10. Genus Eburna. Pl. [XII].

Animal. Entirely unknown.

Shell. Oval or elongated, smooth; spire pointed, its whorls as if softened off; aperture ovate, elongated, widely notched anteriorly; the right margin entire; columella callous posteriorly, umbilicated, and subcanaliculated at its left side; an operculum. Found in the Indian and South American seas. Five species.

11. Genus Terebra. Pl. [XII].

Animal. Spiral and high; foot oval with a transverse anterior furrow, and two lateral auricles; head bordered with a small fringe; tentacula cylindrical, terminating in a point and very distant; eyes indistinct, situated at the foot, and at the external side of the tentacula; mouth without proboscis; tube of the respiratory cavity very long.

Shell. Without epidermis, ovate, with a pointed spire, low, or subturriculated; aperture wide, oval, with a strong slope anteriorly; lower end of the columella twisted. Found in tropical seas. Twenty-four species.

FAMILY XX.
Columellaria. Five genera.