. . . And the smile was on the croc-o-dile!"" Very likely the lady was inside him if she got close enough to ""see whether the fourth tooth on the lower jaw is out or in when the jaws are closed,"" the method suggested by Mr. Ricciuti as the ""easiest"" way to distinguish the alligator from the crocodile. Perhaps he assumed that both reptiles would have to be present for the American Heritage dictionary distinction (the alligator has the ""broader, shorter snout"") to be applied. As for the American alligator's life cycle and behavior patterns, it seems that scientists do not yet have a complete picture. We do learn however of the four quite different habitats typifying the ""'gator country"" of the Southeast and of the alligator's role in the balance of life around the water hole. Though responsible for the deaths of some of the birds, turtles, and other animals, his presence insures the survival of many more. Ricciuti's descriptions of ""puffy white clouds"" sailing in deep blue skies over not-quite-poetic catalogs of indigenous plants and animals sometimes obscures hints of intricate ecological interdependencies, but his concern about the disastrous consequences of man's interference is dear. Acknowledging that conservationist efforts of the late '60's have done much to reverse the trend toward the alligator's extinction, he suggests alligator farms as a possible solution of the future.