The Big Pets

``The girl was small and the cat was big,'' begins a bizarre nighttime journey during which small children and their giant pets frolic somewhere in the dreamy heavens. The girl and her oversize cat are joined at the Milk-Pool by other happy felines, who lap milk as the children swim. Dog fanciers flock to the Bone Gardens, where friends and pets dig for fossils; Hamster Holes are the favorite haunt of hamsters and their owners, who take turns popping in and out of the ground. Told in a simple, straightforward style, this fantastic story is enhanced with dark, jewel-like paintings that exhibit an almost phosphorescent glow. Smith's ( The True Story of the Three Little Pigs ) sophisticated illustrative technique has mellowed handsomely. His use of collage has been minimized, and his attention to content and dimension have resulted in enticing illustrations that provide the perfect landscape for this nocturnal romp. Ages 3-8. (Mar.)