An individual of Climaconeis inflexa was obtained from Sagami Bay. It increased the number of cells by laboratory cultivation in enriched seawater in March 1985. This diatom also showed circular movement on agar flat in Petri dishes. Another individual of this diatom was found in a fixed population collected from Hachijo Island, the Izu Islands of Tokyo Metropolis, in August 1986. The number of striae in valve face of those specimens observed with TEM was 32-34 in 10 pm, which is far greater than the description by Cox (1982).