374 
POPULAE SCIENCE EEYIEW. 
and there is no representative of our great toe — not even that 
part of it which is enclosed in the substance of our foot, called 
the inner metatarsal bone . Two other points are specially 
noteworthy in the skeleton. The first of these is that the pelvis 
(or bony girdle to which the hind limbs are articulated, and 
by which they are connected with the back-bone) has two elon- 
gated bones extending upwards from its superior margin in 
front (fig. 1 a). These are called marsupial bones, and lie with- 
in the flesh of the front of the animal’s belly. The other point 
is that the lower, hinder portion of each side of the lower jaw 
(which portion is technically called the 44 angle ”), is bent in- 
wards, or 44 inflected,” and not continued directly backwards in 
the same plane as the rest of the lower jaw. 
A certain muscle, called the cremaster muscle, is attached to 
each marsupial bone, and thence stretches itself over the inner 
or deep surface of the adjacent mammary gland or 44 breast,” 
which is situated low down, and not in the breast at all. 
The kangaroo’s teeth consist of three on each side in the 
front of the mouth, and one on each side below. These eight 
teeth are what are called incisors. At the back of the mouth 
there are five grinding 
teeth on each side above 
and five below, and be- 
tween the upper grinders 
and incisors another point- 
ed tooth, called a canine, 
may or may not be inter- 
posed. Such a set of 
teeth is indicated by the 
following formula, where I stands for incisors, C for canines, 
and M for grinding-teeth or 44 molars.” The number above 
each line indicates the teeth of each denomination which exist 
on one side of the upper jaw, and the lower number those of the 
lower jaw : — 
Fig. 2. 
Teeth of Kangaroo {Macropus). 
9 
6 
or 
8 
6 . 
The total number of incisor teeth of both sides of each jaw 
may therefore be expressed thus: I |. 
Such is the general structure of an adult kangaroo. At birth 
it is strangely different from what it ultimately becomes. 
It is customary to speak of the human infant as exception- 
ally helpless at birth and after it, but it is at once capable of 
vigorous sucking, and very early learns to seek the nipple. 
The great kangaroo, standing some six feet high, is at birth 
scarcely more than an inch long, with delicate naked skin, and 
looking like part of an earthworm. Born in such feeble and 
imperfectly developed condition, the young kangaroo cannot 
