Lynceid conchostracans of the order Laevicaudata in East Asia are reviewed. Validity of the three older species, Lynceus mandsuricus Daday, Lynceus biformis (Ishikawa), and Lynceus dauricus Thiele, is examined and discussed. Two species among them were acknowledged but L. dauricus was synonymized to L. biformis and redescribed and illustrated in the present paper, based on the materials collected from the rice-fields at 15 localities in Korea.