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The Castor Bean Shells

Genus RICINULA, Lam.

Shell ovate, solid, usually with spiny processes on the numerous varices; aperture long, narrow, toothed; canal short, oblique; columella wrinkled; operculum horny, thin, semi-lunar. Includes thirty species, inhabiting coral reefs among Polynesian Islands.

This genus, much like Purpura, contains also a sub-genus named "mulberry shells." The compact shape and spiny or lumpy surface give reasonableness to the common name.

The Bristly Castor Bean Shell (R. horrida, Lam.) is studded with stout black tubercles on a white ground. The flaring outer lip and the exceptionally wide columella are tinged with violet. The lip bears strong inner teeth; the columella, cross folds below the middle. Length, 1 to 1 3/4 inches.

Habitat.--Hawaiian Islands, Philippine Islands.

The Fingered Castor Bean Shell (R. digitata, Lam.) has long finger-like processes on the lip. Its spiny exterior is colourless; the aperture, orange-red. Length, 1 1/2 inches.

Habitat.--Central Pacific Islands.

The largest species is R. hystrix, Linn., a ponderous shell, with flattened spire and broad shoulder, tawny brown, set with stout, short fingers. The aperture is small and round; the flaring lip and columella are rose-coloured. Length, 1 1/2 to 2 1/2 inches.

Habitat.--Central Pacific Islands.

The Mulberry Shell (R. morus, Lam.) is well named. Its white spire is covered with rounded black (rarely white) nodules. The aperture is violet. Length, 2/3 to 1 inch.

Habitat.--Polynesia.