wrist-bones may be found. And the “ palm-bones,’”’ which 
in the adult are welded together, are here quite separate. 
This stage, then, carries us back towards the ancestral, 
reptilian fore-limb used for walking, or perhaps for climbing. 
And there is another sign of this earlier reptilian period to be 
found in such a wing. At the tip of the thumb and first 
finger in unhatched ducks, game-birds, and water-hens, for 
example, you will find a small claw. By hatching time the 
claw of the first finger will have disappeared, but it is still 
retained in the case of the duck and the water-hen. In the 
adults of all three you will rarely find more than the claw of 
the thumb: and this now serves no useful purpose whatever. 
Indeed, there seem to be only two tribes which have any 
use for wing-claws during nestling life. One of these is 
represented by the gallinules, that is to say, the coots, and 
water-hens, and their kind. You may test this whenever you 
have the good fortune to capture a young water-hen. Place 
him outside the nest, and especially if it happens to be a 
little raised, you will see him make his way back, using feet, 
wing-claws, and beak. His wings, it will be noticed, at this 
stage are used as fore-legs. The other tribe is represented 
by that strange bird the hoatzin of the Amazon. Here the 
two claws are really large, and they play a quite important 
part in his early life. 
For the young hoatzin is hatched in a nursery—a crude 
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