DETERMINATION OF AGE BY THE HORNS. 171 



almost forms a straight line. The teeth appear to separate, and 

 the gum shows between them. 



FIFTH PERIOD WEARING AWAY OF THE CROWNS. 



From this time on there is a progressive change in the 

 shape of the teeth ; the crowns become worn down with more or 

 less rapidity, they diminish in si^e, the dental stars become 

 larger and square, the teeth seem to separate, and the retracting 

 gum leaves the yellow roots uncovered. 



At ten years the dental star is square in the pinchers, and 

 the first intermediate and the corner teeth are leveled. 



At eleven to twelve years the dental star is square in all 

 of the teeth, which become triangular in shape and commence 

 from this time on to be worn to stubs. (Fig. 167, a.) 



It must always be borne in mind that the race of the an- 

 imal and the character of the food produce great variations in 

 the wearing of the teeth. Animals fed on hard forage and 

 those fed on brewers' grains will have their teeth worn down 

 much more rapidly than those fed on the prepared food of the 

 ordinary dairy. 



DETERMINATION OF AGE BY THE HORNS. 



The horns of cattle, rising more or less gracefully from the 

 frontal bones, were undoubtedly intended for weapons of offense 

 and defense. All breeds of cattle are provided with horns, 

 except that known as the angus or polled angus, which was 

 indigenous to the northern part of Great Britain from the earliest 

 historical times, but of which we have no trace in prehistoric 

 deposits. Among all varieties of cattle individuals may be de- 

 void of horns ; they are known as " muUey," or, if deprived of 

 their horns artificially (dehorned-dishorned), are called " polled." 



Polling has been done by the Hindoos for over the last 

 two thousand years, without ever showing trace of producing 

 hereditary results. 



The horns are symmetrical in shape, and when there is 



