360 
On the Teeth of the Ox, Sheep, and Pig, 
but they cannot mislead if clue attention be given, being so self- 
apparent as easily to be detected. 
Fig. 55 relates to the eighteen-months-old pig. It gives a 
representation of the sixth or last molar, and shows also the 
condition of all the teeth of tlie lower jaw when dentition is 
perfected. The sixth molar tooth greatly exceeds the others in 
size, and cannot be mistaken for any of them. It is composed of 
three principal parts blended together as in the third temporary 
molar of the lower jaw. Each portion rises separately to form 
two principal cusps, which in the cutting tooth are beautifully 
intersected with depressions of various depths, forming altogether 
a minute rockwork, as it were, of enamel. This condition, 
however, of the crown after it has penetrated the gum and been 
brought into use is soon effaced by daily attrition. Its superior 
size is nevertheless its distinguishing and permanent feature. 
Fig. 3 shows the cap of enamel which crowns this tooth just 
prior to its protrusion from its socket. In fig. 55, also, some of 
the molars will be observed to give evidence already of wear, 
particularly the fourth and fifth, arising from their having come 
early into use. Tiie first named of these teeth, it will be remem- 
bered, was cut when the animal was six months old, the second 
when about nine. 
Between one year and a half, and a year and three quarters, the 
permanent incisor teeth reach their fullest development ; after 
this period their length, in the lower jaw particularly, begins to 
lessen. We are only enabled to judge the age of the female 
after this time by the wear the teeth as a whole have undergone, 
and her general appearance. In the perfect male, however, the 
tushes will not as yet have acquired their greatest size, and will 
therefore afford us some further assistance. The length to which 
they will grow, and the elegant sweep in an upward and backward 
direction which the lower one takes, and the outward and 
backward course of the upper, are correctly represented in fig. 56, 
a sketch taken from a specimen forwarded by Mr. Robinson, V.S., 
of Tamworth, to whose kindness I am likewise indebted for others 
which have materially assisted my investigations. With regard, 
however, to this full development of the tushes, it must not be 
forgotten tliat their position being subject to slight variation, 
will likewise influence the amount of their wear, and consequently 
give them a somewhat stunted appearance, earlier in some ani- 
mals than in others. Some boars too are addicted to champing, 
which action of the jaws when the tushes are so placed as to rub 
each other will quickly reduce both the length and size of these 
teeth. 
I will now, as with the ox and sheep, attempt to embody, in a 
tabular form, the chief facts of the dentition of the pig. The 
