M. fragarioides. The strawberry-shaped Monodonta.
Species more or less globular, of which the columella, almost straight, offers but a little obstacle to its junction with the margin.
4. Turbo. The Turban Shell. Thirty-four species.
Distinguished from the Monodonta by never having the columella truncated at the base; and from the Trochus by being solid, with the whorls constantly convex and never flattened. Like the Trochus, when decorticated, the Turbo exhibits splendid pearly, gold, or silver irridescent colours.
Shell thick, pearly in the interior; depressed, conical, or sub-turreted; umbilicated or not, little or not carinated at its circumference; aperture round or little depressed; the middle of the external edge not bent, but sometimes hollowed or sloped in some part; the edges rarely joined by a callosity; the columella arched, rarely twisted, and not truncated at the base; operculum calcareous or horny; the spire visible externally in the latter and interiorly in the former; the exterior often thickened and curved.
Turbo marmoratus.
T. imperialis.
T. torquatus.
T. diaphanus.
T. rugosus.