736 THE EXTERIOR OF THE HORSE. 



hardness of the dental tissues, to the nature of the aliment, or, again, 

 to their state of soundness ; but the first of these causes is by far the 

 most common. 



Like the beguile, it is frequently observed and in a very irregular 

 manner. Sometimes it exists only upon a few of the teeth, at other 

 times in all, on one side of the incisive arcade only, or in both at the 

 same time. 



Whatever may be its forms, it is never a serious obstacle to the de- 

 termination of the age. While its presence, at first sight, would indicate 

 the horse to be younger, an attentive examination of the dental table 

 its particular form, the configuration and the situation of the dental 

 star, the state of the superior incisors, the direction of the teeth, their 

 length, their coloration, etc. will furnish many signs, easily appreciable, 

 and which will prevent us from committing a grave error. 



6. Irregularities through Defect of Length or Excess of Width 

 of one of the Jaws. 



A. Defect of Length of one of the Jaws. We have seen and also 

 possess some specimens of this very rare anomaly. Their variable degrees per- 

 mit us to establish some important distinctions as respects their gravity. 



In the mildest cases there is found a slight diminution of length of the su- 

 perior jaw, which occasions a prominence of the inferior incisors and simulates 

 somewhat the prognathlsm of man, in which the inferior jaw appears longer than 

 the superior. The only unfavorable effect of this form of jaw is an abnormal 

 wear, rendering the "determination of the age more difficult. 



In all the more serious cases (Figs. 317 and 318), on the contrary, it depends 

 upon an arrest of development of one of the jaws, to which can be applied the 

 name brachygnathism l (superior and inferior), because, in fact, the jaw which is 

 affected is shorter than the other. 2 



Such a disproportion of length has a definite importance in that which 

 concerns : 1st, the deformity of the opposite jaw, which is curved more or less 

 forward than normal ; 2d, great difficulty in the prehension of food, especially 

 in horses feeding on pasture ; 3d, finally, an absolute obstacle to the determina- 

 tion of the age. 



Brachygnathism is superior (Fig. 317) or inferior (Fig. 318) ; the former is 

 more rare than the latter. The incisors, in both cases, are of great length. As 

 to the molar arcades, they are normal. The malformation, therefore, only alters 

 the dimensions of the superior or inferior interdental spaces. 



When the incisors still touch each other, the wear due to the friction involves 

 their contiguous faces, and produces here, ordinarily, a very oblique bevelling. 



1 From /SpaxCs, short, and yvaflos, jaw. 



2 It will be remarked that superior brachygnathism, for example, is accompanied by inferior 

 prognathism, more or less marked, and vice versa. 



