SOURCE.—O'strea virginia'na and O. edulis, which excrete a
calcareous bivalved covering or shell, and inhabit the shallow
coast water of the Atlantic and Indian Oceans.
DESCRIPTION.—External surface rough, inner surface smooth and
white, the two toothless, hinged valves made up of imbricate,
foliaceous layers, presenting, when closed, an irregularly
rounded, oblong, or ovate form. CONSTITUENTS.—Largely calcium
carbonate, there being only 4 per cent. or less of animal matter
present and a small percentage of silica, alumina, magnesia, and
calcium phosphate and sulphate. USES.—Antacid. The shell, to be
used, should first be thoroughly purified and washed in boiling
water. Dose: 5 to 15 gr. (0.3 to 1 Gm.). A Manual of Organic
Materia Medica and Pharmacognosy, 1917, was written by Lucius E.
Sayre, B.S. Ph. M.