392 The Bird 
are doubtless of considerable use when the bird is emerg- 
ing from the water, which it generally does with a sudden 
spurt of speed and a strong leap which lands it on its feet. 
In landbirds which have either lost or are losing the 
power of flight there is often an interesting correlation 
to be observed between the lapsing of this mode of loco- 
Fig. 307.—Feet of Penguin. 
motion and an increased use and consequent greater de- 
velopment of the legs and feet. Of a South African bird, 
about the size of our American Robin, known as the Rock- 
jumper, it is said: “These curious birds are only to be 
found on the rock-strewn slopes and summits of mountain- 
ranges where they are able to hop from rock to rock for a 
