Zim's factual reports on various creatures are consistently successful. This time he has chosen ostriches, the oldest and simplest of bird life extant. They neither fly nor- despite legend- bury their heads in sand. The ostrich egg is the equivalent of about two dozen hen's eggs, but as a source of food they are scarcely comparable. Simple, direct illustrations and diagrams demonstrate the connection of the keel-shaped breast- bone of most birds -- the raft-shaped breastbone of the ostrich- with the ability to fly. Dr. Zim relates this ancient species to natural history and to social history. In ancient Rome their meat was considered a delicacy; in recent decades, their plumage was fashion's favorite. This is a compendium of facts so sleekly fashioned as to be painless. Questions are answered; others are raised. A stimulating job.