The author wishes to express her gratitude to Dr. Naotune Watanabe, an emeritus pro fessor of the Department of Anthropology, Faculty of Science, The University of Tokyo, for his guidance and encouragement in the course of this study. She also wishes to express her thanks to the Paleontological Laboratory, Geological Institute, The University of Tokyo, for permission to use scanning electron microscope, and to the Fisheries Ex perimental Station of Kumamoto Prefecture for their kind arrangements for field experiments.

The author is indebted to the Archaeological Institute, Keio University, to the Archaeological Laboratory, Komazawa University, to the Education Committees of Tokyo, Yokohama, Ichikawa, Matsudo, Funabashi and Sakura Cities and to the Cul tural Properties Center of Chiba Prefecture for making facilities available for the ex cavation of the shell-midden samples.

I am also grateful to Prof. Masuoki Horikoshi of the Ocean Research Institute of The University of Tokyo and to Dr. Kiyotaka Chinzei of the Paleontological Laboratory of the Geological Institute of the same University, for their instructions in the preparation of the manuscript, and to Mr, C. T. Keally of Sophia University for his kind revision of the English in this paper.