A round hound (a greyhound, curled up in a circle) and a round hog (or groundhog, for which roundness comes naturally, no effort or repose required) are at the center of a picture book following them from initial meeting (once the greyhound awakens) through their dizzying, delightful encounter. “A round hound, a grey dog, a round little hound dog. A grey hog, a ground dog, a hog little hound dog.” The story unfolds in a mirthful, rhyming text comprising a limited number of words rearranged, and occasionally expanded (how many words rhyme with “round”?). The synergy between Emily Jenkins’s words and illustrator Chris Appelhans’s illustrations is superb. In the art, a muted palette on creamy white pages, grey (hound) and brown (groundhog) predominate in compositions that echo and extend the duo’s playful, sometimes frenzied interaction. There are also soft punctuations of other colors, as when butterflies appear and “astound and astound!” the two creatures. It’s waggish, waddling, tongue-twisting fun, perfect for playful, sound-rich reading aloud. (Jenkins offers a “debt of inspiration and rhythm” to Ruth Krauss’s A Very Special House.) (Ages 3-7)