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  • José H. Leal

Shell of the Week: The Beaded Sundial

Heliacus bisulcatus (d’Orbigny, 1842), is a marine snail of the sundial family Architectonicidae. that may reach about 12 mm (about 0.5 inch) in diameter. The characteristic, donut-shaped shell has a flattened spire and a sculpture of five rows of squarish beads per whorl. The shell periphery (the “outer rim” of the shell) has two prominent rows of beads. The umbilicus is wide and deep. Color is brown to dull-cream. The species has a very broad distribution from North Carolina to Florida and the Caribbean, Gulf of Mexico (in deeper water), Bermuda, and both sides of the tropical Atlantic Ocean, including West Africa.


The Beaded Sundial, Heliacus bisulcatus, from off Flagler Beach, Florida. Photos by James F. Kelly.