OTHER KANGAROOS 
and the jerboa-rats of Australia, and by the Cape 
jumping hare (Pedetes caffer) of Africa. To be agile, 
to traverse arid wastes in the search for water or for 
herbage, with rapidity, is a sine quad non with all these 
creatures which have a partiality for plains, and arid 
ones at that. It is interesting and most instructive 
to note how differently in such cases the feet have been 
constructed for the due carrying of their owners over 
the ground. In the ungulates either the middle toe 
or the third and fourth has or have been especially 
strengthened to meet the demand. In the jerboa 
the Perissodactyle type of foot has been, we must 
suppose, quite independently acquired; for in them 
digit number three is in the middle and strikes the 
ground first. In the kangaroos, on the other hand, it 
is the fourth toe which is predominant; and it is, as 
may be easily seen in the living animal, particularly 
strong and furnished with a huge nail. In bipedal 
man it is the innermost toe, the first, which mainly 
bears the weight of the body. There is thus nearly 
every possible arrangement, which varies according 
to the group. In the kangaroo the peculiarly tiny 
third and fourth toes will be noticed to be tied up in a 
common integument. How thick blood is among the 
marsupials is shown by the fact that in the phalangers, 
arboreal creatures quite unlike the kangaroos in general 
aspect, the same toes are similarly swathed in skin. 
There are between twenty and thirty kinds of kan- 
garoos, including the so called wallabies which are not 
now distinguished from the kangaroos ; the only differ- 
ence that ever existed was merely one of size. 
THE TREE KANGAROO 
The idea of a kangaroo up a tree suggests a purely 
metaphorical use of the term to most persons for whom 
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