Shell. Oval, more or less ventricose; the first whorls of the spire rounded into a teat; aperture generally much longer than wide and sloping anteriorly; the right edge bent outwardly, entire and soft; the columellar edge garnished with large folds more or less oblique, and slightly varying in number with age. Found chiefly in the seas of the Torrid Zone. Forty-four species.

4. Genus Marginella. Pl. [XII].

Animal. Oval, involuted; foot elliptical, very large, and widest in front, where its edge presents a transverse furrow; head small, distinct, with two long, very sharp tentacula, the eyes at the external part of their base; mouth provided with a trunk.

Shell. Smooth, polished, oval-oblong, a little conical, with a short mammelonated spire; aperture somewhat narrow, slightly oval on account of a light curve of the right edge, which is dilated outwardly; the columellar edge marked with three oblique distinct folds. Inhabits the Indian Ocean. Twenty-four living species and nine fossil, according to Defrance.

5. Genus Volvaria. Pl. [XII].

Animal. As above.

Shell. Cylindrical, convolute; spire obsolete or concealed; aperture narrow, extending the whole length of the shell, with one or more folds on the lower portion of the columella. Inhabits the Indian Ocean. Seven species.