KANGAROOS. 
239 
SKULL OF LESUEUR’S RAT-KANGAROO, 
c, tusk, or canine tooth. 
and adapted for cutting. As a rule their upper canine teeth, or tusks, are small, 
or wanting; and this invariably holds good for those of the lower jaw. As 
regards their molar teeth, these are invariably characterised by having broad, 
flattened crowns, surmounted either by tubercles or transverse ridges, and adapted 
for the trituration of vegetable substances. 
The members of the kangaroo family vary greatly in size, and in the relative 
length of the hind-limbs, but they are collectively characterised as follows. In the 
upper jaw there are three pairs of incisor teeth, with sharp and cutting edges; 
while the lower jaw is furnished with a large single pair inclining forwards, and 
sometimes biting against one another 
with a scissor-like action. The upper 
canine, or tusk, if present at all, is of 
small size, as in the accompanying 
figure; while there is no corresponding- 
lower tooth. In the adult the cheek¬ 
teeth are five in number on each side, 
of which the first is a premolar; this 
condition obtaining in the figured skull. 
In young animals there are, however, 
two milk - molars in place of this 
premolar; the number of cheek-teeth 
then being six on each side. The molar teeth themselves may carry either a 
pair of transverse ridges, or four blunt tubercles. A characteristic feature of 
the family is to be found in the lower jaw, which has a deep pocket in the outer 
side of the hinder portion, communicating at its base by a large perforation with 
the canal on the inner side. The pocket is shown in the accompanying figure, 
but the communicating aperture is concealed by its outer wall. In all the 
members of the family the fore-limbs are short and feebly developed, with five 
complete digits. The hind-limbs, on the contrary, are very powerful, and more 
or less elongated. Usually they have but four toes, of which the one corre¬ 
sponding to the fourth in the typical series of five is much larger than either of 
the others, and terminates in a huge claw. The outermost toe is considerably 
smaller, but still stout. The two toes on the inner side of the large one, corre¬ 
sponding to the second and third of the typical series, are, however, reduced to 
small slender rods, lying parallel to one another, and enclosed in a common 
skin. These rudimental digits are of course useless in progression, and their 
aborted condition is technically known as syndactylism. The head, especially 
in the larger forms, is small in proportion to the body, and tapers towards the 
muzzle. Generally the tail is long, cylindrical, and tapering; while it frequently 
aids in supporting the body, and may be prehensile. The female is provided with 
a large pouch, of which the aperture looks forwards. 
All the members of the kangaroo family are purely vegetable feeders, and are 
mainly confined to Australia and Tasmania, where, before the introduction of 
sheep and cattle, they took the place of the ruminants of other regions. They are 
divided into numerous genera, of which the first includes the true kangaroos 
and wallabies. 
