THE CHARACTERS FURNISHED BY THE TEETH. 657 



opinion that the horse is over fifteen or sixteen years. We concede 

 that such an opinion from an experienced and sagacious man may at 

 times become a certainty. Nevertheless, we do not think that any 

 one is justified in saying positively how much older than sixteen 

 years the animal is. Those who make this pretension have perhaps 

 succeeded in a few isolated cases ; but, if it were possible to know each 

 time their absolute reasons and their success, their numerous errors 

 would prove that in most instances they are not guided by any positive 

 principle : it is the absence of proof which saves them. In a case of 

 advanced age, prudence will prompt the observer or the expert to do no 

 more than hazard conjectures. All those who, like ourselves, under- 

 take the task of studying the age from authentic mouths of the 

 horse, will soon be convinced of the necessity of caution in making 

 their estimates. We have seen some jaws thirty-five, forty, forty- 

 two, and forty-seven years of age which evidently presented the 

 definite signs of old age. But by examination it was impossible to 

 tell at what age the subjects from which they had been obtained had 

 arrived. 



The characters of this period are : 



1. The successive forms of the free extremity of the incisors. 



2. The disposition of the cul-de-sac of the central enamel in the 

 two jaws. 



3. The form and situation of the dental star upon the tables of 

 friction. 



4. The obliquity or the degree of incidence of the incisive arcades. 



5. The convergence of the teeth by their free jjart, and the small 

 transverse diameter of the same arcades. 



6. The degree of thickness of the peripheral enamel bordering the 

 dental table in front and behind. 



7. The appearance of the radical cement. 



8. The external state of the tooth. 



Nine Years. — The pincers are round ; their central enamel takes a 

 triangular form, and their dental star, narrower but more marked, 

 occupies almost the middle of their tables. The intermediates are 

 becoming round, and the corners are oval. The superior pincers are 

 often levelled. The notch of the superior corners sometimes disap- 

 pears at this age. In profile, the jaws form an ogive, more marked 

 than at eight years. (Plate XXII.) 



Ten Years. — The pincers are still more round ; their central 

 enamel is smaller, distinctly triangular, and approaches more towards 

 their posterior border. 



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