THE WIDE-MOUTHED SHELLS - FAMILY STOMATELLIDAE Shell small, pearly within, flattened, limpet-like or ear shaped and spiral, but without holes or slit.
This family lives in tropical regions of the Pacific Ocean. Classification is likely to need revision as the living mollusks are studied. Few have ever been seen.
Within this family a series of genera show the gradations between the coiled top shell forms, with narrow mouths, closed by an operculum, through widening ear shell forms to the limpet form in which the spiral disappears. The bearing of this chain
of evidence upon the problems of evolution among mollusks is obviously important.
Stomatella has a depressed spire, few whorls, a regular top shape and an operculum. Stomatia has a short spire and no operculum. The animal is too large for the shell. Gena is ear shaped like Haliotis. Broderipia illustrates the limpet form of shell in this family. The shell has an apical hook at the posterior end. It is shaped like a sugar scoop.
220