Twelve molluscan species were identified from the middle Miocene in Kenbuchi-cho, northern Hokkaido, which is assigned to the Denticulopsis lauta Zone (NPD 4A, 15.9-14.9 Ma). The molluscan assemblage includes some warm-water taxa such as Glycymeris cisshuensis and Liracassis japonica. The occurrence of the warm-water taxa indicates that warm water mass prevailed in northern Hokkaido. According to the molluscan evidence, northern Hokkaido was in a temperate marine zone during the early middle Miocene.
