The genus Runcina (=Pelta) is a small group of the opisthobranchiate Order Cephalaspidea. The animals are mostly very small in size, too. The first record of the genus from our territory was made by me in 1937 (Runcina elioti BABA, from Amakusa). The present paper deals with the second form for which I am here going to give a new specific name. I am very glad to thank Dr. Huzio UTINOMI, of the Seto Marine Biological Laboratory, for the kindness shown to me in studying this rare and interesting species at Seto.