Page:American Seashells (1954).djvu/455

Rh similar to the Pacific Coast species. Inch-long, brownish specimens are fpund in the crevices of coral boulders below low-water mark to several fathoms. Larger, more whitish specimens are found clinging to iron wrecks. Moder- ately common. P, decipiens Philippi. See plate 38b. SuperfavTily OSTREACEA Family OSTREIDAE Genus Ostrea Linne 1758 This genus used to include all of the oysters, but today several valid genera are recognized, so that only three American species are included in true Ostrea. These are O. eqiiestris Say and O. permolUs Sowerby from the Atlantic Coast and O. hirida Carpenter from the Pacific Coast. The Euro- pean oyster, O. ediiUs Linne is also in this group. All of these oysters are relatively small. The eggs are fertilized and developed within the mantle chamber and gills. Usually around one million eggs are produced at one spawning. The prodissoconch hinge is long, the valves symmetrical. In the adults, the muscle scar is near the center of the shell and is not colored. Ostrea equestris Say Crested Oyster Plate 28c North Carolina, Florida, the Gulf States and West Indies. I to 2 inches in length, more or less oval, and with raised margins which are crenulated. The attached valve has a flat interior with a rather high, ver- tical margin on one side. Interior dull grayish with a greenish or opalescent- brown stain. Margin sometimes stained a weak-violet. Not very abundant except in some Florida bays. It lives in water that is much saltier than that in which virginica lives. Also named spreta Orbigny. O. cristata Born is quite different and is limited to South America. Ostrea pons Linne 'Coon Oyster Plate 28d Florida, Louisiana and the West Indies. I to 2 inches in size. The radial plicate sculpture and corresponding sharply folded valve margins are characteristic of this intertidal species. Inner margins of valves closely dotted with minute pimples for nearly the entire circumference of the valves. Muscle scars located well up toward the hinge. Beaks somewhat curved. Interior translucent-white, exterior usually purplish red. Frequently elongate and attached to stems of trees by a series of clasp- ing projections of the shell, but may be also oval in shape. O. rubella and O. limacella Lamarck are this species. O. jolimn Linne is a Philippine species.