588 
MANUAL OF MODERN FARRIERY. 
also termed the incisors, but is furnished with eight cutting- 
teeth in the lower jaw. 
At two years of age two of these drop out, and arc 
replaced by other two. At three years old four of them are 
renewed, and the others at the age of four years. 
The teeth undergo considerable changes between the first 
and eighth years, which we have delineated in plate xiii., so 
as to enable persons to judge of the age of sheep by their 
dentition. 
Fig. 5 exhibits the appearance of the teeth at one year 
old. Their cutting, or outer edges form a crescent-shaped 
line, the teeth being nearly all of a similar breadth, almost 
flat, and very smooth on their outer surface, and consider¬ 
ably concave internally. 
Fig. 6 shows their aspect at two years of age, in which 
the two central teeth are considerably broader than the 
others, with the cutting edge not nearly so much arcuated 
as at two years. 
Fig. 7 represents the structure of the teeth at three years, 
from which it will be observed that the four central ones 
are considerably broader and longer than the other two on 
each side, which rather suddenly shorten, the external teeth 
being shortest and narrowest: the cutting edge of the four 
central ones is but slightly curved. 
Fig. 8 characterises the teeth at four years, and shows 
that the six central ones are nearly of uniform breadth and 
length; their cutting edge being but very slightly curved, 
the external tooth on each side being materially shorter 
than the others. The whole of the teeth are much stronger 
than in any of the preceding years. 
Fig. 9 shows the structure of the teeth on the fifth year. 
It will be observed that the whole eight teeth are nearly 
straight on their cutting margin, and that there is but a 
