198 AGE OF THE DOMESTIC ANIMALS. 



the table surface of the incisor teeth. They have no canine 

 teeth, or tushes, in either jaw. He has met with some half- 

 breds that had canine teeth in the upper or the lower jaw, but 

 found no cases with those teeth in both jaws. The molars vary 

 in number and relative position in different animals. The de- 

 \ elopment of the adult dentition is much slower and later than 

 in other classes of dogs. 



One Mexican hairless dog, aged 2 years, had five superior 

 incisors, no canine teeth, two superior molars on each side, one 

 large molar and one very small molar behind the large one ; 

 two inferior incisors, no canine teeth, two inferior molars on 

 each side, one large molar and one very small molar behind the 

 large one. Total number of teeth, 15. 



A Mexican hairless bitch, aged 2 years, had four superior 

 incisors in front and one on right side midway between the front 

 teeth and the molars, no canine teeth, two superior molars on 

 each side, one small molar and one large molar behind the 

 smaller one ; seven inferior incisors in front, and two on each 

 side midway between the front teeth and the molars, no 

 canine teeth, two inferior molars on each side, one large molar 

 and one small molar behind the large one. Total number of 

 teeth, 24. 



DETERMINATION OF AGE BY THE TEETH. 



From the evidences furnished by the teeth the age is divided 

 into three periods : — 



1. Eruption of the temporary teeth. 



2. Eruption of the permanent teeth. 



3. Wearing of the permanent teeth. 



ERUPTION OF THE TEMPORARY TEETH. 



At Birth. — Puppies may be born with all of their temporary 

 teeth, but if the teeth have not appeared the eruption commences 

 at once by the incisors and tusks of the upper jaw, and the entire 

 dentition is effected within the first three weeks at the longest. 

 (Fig. 179.) 



