AGE OF THE ASS, MULE, AND HINNY. 



To determine the age of the ass, mule, and hinny requires 

 an extension of the rules which have been applied to the horse. 

 In the young animal the eruption of the milk-teeth and their 

 replacement by the permanent teeth are about the same. 



In these animals the incisors are smaller and narrower 

 and less conical in shape than in the horse. The crown of the 

 teeth is much longer and the root is shorter. The dental cup 

 is continuous until a late period of life, as it is proportionately 

 deeper. The cups are often imperfect behind. As the teeth 

 are harder and more resisting, they wear much slower, and con- 

 sequently the tables change their form more slowly. The teeth 

 are more solidly imbedded in their alveolar cavities, and an 

 excess of gum fixes them firmly. The dentine is more discolored 

 and darker ; the whole tooth is harder and resists the wear of 

 dense, fibrous food better than that of the horse, and consequently 

 does not wear so fast. The form of the tables is of less value, 

 while the form of the arch and the obliquity of the teetli are more 

 important. After seven years the elongated teeth and their ap- 

 proach to each other in a horizontal line, with thinning of the 

 maxilla and the deposit of cement, the dark color and the nar- 

 rowing of the incisive arches, are evidences of age. 



The dental tables change from a round to a triangular 

 form, which is complete at seventeen or eighteen years. At this 

 age the cups may disappear and be replaced by the dental stars. 

 The incisors become parallel to the maxillary bones and con- 

 verge at their free extremities in very old age. 



(157) 



