The Sun-Dial Shells - Family Solariidae

THE SUN-DIAL SHELLS - FAMILY SOLARIIDAE. Shell spiral, depressed, conical, top-shaped or flat; aper ture angular; lip and columella simple; umbilicus wide, deep, usually with scalloped margin; lining not pearly; operculum spiral. Animal with large oval foot, notched in front; the eyes on the bases of the stout tentacles; radula with spiny teeth; jaws present.

Genus SOLARIUM, Lam.

Shell a regular, depressed cone, with an angular edge; sculp ture elaborate, close, strong, crossing the spiral ridges forming patterns in colours. World-wide genus in warm seas.

The Granulated Shell (S. granulatum, Lam.) found from North Carolina to the West Indies, and from Panama to Lower California, is finely checked by the crossing of spiral and radiating ridges, so as to have raised granules all over its upper surface. The flat base has them enlarged to nodules as it closes in to the narrow umbilicus. The surface is china-like, the whorls purplish, the upper edges white, and decorated with large brown dots in a single row. The largest specimens are about two inches

across.

S. verrucosum, Phil., is one to two inches across, with creamy yellow ground marked with numerous short streaks of brown. The umbilicus is narrow and has prominent teeth. This species may be a form of S. granulatum. West Indies.

The Oriental Sun-dial Shell (S. perspectivum, Linn.) is a depressed cone with angled margin and flat base. Its whorls have a spiral depression below the sutures; this also is seen on the basal coils, and in the broad umbilicus. Narrow ridges on each side of the depression are marked with brown spots. The ground colour is yellowish brown or ashy purple. Cloudy oblique bands cross the median surface of the whorls. Diameter, 2 to 5 inches. Indian Ocean, Pacific Ocean, China to Australia.

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