Abdomen, the belly.
Aculeated, furnished with, or ending in, prickles.
Acuminated, ending in a sharp point sharp pointed.
Adnate, adhering or growing together, adjoining.
Alated, winged, applied to the expanded lip of the Strombus genus, &c.
Ambitus, the circumference or outline of the valves.
Annulated, formed or divided into distinct rings.
Annulations, rings.
Antiquated, longitudinally furrowed, but interrupted by transverse furrows, as if the shell had acquired new growth at each furrow.
Aperture, the mouth or opening of the shell.