Judging from revent juvenile book lists dinosaurs have come back, but here that's just the dream of a kid who imagines a line of newspaper-reading commuters being carried to work on a docile giant's back. . . or a crested one replacing a lawnmower. . . a tall one serving as a ladder. . . triceratops plowing fields with his horns. . . allosaurs chopping down trees with their teeth. . . and so on. There are many more instances of dinosaurs' imagined usefulness, and on the last page Most gives the names for the 23 different ones he has pictured. The whole idea proves less than fertile as we move from one example to another, none of them especially witty, but other dinosaur enthusiasts might be induced to join the game with job assignments of their own. And no doubt there are earnest upbringers among us who will approve the tameness and productivity of these domesticated beasts.