The genera Trigonostoma Blainville, 1827 and Scalptia Jousseaume are clearly distinguished: Trigonostoma has a triangular aperture, two columellar folds, the spire strongly to extremely scalate, and a wide, open, very deep umbilicus generally reaching the protoconch. Scalptia has been used to group a rather wide variety of shell forms more or less similar to Trigonostoma.