of the AnimaU of tJie Fmm. 87 



the observation of tlie state of the dentition between the asfes 

 of one and six months, when the fourth molar is cvit ; but during 

 this period the jaws expand, the incisor teeth gradually become 

 less crowded, and the space between the third molar and the angle 

 of the jaw increases as the fourth molar, which is the first per- 

 manent tooth, advances to occupy its place, as shown in Fig, 30. 



At the age o^ six months the fourth molar is well developed, 

 but it is in close contact with the angle of the jaw, and the pos- 

 terior surface is not quite free from the covering of the gum. 



Between six o.nd twelve months old there are no important 



Fig. 31. — Incisors of Steer at one year. 



-dental changes, the incisor teeth become worn, and as the jaws 

 increase in size there is more space left between them ; but it 

 is not possible to assert from the states of the incisor teeth 

 whether an animal is under or over the age of one year. 



The illustration above (Fig. 31) represents the average 

 state of the incisors at the age of one year. 



Shortly after one year the fifth molar begins to make its 

 appearance, and at fifteen months it is well np. The appear- 

 ance which the fifth molar presents at this age is very much like 

 that of the fourth molar at the age of six months. The new 

 tooth is in close contact with the angle of the jaw, and the gum 

 covers the extreme posterior part of its surface. These appeai'- 

 ances are shown in the illustration on next page (Fig. 32). 



