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POPULAR SCIENCE REVIEW. 
Guinea. (4) The rat-kangaroos ( Hypsiprymnus ), which have 
the first upper grinding tooth large, compressed, and with 
vertical grooves. 
Fig. 4. 
Skull of a Eat-kangaroo ( Hypsiprymnus ). 
These four genera together constitute the kangaroo’s family, 
the Macropodidce , the species of which all inhabit Australia 
and the islands adjacent, but are found nowhere else in the 
world. 
The species agree in having — 
(1) The second and third toes slender and united in a 
common fold of skin. 
(2) The hind limbs longer than the fore limbs. 
( 3) No inner metatarsal bone. 
(4) All the toes of each fore foot provided with claws. 
(5) Total number of incisors only -J. 
These five characters are common to the group, and do not 
coexist in any other animals. They form, therefore, the dis- 
tinguishing characters of the kangaroo’s family. This family, 
Macropod dee , is one of six other families which, together with 
it, make up that much larger group, the kangaroo’s order. As 
was just said, to understand what a kangaroo is, we must know 
“ what are the relations borne by its family to the other fami- 
lies of its order and accordingly it is needful for our purpose 
to take at least a cursory view of those other families. 
There is a small animal, called a bandicoot , which, in ex- 
ternal appearance, differs very plainly from the kangaroo, but 
resembles it in having the hind limbs longer than the fore 
limbs, and also in the form of its hind feet, which present 
a kangaroo structure, but not carried out to such an extreme 
degree as in the kangaroo, and therefore approximating more to 
the normal type of foot, there being a rudimentary inner toe 
and a less preponderant fourth toe ; the second and third toes, 
however, are still very small, and bound together by skin down 
to the nails. In the fore foot, on the contrary, there is a 
deficiency, the outer toes being nailless or wanting. The 
cutting teeth are more numerous, these being I 
This little creature is an example of others, forming the 
family Peramelidce — a family made up of creatures none of 
