280 
On the Teeth of the Ox, Sheep, and Pig, 
dered evident when the succession of the first and second sets of 
the teeth of the ox, &c., is explained. 
I now pass on to make some general remarks upon the three 
kinds of teeth of the Mammalian class, namely — incisors, tushes, 
and molars. 
The names given by anatomists to the teeth are determined 
more by their situation and function than by tlieir size or form. 
These names are therefore equally applicable to the first or 
deciduous, as to the second or permanent set. Several of the 
illustrations given in these pages will show these different kinds 
of teeth and likewise their relative positions. We may select 
fig. 56, as an example. 
The teeth designated incisors are always placed in the front 
of the mouth, and their situation here admirably adapts them 
for seizing the food. In the domestic herbivora, as our most 
familiar examples of the great family of the graminivora, we see 
that each animal, more or less, employs the incisors to lay hold of 
the herbage and to separate it from the roots by a clipping mo- 
tion of the jaws. Tlie lips and tongue, as well as the teeth, are 
used for this })urpose, and consequently more or less are also 
organs of preliension. The horse, when grazing, grasps the 
herbage Avith the lips, and thus conducts it between the incisors, 
which he now employs for the purpose of both holding and 
detaching it from the roots — the latter action being assisted 
by a peculiar twitch of the head. The sheep gathers his food 
in a similar manner. This animal is enabled however to bring 
his cutting-teeth much nearer to the roots of the plants in con- 
sequence of a partial cleavage of the upper lip. Hence the adage, 
that the " sheep will fatten where the ox will starve." The 
upper lip of the sheep, from its peculiar formation, is likewise 
endowed with considerable mobility, although to a far less extent 
than tliat of the horse. It is thin compared witli many other 
animals, and protected from injury to some extent by a covering 
of hair, existing everywhere except at the place of its cleavage. 
Like the ox, also, a large amount of fluid is poured from its 
glandular follicles which thickly beset the hairless parts ; and 
thus, by the moisture with which it is bedewed, it is further 
guarded from injury. 
The ox chiefly uses his tongue in the collection of his food. In 
him the upper lip is thick and hairless, and has a very limited 
action. Most ruminants possess a great freedom of movement of 
the tongue : this is well seen while the ox is grazing on luxuriant 
herbage. The organ, being protruded from the mouth, is so directed 
as to encircle a small bundle of grass, which it conducts between 
the incisor teeth and the dental pad. Here it is cut asunder by the 
.action of the incisor teeth, assisted, as in other animals, with a 
