We ourselves, as well as the animals about us, have two pairs of limbs. So has the bird; it is built on the very same plan, except that it has wings instead of arms or forelegs.
"Teacher made us compare our own arm and hand with the wing of the bird. We have an upper arm, a forearm, and a hand. The bird has all these parts to its limb, but the bones are lengthened to make a wing for flying.""Do you know which part of our lesson pleased me most, Fred?""I suppose you are thinking about
the mouths and feet of the birds," said Fred.
"Yes, I am," replied Will, "for I can"t help thinking that it is very wonderful.
"You know, Norah, we learned a long while ago to look into the mouths of animals when we wanted to find out all about them, their food and their habits. The teeth of the animal tell us all we want to know.
"Teacher showed us a great many heads of birds. They all have hard horny beaks or bills instead of mouths, but the bills are not all the same shape.
"The bill forms mouth and teeth all in one, for birds have no real teeth. We call the two parts of the bills the mandibles.
"Teacher says the bills are not all alike, because the birds themselves are not alike in their nature, their habits, or their food.
