1. Misaki Marine Biological Station, The University of Tokyo, 1024 Koajiro, Miura, Kanagawa 238-0225, Japan (e-mail: )
2. Graduate school of Marine Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo 108-8477, Japan
3. Department of palaeontology, Natural history museum Luxembourg, 24 Rue Münster, 2160, Luxembourg