The Siphon Shells Family Siphonariidae

THE SIPHON SHELLS FAMILY SIPHONARIIDAE. Genus SIPHONARIA, Blainv.

Shell patelliform, apex sub-central, posterior muscle scar horse-shoe shaped, divided on the right by a deep siphonal groove. Animal with broad two-lobed head; no tentacles; rudimentary branchim form triangular folds of the lining membrane of the mantle. Marine mollusks chiefly of the Tropics, living attached to rocks between tide marks, or if higher, where they are dashed occasionally by spray.

S. gigas,

Sby., has a solid, porcellanous shell, polished within and shaded to black at the margin. Exterior dingy, thrown into

many sharp-edged plaits, becoming worn with age. Length, 2 inches.

Habitat.— Panama.

S. alternata,

Say, has a backward pointing beak, drawn almost as far from the centre as the margin of the shell. Fine lines sculpture the basal half of the cone. Colour brown, with radiating lines of white. Base oval. Diameter, A- inch.

Habitat.— East Florida.

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