Animals that go on all fours are called _quadrupeds_.

Animals that go on their two hind limbs only, like Bird People and House People, are called _bipeds_.

A Sparrow's wings are just as much like a mouse's fore legs, as a Sparrow's feathers are like a mouse's fur." "How funny!" said Dodo.

"But how are a bird's wings like fore legs, when they haven't got any paws or toes--or fingers--or claws--only just long feathers ?" "They have fingers, and some birds' wings have claws; only you cannot see them, because they are all wrapped up in the skin and covered over with the feathers.

Some day--not to-day, because you have had a long lesson already--I will show you a bird's wing with only its bones.