grinders in both jaws, as the age of the animal ad- 
vances. They have some resemblance in form to a 
cone; they protrude about an inch from the gum, 
and have a curved and sharp-pointed extremity ; 
they belong far less to the mare than to the male 
horse, being only stumps or germs in the former 
at five years of age, though fully developed in the 
latter ; and they perform no apparent office in 
mastication, but seem to have served, in the wild 
condition of the horse, as his principal weapons 
of offence. The yrinders—also called molars, jaw- 
teeth, or back teeth—are twenty-four in number, 
twelve above and twelve below ; they are strong 
double teeth, with sharp edges, but gradually lose 
their sharpness and become smooth as the animal 
advances in age; and they have great strength 
and endurance, and are employed in grinding 
down the hardest portions of the horse’s food. 
|. Enamel, similar to that of the nippers, completely 
| covers the tops and sides of the grinders ; but 
| this is gradually worn from the tops by the mutual 
' attrition of teeth and food ; and what remains is 
a compound surface of alternate layers of crusted 
petraser, enamel, andivory. Hach grinder of the 
upper jaw axoractices§ in embryo of five bony sub- 
stances or teethlets agglutinated by a powerful 
| cement into one compound tooth; and each 
| grinder of the lower jaw consisted in embryo of 
| four teethlets, and is smaller, narrower, and more 
| regular than an upper grinder ; and both, in con- 
sequence of their complex formation and mutual 
adjustment, possess a power of trituration, a 
strength of resistance, and an adaptation to the 
peculiar wants and constitution of the horse, 
which, in common with all the innumerable in- 
tricacies of animal organism, strikingly indicate 
the wisdom of the Creator. Neither the upper 
nor the lower grinders are placed horizontally ; 
but the upper have their higher side without, 
and shelve inward; the lower have their higher 
side within, and shelve outward,—and thus they 
achieve the grinding motion with a facility of 
action and a maximum of power, which indicate 
the beneficence and skill of the Almighty Maker. 
The highest criteria of age are afforded by the 
nippers ; the next highest, by the grinders ; and 
the least, by the tushes. 
At the time of the foal’s birth, or within three 
or four days after it, the first and second grinders 
of both jaws protrude through the gums, and are 
very large in proportion to the size of the jaw. 
About seven or eight days after birth, the two 
central nippers will be seen, as represented in fg. 
1, Plate J,; and though they afterwards seem small 
in comparison with the permanent teeth of the se- 
cond set, they at present appear so large as to fill 
the front of the mouth, Before the end of four 
weeks, the third grinder protrudes both above 
and below ; and before the end of six weeks, 
two nippers, additional to the two first, and at 
the sides of them, will protrude both above and 
that he has only four nippers, two in each jaw, 
below, so that if you, on raising a colt’s lips, find 
AGE OF ANIMALS. 
59 
you will know that he is a week old; but if, in- 
stead of four, he perceives eight, as in /%g. 2, 
Plate I., you may know he has been dropped at 
least a month. At the end of two months after 
birth, the two first nippers will have attained 
their full height ; and before the end of the 
third month, the second pair will be on a level 
with the first. From the third month till between 
the sixth and the ninth, both pairs of nippers will 
begin to be a little worn, and their outer edge, 
which was originally somewhat sharp and raised, 
will be reduced to a level with their inner edge. 
Between the sixth month and the ninth month, 
a third pair of nippers will protrude from above, 
and also a third pair from below ; thus completing 
the colt’s set of incisors, asin /%g.3, Plate. From 
this time till between the second and the third year, 
the several pairs of nippers will undergo change, 
and indicate age; only in their gradual wear. 
The foal’s nippers—altogether twelve in number, 
and technically called milk-teeth or foal-teeth— 
are easily distinguished by their smallness and 
whiteness from the permanent ones which succeed 
them ; they bear considerable resemblance to the 
foreteeth of a man; they are rounded in front, 
and somewhat hollow behind; and, previous to 
their being worn to a level by use, they possess 
a cutting surface, with the outer edge rising 
slantingly above the inner edge. 
of nippers are nearly level on the surface, and 
the third pair have lost some of their slant and 
sharpness; and ‘the mark’ in the first pair is 
wide and faint ; in the second pair, darker, longer, 
and narrower than in the first ; and in the third 
pair, darker, longer, and narrower than in the 
second. Hither at the completion of the first 
year, or soon afterwards, the animal gets a fourth 
grinder, so as to have six nippers and four grinders 
above, and the same number below; and from 
these indications—liable, however, to a little va- 
riation from differences in the time of weaning, 
and in the nature of the food subsequently used 
—its age may be accurately known. At the age 
of eighteen months, all the nippers are worn flat ; 
and the mark in the central pair is much shorter 
and fainter than at twelve months, while that in 
the other pairs is also much changed; and at 
the age of two years, the indications in the mark 
of the nippers are increased, the fifth grinder 
protrudes both above and below, and the front or 
first grinder gives way, and is succeeded by a 
large and permanent tooth, the first of the set or | 
series belonging to the adult horse. | 
The teeth of the second or permanent set begin 
to be secreted even at the foal’s birth ; they slowly 
and gradually grow beneath the roots of the first, 
pressing upon them, and causing them to be taken 
progressively away by the absorbent vessels ; and 
in general they continue this process till the 
crowns of the milk-teeth are quite deprived of 
their roots, and drop out; but in a few instances 
they push so far by the side of the milk-teeth, 
When the ani- | 
mal is a year old, the first and the second pairs _ | 
