A fine British author-illustrator blends several of his hallmarks in an effective plea for the environment. Sent brusquely to bed, a boy imagines a journey on his toy train, acquiring along the way a series of threatened animals who plead to be included (the seal says, ". . .people are making the water very dirty and they are catching too many fish, and soon there will be none of us left"). Meanwhile, the growing crew has fun--picnicking, playing ghosts, swimming, flying kites--each activity linked to the animals' plight. A neat surprise provides a chuckle at the end; mixed-media illustrations have Burningham's usual inimitable wit, beauty, and splendor.