Nancy Barko, Age 10, F East Brunswick, N.J., for her question:

Did snakes, ever have legs?

All the snakes are descended from lizard ancestors. In the remote past, these snaky ancestors crbwled around on four feet, just as the lizards do to this day. Then their legs began to wither away. Perhaps the front legs disappeared first, but after countless generations, the snakes also lost their back legs.

This development took a long time, and certain snakes still show evidence that their ancestors once had legs. Their skeletons reveal small useless bones just where the bones of their back legs would have been. These bones, we are told, are all that remain of the hip and leg bones which their ancestors once had.