Abstract
The present paper deals with the taxonomy and radular characters of some members of the genus Drupella, based on examination of Reeve's typological specimens of Triton angulatus and Ricinula dealbata. D. minuta n. sp. is described from the Ryukyu Islands. The rachidian teeth of the radula of this species exhibit remarkable changes in the number of the cusps, in the form, in the L-R row ratio, as well as in the size, with growth regardless of the sex. Another species is referred to D. eburnea (Kuster, 1862) on the basis of the original figure and the description, for specimens from the Ryukyu Islands previously erroneously assigned to D. dealbata (Reeve, 1846), which is a junior synonym of D. fragum (Blainville, 1832).
