {Sight ) : 



Pincer 0.001 m. 



Intermediate 0.007 m. 



Corner 0.001 m. 



Very often the defect in the length of the free part coincides with 

 that of the incased part, as can be seen in the figure. However this may 

 be, the state of the dental table — by its form flattened from one side to 

 the other, and by the abundance of the radical cementation — always 



