as indicative of the Age of the Animal. 
319 
named, as these teeth likewise furnish important evidence of 
age during the early period of the animal's life. At birth 
none of the molars have cut the gum, and it is not until the 
calf is a month old that they are well developed. Like the 
incisors, they follow no special order of eruption, but more fre- 
quently than otherwise the first in position is the last to be cut. 
The first and second of the temporary molars in either jaw 
do not differ essentially in form from the permanent, by which 
they are succeeded. If we compare, however, the teeth of the 
upper jaw with those belonging to the lower, it will be found 
that the two anterior molars in the lower jaw are much smaller 
than the corresponding ones of the upper, still these points are 
of less practical import than others which have to be named. 
The tkird in position of the temporary molars in the lower jaw 
varies considerably from all the others, as also from its permanent 
successor. It differs likewise as greatly from the fourth in situa- 
tion, the first permanent which is put up, and with which it can 
scarcely be confounded even in a casual examination, if the fol- 
lowing particulars are borne in mind. It is the last of all the 
temporary molars which, as a rule, is renewed, and consequently 
throughout it furnishes much assistance in determining a Cj[ues- 
tion of age. Figures 22 and 23 show it occupying a space in the 
jaw equal to or even greater than both other molars together 
which stand before it^ in consequence of its increased width 
from front to back, more correctly called its long diameter. It 
is composed of three main parts or lobes of a semi-cylin- 
drical form, having in the hollows between them, on the outer 
side, two smaller portions which also rise into asperities or 
cusps. The latter, when the tooth is somewhat worn down, add 
both to the strength of its body and the irregularity of its 
grinding surface. 
Each of the three principal lobes likewise rises into cusps, 
an inner and an outer, of which the inner are always the highest. 
In fig. 17, a representation of this molar, as removed from the 
jaw, is inserted. The description there given shows how the 
roughness of the face of the tooth is added to by the wearing 
away of the cusps. This tooth being of triple form, might, for 
brevity's sake, be called a tri-cuspid tooth ; but this, critically 
speaking, is far from being correct, for originally, as Ave have 
seen, it has six principal with two minor projections or cusps. 
These particulars suffice to distinguish the third temporary 
molar so well, that in examinations of the mouth it is quickly 
recognized. By merely bearing in mind that this tooth has three 
lobes, while both the fourth and the fifth molars have but two, 
and that when it falls it is replaced by a tooth similar in size and 
form to them, we recognize immediately both the number and the 
Y 2 
