In the glare of noon-day this aerial athlete may perhaps be found in a
deep slumber, hanging head downwards behind the shutters of a cottage
window, or in some crevice of a barn-roof. Gently seize him and as
gently stretch out his wing. The moment one opens it one sees that it
is constructed upon a totally different plan from that of a bird. In
the first place a thin membrane, or fold of skin is seen to take the
place of the series of quill-feathers found in the wing of the bird. In
the second it will be found that this membrane is stretched between
a series of long and very slender bony rods. These are excessively
attenuated fingers. And if the hinder border of the wing-membrane be
traced inwards it will be found to be attached to the hind limb. In
some species it will be found that this membrane passes backwards
beyond the leg to attach itself to the tail. Here, then, is a wing
as efficient for its purpose as that of a bird, but constructed on a
totally different plan.
Ages ago, before even the birds or the beasts had appeared on the
earth, the winged dragons, which the Men of Science call Pterodactyles,
held the proud position of being, not only the first, but the only
creatures blessed with a backbone that could fly. Their wings
resembled those of the bats, but differed in this, that instead of the
wing-membrane being stretched between all the fingers, leaving only
the thumb free, it was attached only to the fifth finger, leaving the
remaining fingers free, and these were reduced to mere vestiges. As
with the birds, the breast-bone was very broad and was furnished with a
keel, while in the bats it takes the form of a jointed rod, down which
no more than a slight keel is ever developed.
But millions of years before the Flying-dragons, birds, and bats came
into being, the stupendous problem of flight had been solved. Far away
in the distant Devonian Epoch, when the distribution of land and water
over the earth's surface was totally different from that of to-day,
dragon-flies and caddis-flies disported themselves in the summer sun,
amid landscapes that would seem strange to our eyes. For there were no
trees and flowering plants, such as we know.
* * * * *
Public-domain text, read in full here on John Shaqi.
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