Janet Strickland, age 13, of Portland, ore., For her question:

How do alligators and crocodiles differ?

You can recognize the crocodile at a glance. He is the fellow with the wicked¬ looking, toothy Smile. The alligator can close his big mouth and hide most of his toothy jaws. The crocodile cannot do this. The alligator has a wider snout, but at his best he is smaller than Mr. Croc, who may be the largest reptile in the world.

Both the alligator and the crocodile have a pair of extra long teeth in their lower jaws. The alligator has two pits in his upper ,jaw, and when he closes his mouth the long, lower teeth fit right into these pits, out of sight. The long, lower teeth of the crocodile fit into grooves on the outside of his upper Jaw. He cannot hide them, and when his mouth is closed they add that secret smile to his bumpy face.