We wish to express our gratitude to Dr. Edmund S. Hobson of the Southwcst Fisheries Center-Tiburon Laboratory, National Marine Fisheries Service, NOAA, for critical reading of the manuscript. Thanks are also due to Mr. Jiro Nagano at the Keiyo Office and the staff at the Okinawa Branch of the Ocean Works of Asia, Inc., for enabling us to accomplish our field work so efficiently, and due to the Naha Regional, the Naha Coastal, and the Urasoe Fishermen's Unions, Okinawa Prefecture, for allowing access to reef areas under their jurisdiction. We are grateful to Dr. Kenji Mochizuki of the University Museum, University of Tokyo, for his valuable advice and encouragement, to Dr. Jack T. Moyer of the Tatsuo Tanaka Memorial Biological Station for advising us on our English, and to Mr. Jun Hashimoto of the Japan Marine Science and Technology Center and Mr. Masayoshi Hayashi of the Yokosuka City Museum for providing references.