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The Coffee-bean Shells

Genus TRIVIA, Gray

Shells cross-ribbed, roundish, with a concavity on the inner face of the ribbed columella. Mantle covered with papillae; foot extended far out behind the shell.

The Coffee-bean Shell (T. pediculus, Linn.) is a pinkish button-like shell, tinged with brown and marked with six large black spots on the back, three on each side of the median depression which runs lengthwise of the shell. Strong cross ridges encircle the shell, and continue into the aperture. Length, 1/4 to 2/3 inch.

Habitat.--Florida, West Indies.

The Four-spotted Coffee-bean (T. quadri-punctata, Gray) is a bit smaller, with finer cross ridges, purplish, with four small but distinct black dots along the median groove.

Habitat.--Florida Keys, West Indies.

The California Coffee-bean Shell (T. Californica, Gray) is about the shape and size of a large grain of coffee. The dorsal depression is shallow, the twelve ribs are white and somewhat far apart. The purplish brown of the shell is dull beside the vivid scarlet of the body. When the creature extends its long tentacles and proboscis in front and its broad foot behind, the shell is swallowed up by the mantle, and makes the bright red dull by its purple showing through.

T. Solandri, Gray, is twice the size of the previous species, with stronger sculpture, and a paler purple between the ribs. There is an additional tooth between each two ribs of the outer lip.

Habitat.--Santa Barbara, Cal.

T. sanguinea, Gray, has a bloody spot on the middle of the back. The ground colour is purplish, the ribs whitish. Length, 1/3 to 1/2 inch.

Habitat.--California southward.

The European Cowry (T. Europaea, Montagu) is closely ribbed, the ground colour flesh pink, the base white. The body is bright yellow, brown and pink. The mantle is broad, its surface covered with papillae, brownish yellow or white, often dotted with scarlet and purple. Length, 1/2 to 3/4 inch.

The animal is very active but also shy, quick to withdraw into the shell at the first sign of danger. "Nun" and "Stick-farthing" are names by which this plentiful mollusk is known on some parts of the English Coast. "Gowry" was the old form of "Cowry."

Charles Kingsley describes this mollusk as hanging a few inches below a rock to which it has attached itself by a glutinous thread. He also saw it float in an aquarium by means of a glutinous bubble to which it had a similar thread attachment.

The distribution of this species on stony bottoms from low water to 100 fathoms depth, and from the Mediterranean to the Norwegian coasts, indicates unusual powers of adaptation to different temperatures and depths. The largest forms occur farthest north.