Toby -- a real American mutt -- is as timid as Crockett Johnson's other Mr. Mittyish character, Harold. Toby first intimidates such terrible, terrifying phenomena as a squirrel, a frog and a bird. Then when a milk truck leaves after his barking at it, Toby hides under the bed, overcome with pride and fatigue. There he sees his own reflection in a mirror, is startled and frightened and finally realizes to his own amazement that he is terrible and terrifying. Children will like and laugh at terrible, terrifying, timid Toby. This has all the virtues of the comic book, but none of the faults. It's a funny little tale told mostly in pictures with none of the usual weaknesses of comic books, horror, violence or gore. On the contrary, this minimizes fears -- a healthy concept for children who know what fear is but don't know how to cope with it.