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India and its islands, living in forests and making its way among 
the trees, by the help of its long arms and lengthened feet, most 
rapidly :—swinging, leaping, and throwing itself from tree to tree, 
it sets pursuit at defiance. Now why these long arms confined 
to this particular species? Almost the whole of the monkey 
tribe are more or less sylvicole (dwellers in woods), and long arms 
would be as much an advantage to one species as another. We 
ean’t explain this. We can only say that gibbons must have 
enjoyed this advantage over a very long period of time for the 
arms to have attained to this growth. They are found in a fossil 
state in the S. of France, and it would be of interest to know if the 
arms of any fossil species were as long as those of the living. 
But this need not necessarily be, for there are some other living 
species which have not got arms of the same length as the 
Hylobates agilis. 
And while on the subject of monkeys, let us consider the case 
of the prehensile-tailed monkeys of America. There are several 
marked characters of distinction between the monkeys of the Old 
world and those of the New—(though they must surely all have 
been derived from one and the same primitive stock originally)— 
but I will only dwell on the character of their tails. In a large 
proportion of the American monkeys—not in all—the tails 
are not only long, but their under surface, at the extremity, 
is denuded of hairs, and covered with a sensitive skin, rendering 
it as delicate a tactile organ as a man’s fingers. With this tail 
they can grasp the bough of a tree, as a man would with his 
hand. Securely holding on, they can swing by it, or gradually 
increase the extent of the swing till able to grasp a more distant 
branch with their hands, and so travel on through the woods 
wherever they would go—with fearlessness and the most 
marvellous celerity. : 
. Now why is this advantage confined to the New world monkeys? 
The Old world monkeys, who also live in woods, no doubt, did 
they possess it, would gladly avail themselves of such a help in 
