338 
On the Teeth of the Ox, Sheep, and Piij, 
Fig. 36* 
wear. Much of their condition, therefore, at this time, will dc- 
j)cnd on the food and management of the animals. 
Although the fifth molar does not differ in any essential particu- 
lar from the fourth, I have thought it right to insert an engraving 
representing the cutting of this tooth, that each stage in the pro- 
gress of dentition may be recorded in the way best suited to 
im])ress the facts on the memory. 
Both the fourth and fifth . molar teeth consist of two main 
parts or lobes blended together, as seen in fig. 36. Each tooth, 
therefore, when first cut, has four cusps of enamel, of which 
the inner are always the highest in the loiocr teeth, and the 
outer in the upper. It is, however, to be remembered that the 
points of these cusps are soon 
worn away, and that consequently 
each of them is thus made to form 
two ridges of enamel, and thereby 
to give to the tooth eight instead 
of four elevations of this sub- 
stance, of varying height. It is 
somewhat necessary that these 
things should be repeated in this 
place, because the degree of wear 
of the teeth is one of the means 
by which the judgment is often 
assisted ; and this is shown by 
the distance which intervenes be- 
tween the external and the central 
ridges of enamel. The value of 
this fact will be seen the more 
when I state that the animal now 
passes nine months of his lile 
without any addition being made 
to the number of his teeth, the sixtlt 
molar not coming up until he is 
eif/hteen months old. 
From about ten months, a close 
inspection shows that changes are 
being wrought in the incisor teeth. 
Some of them have pretty well 
served their purpose. The jaws 
of the animal have grown wider, 
and room is thereljy made for the 
permanent teeth to come up. The 
fangs of the central pair are be- 
ginning to be absorbed from the 
Fig. 30. Lower jaw of a lamb nine months old, showing the fifth molar cut- 
ting. 4 and 5 are permanent molars ; 1, 2, 3, temporary. 
