THE SKELETON OF THE DOG. THE TEETH. 377 



premolar forms a compressed ridge, and at the antero-internal 

 edge of the tooth there is a small inner tubercle. 



The two molar teeth are of very unequal size. The first, 

 which has two anterior roots and one posterior, is wider than 

 it is long, its outer portion being produced into two prominent 

 cusps, while its inner portion is depressed. The second molar 

 is a small tooth resembling the first in its general appearance, 

 but with much smaller outer cusps. 



Teeth of the lower jaw. 



The three incisors of the lower jaw have much the same 

 character as the first two of the upper jaw ; while the canine 

 is identical in character with that of the upper jaw. 



The four premolars gradually increase in size from the 

 first to the last, but none are very large. The first premolar 

 is a single-rooted tooth resembling that of the upper jaw ; the 

 second, third and fourth are two-rooted, like the second and 

 third of the upper jaw, which they closely resemble in other 

 respects. 



The first molar forms the carnassial (fig. 84, V), and with 

 the exception of the canine, is much the largest tooth of the 

 lower jaw ; it is a two-rooted tooth, with a long compressed 

 bilobed blade, and a posterior tuberculated talon or heel. The 

 second molar is much smaller, though likewise two-rooted, while 

 the third molar is very small and has only a single root. All 

 the teeth except the molars are preceded in the young animal 

 by temporary milk teeth. These milk teeth, though smaller, 

 are very similar to the permanent teeth by which they are 

 ultimately replaced. 



II. ENDOSKELETON. 

 1. THE AXIAL SKELETON. 



This includes the vertebral column, the skull, and the ribs 

 and sternum. 



