358 On the Teeth of the Ox, Sheep, and Pig, 
important change also marks the completion of the year, namely, 
the shedding of the deciduous and their replacement by the per- 
manent molars. The two anterior teeth are generally the first 
to fall, and are presently followed by the third. 
By the time the animal is fifteen months old these permanent 
molars will have acquired nearly, if not quite, the level of the 
others. Fig. 53 gives a side-view of the lower jaw at this age. 
The teeth I am now describing give evidence, fiom the sharpness 
of their points, of having been recently cut. They stand in front 
of the other molars, and are indicated by the numerals 1, 2, 3. 
The other changes effected between twelve and fifteen months 
relate chielly to the growth of the teeth. The permanent inci- 
sors, occupying the front of the lower jaw, have now attained 
their full length. The tushes are grown to a still greater extent, 
and are taking, as segments of a circle, a gentle sweep upwards 
and backwards. The corner teeth are likewise large, and the 
lateral temporary incisors still in situ. 
At eighteen months, or thereabouts, the dentition of the. pig 
may be said to be completed by the cutting of the lateral incisors 
and of the last or sixth molar. Fig. 54 represents, as before, the 
front of the lower jaw. The teeth just cut are marked l. i. It 
Fis. 54.* 
* Fig. 54. Front view of the lower jaw at 18 months, l. i.. the lateral, /le;- 
manent. incisors are represented as being recently cut and not yet ou a level with 
the middle pair. 
