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 a single 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. 



