"Poor little mousey!" said the Doctor, as he took the limp body from
the terrier's mouth. "It is quite dead. I am sorry, but it might have
nibbled some of my birds. Besides, this is exactly what I wanted to
teach you something about. Who can tell me the difference between a
mouse and a Sparrow?"

"I can!" said Dodo; "it's all difference; a mouse hasn't any feathers,
or any wings, and it has four feet, and a long tail and whiskers and
teeth--"

"That will do, little girl, for differences; do you see anything alike
between a Sparrow and a mouse, Rap?"

"I think the fur is something like feathers, Doctor," answered Rap; "and
you told us how a beak was like a mouth without any teeth or lips; then
a mouse has four feet and legs; but a bird has only two feet, and two
wings instead of four legs and feet like a mouse."

"That is just what I want you all to think about," said the Doctor. "Now
listen. If a Sparrow has a pair of feet that correspond to a mouse's
hind feet, what do you think a Sparrow's wings correspond to in a
mouse?"

"I should think they would be something like a mouse's fore feet,"
answered Rap, after thinking a moment.

"That is exactly right. Birds and beasts are alike in many respects.
They have heads, necks, and bodies; they have tails; and they have
limbs. Beasts have two pairs of limbs. We call them fore legs and hind
legs. People have two pairs also. We call them arms and legs. So you see