The wings of all differ conspicuously from those of other birds 
in the great length and looseness of the texture of the feathers. 
Those of the African ostrich are the largest of all; but they are 
quite useless for the purpose of flight, though they are used as 
aids inrunning. In the South American ostrich, or rhea, they are 
also large, but again useless for flight, for the “ quill-feathers ” 
are very weak, and have no “ web,” such as one finds in the quills 
of flying birds. And besides, the muscles of the wing have 
degenerated, the breast-muscles having become reduced to 
mere vestiges. 
In both the African and South American ostriches, the 
skeleton of the wing, compared with, that, say, of a swan, would 
seem, to the inexpert, to be quite normal. But with the cassowary, 
the emu, or the apteryx matters are very different. Here, at the 
first glance, it is apparent that the process of decay is far advanced ; 
for the bones of the hand have, as it were, shrunk up, so that 
a mere stump is all that remains. The wing of the cassowary is 
further remarkable for the fact that some of the fore-arm quills, 
or ‘‘ secondaries ”’ are represented by long, stiff quills, resembling 
spines of a porcupine ; the “ vane ” of the feather, which normally 
runs down each side of the shaft, has vanished altogether. What 
part they play in the bird’s life history it is impossible to say. 
They certainly cannot be used as weapons, and they as certainly 
“ce 
are not “ornaments.” In the extinct moas the wing had still 
129 
