IN HERBIVOROUS ANIMALS. 
211 
3. At their external face, the molar teeth of the upper jaw pre- 
sent perpendicular canulrn, in number from two to three, according 
to which of these is examined. These canulee are separated, the 
one from the other, by salient columns, of which the free extremity 
at the side of the dental table is susceptible of forming asperities, 
very angular when they have not been used or worn by a regular 
grinding. 
The molars of the inferior jaw are not canulated ; they present 
only a ridge, often little marked, and which is situated principally 
on their inner surface. 
4. The molars of the superior maxilla form, in their succession, 
a range larger and longer than those of the inferior maxilla. This 
disposition, which results from the greater volume of the former, 
gives the key to the discovery of the causes of certain malforma- 
tions, as we shall hereafter expose in treating of dental pathology. 
5. When the dental arcades are examined in the head of a 
young horse, it will be seen that they differ, not only the one from 
the other by the volume of the teeth which constitute them, but 
also by their respective breadth. The ranges or rows of the supe- 
rior arcade are more distant each from the other than those of the 
inferior arcade, and they form two curves, of which the convexi- 
ties are externally situated. At the inferior arcade the molars 
are disposed in two lines, almost straight, converging towards each 
other at the region of the symphysis of the chin. 
6. The dental tables of the inferior arcade are disposed accord- 
ing to an oblique plane, whose descending direction is from above 
and within to below and without. The tables of the superior max- 
illa present an inverse disposition ; their plane is oblique from 
below and without to above and within. 
7. In a jaw which has been regularly used or ground, the dental 
tables in the two arcades present asperities and anfractuosities 
little marked, which receive each other reciprocally in such a 
manner, that in their approach and contact the relations of their 
surfaces is perfectly exact. 
8. From the disposition of the inversely inclined planes of the 
dental tables, and from the difference in the breadth of the arcades, 
it results that the relation cannot establish itself at both sides at 
the same time, between the teeth of the superior jaw and those of 
the inferior. It is only alternately that the rubbing and trituration 
can be executed from the one side to the other by a lateral move- 
ment of the lower jaw upon the superior. 
9. In herbivorous animals, more particularly the horse, and other 
monodactyles whose food is of such a nature as to require an 
enormous degree of mastication in order to render it fit to be acted 
upon by the gastric j uice, bile, &c., the teeth have the property of 
