Feet and Legs 393 
distance without having to cross level or open ground; 
. . at the slightest alarm they either drop into a crevice 
or bound from rock to rock with extraordinary speed, look- 
ing more like india-rubber balls than birds, for there is no 
perceptible interval between the end of one leap and the 
beginning of the next, and the distance they can clear at a 
single hop must be seen to be believed. Should they have 
to cross a piece of level ground between two rocks which 
they cannot clear with asingle bound, they run across it with 
great speed and usually with outspread wings. So feeble 
are their powers of flight that they seldom attempt to 
fly, and never when in a hurry or alarmed; at the most 
they flutter feebly for a few hundred yards down hill. 
' I have occasionally amused myself by trying to drive 
these birds across a piece of open ground, but I have never 
succeeded in getting them to quit the shelter of the rocks, 
where they easily avoid one by leaping over the stones 
or hiding in the crevices. In spite of his loose, fluffy 
plumage, which blows about in the slightest breeze and 
gives him a rather untidy appearance, the cock is an ex- 
ceedingly handsome bird.” So we have here an isolated 
case of direct relation between two organs, the balance 
of power changing from wing to feet and affecting much 
of the bird’s structure, even the plumage losing its cohe- 
siveness. The weak-flying Tinamou have unusually sturdy 
legs, and many other instances might be mentioned. 
For many reasons the most interesting of all birds’ 
feet are those of the ostriches and their allies, and among 
them the most extreme examples of this same cause and 
effect are to be found. 
