[Perhaps from the apostle Peter's walking on the sea.] A genus of sea-birds allied to the gulls. The best-known spe-cies is the stormy petrel, well known to seamen as Mother Carey's chicken. The appearance o f these birds i s considered t o presage a storm, and they are often seen dur-i n g storms a t sea skimming over the surface of the water as if walking on it. Their food consists of small marine animals and seeds of sea-weeds, and they appear fond of fat or grease, for which they will follow in the wake of ships for great distances.