660 THE EXTERIOR OF THE HORSE. 



lateral surfaces ; the dental star shows itself here by a white spot, or in 

 some very old horses by a small cavity, which occupies their centre ; 

 the incisive arcades are almost effaced, rectilinear, and very narrow in 

 the transverse sense. 



The peripheral enamel is incomplete ; it is often wanting behind ; 

 at other times no traces of it are found in front. When it has totally 

 disappeared, the radical cementation takes its place (Fig. 286), sur- 

 rounds and consolidates the incisive stumps into their cavities, at the 

 same time that it increases the surface of the dental tables. As this 

 layer of enamel wears off, there are seen through its thickness the 

 striae of the subjacent dentine, provided always that there is no 

 superficial cementous formation. 



The canines, either the superior or the inferior alone, or both simul- 

 taneously, are always very much worn. As to the molars, they are 

 ordinarily very irregular. 



Finally, the tongue protrudes beyond the bars ; the narrowness of 

 the lingual canal causes a flow of saliva when the jaws are separated ; 

 the mucous membrane is wrinkled, less vascular, and adherent to the 

 bone ; the inferior border of the maxillary bone is altogether sharp 

 and the lateral sides of the face hollowed. 



The general aspect of the horse also furnishes other signs : the 

 temples and the supra-orbital arches are gray ; the hairs of the mane 

 and the tail have fallen out ; the head and the body are emaciated ; the 

 axes of the members lose their regularity, the articulations their neat- 

 ness and their mobility, the movements their ease ; in a word, the 

 practised observer recognizes quite easily upon the organism which he 

 views the signs of degeneration, fatigue, and wear. It is by an intel- 

 ligent deliberation and comparison of these numerous characters that 

 one can form an opinion relatively near the truth. 



The fact remains, without contradiction, that numerous researches 

 have yet to be made upon all questions which pertain to a more 

 exact determination of the age of the horse. Those of our profes- 

 sional brethren who are able to conduct them will have deserved well 

 of science if they are willing to publish their results. 



Before passing on to the study of the irregularities of the dental 

 system, we will request the reader to read the explanatory legends of 

 the plates to which we have referred him in this chapter, and which, 

 by reason of their dimensions, we have not been able to insert com- 

 pletely into the text. If he familiarizes himself thoroughly with the 

 characters which he should recognize, it will be more easy afterwards 

 for him to apply them upon the living animal. 



