They fall into two groups: flat (Ostrea) and cup-shaped (Crassostrea).    From Wordnik.com.  [4 Coastal Mariculture] Reference

There, they grow both the rock oyster and the rarer Belons (Ostrea edulis), which possess an intense mineral flavor.    From Wordnik.com.  [Oysters Come Back in Vogue] Reference

There are two main kinds of oysters found in the British Isles: the flat, or native, oyster (Ostrea edulis), most famously grown among the beds in Whitstable, Colchester and Helford; and the rock, or Pacific, oyster (Crassostrea gigas), which was introduced commercially into Britain in the 1960s.    From Wordnik.com.  [Oysters Come Back in Vogue] Reference

Ostrea ovato-cuneiformis; p.  358, pl.  4, fig.  2.    From Wordnik.com.  [Lamarck, the Founder of Evolution His Life and Work] Reference

Imperfect specimens of an Ostrea occur in it, but too much broken to be determined.    From Wordnik.com.  [Report of the North-Carolina Geological Survey. Agriculture of the Eastern Counties: Together with Descriptions of the Fossils of the Marl Beds] Reference

Gryphaea is the most abundant -- an Ostrea, Turratella, Ammonites, small bivalves, Terebratulae (?).    From Wordnik.com.  [More Letters of Charles Darwin — Volume 1] Reference

Ostrea edulis dwells in the European oceans, frequent at the tables of the luxurious, a living repast!.    From Wordnik.com.  [The Temple of Nature; or, the Origin of Society A Poem, with Philosophical Notes] Reference

"We felt like we were mentally and physically prepared to play, but unfortunately it just didn't work out for us today" Ostrea said.    From Wordnik.com.  [The Rebel Yell] Reference

Ostrea radians and O. sellaeformis belong also to the miocene beds, together with the Anomia ephippium; the latter is always broken.    From Wordnik.com.  [Report of the North-Carolina Geological Survey. Agriculture of the Eastern Counties: Together with Descriptions of the Fossils of the Marl Beds] Reference

At Blackrock the lowest is known by its fossils: the Exogyra costata, Ostrea falcata, Belemintes Americana, and casts of the cucullea vulgaris.    From Wordnik.com.  [Report of the North-Carolina Geological Survey. Agriculture of the Eastern Counties: Together with Descriptions of the Fossils of the Marl Beds] Reference

I think he's probably referring solely to native oysters (Ostrea edulis), which spawn in the summer months and become thin and unpalatably creamy rather than actually dangerous.    From Wordnik.com.  [The Guardian World News] Reference

In the afternoon the women collected for me a considerable number of shells, several species of Cardium, Citherea, Ostrea, &c., all edible, and the last very good, though small.    From Wordnik.com.  [Townsend Chapter 16] Reference

Could we obtain a deep section of the bottom, we should find beds of Ostrea edulis and Cardium edule, then a layer of Zostera marina with fresh-water fish, and then a bed of Mytilus edulis.    From Wordnik.com.  [The Earth as Modified by Human Action] Reference

It all changed during the Eocene period when all we had was about 5 different species of shark, Ostrea (oyster shells), some clam shells (Cullculae Gigantis), and worm tubes. yes, I'll take my reward in US dollars and some gold.    From Wordnik.com.  [Latest Articles] Reference

There occurs in great numbers a species of small Pecten, -- some of the specimens scarce larger than a herring scale; a minute Ostrea, a sulcated Terebratula, an Isocardia, a Pullastra, and groups of broken serpulæ in vast abundance.    From Wordnik.com.  [The Cruise of the Betsey or, A Summer Ramble Among the Fossiliferous Deposits of the Hebrides. With Rambles of a Geologist or, Ten Thousand Miles Over the Fossiliferous Deposits of Scotland] Reference

The green sandy beds at Mr. Flowers, beneath his shell marl, contain a few specimens of the Ostrea falcata, and at one or two of the bluffs above Mr. Flowers, on the Cape Fear, I found the vertebra of a large saurian, which I am confident belongs to the green sand, but in both of these cases their occurrence in these beds may have been accidental.    From Wordnik.com.  [Report of the North-Carolina Geological Survey. Agriculture of the Eastern Counties: Together with Descriptions of the Fossils of the Marl Beds] Reference

These consist entirely of living species; but, in the first place, the common eatable oyster is among them, attaining its full size, whereas the same Ostrea edulis cannot live at present in the brackish waters of the Baltic except near its entrance, where, whenever a north-westerly gale prevails, a current setting in from the ocean pours in a great body of salt water.    From Wordnik.com.  [The Antiquity of Man] Reference

Olympia Oysters (Ostrea lurida).    From Wordnik.com.  [Oysters Come Back in Vogue] Reference

London was once an oyster-bed), that in the chalk below, though it contains several species of Ostrea, the shells are diffused promiscuously throughout the general mass.    From Wordnik.com.  [The Cruise of the Betsey or, A Summer Ramble Among the Fossiliferous Deposits of the Hebrides. With Rambles of a Geologist or, Ten Thousand Miles Over the Fossiliferous Deposits of Scotland] Reference

Ostrea edulis dwells in the.    From Wordnik.com.  [Canto II] Reference

Ostrea isognomum Wiakbraaii. wen.    From Wordnik.com.  [Allgemeines Polyglotten-Lexicon der Naturgeschichte mit erklaerenden Anmerkungen] Reference

European Flat Oyster (Ostrea edulis).    From Wordnik.com.  [Oysters Come Back in Vogue] Reference

Ostrea.    From Wordnik.com.  [More Letters of Charles Darwin — Volume 2] Reference

Ostrea radula.    From Wordnik.com.  [Allgemeines Polyglotten-Lexicon der Naturgeschichte mit erklaerenden Anmerkungen] Reference

Ostrea pallium.    From Wordnik.com.  [Allgemeines Polyglotten-Lexicon der Naturgeschichte mit erklaerenden Anmerkungen] Reference

Ostrea malleus.    From Wordnik.com.  [Allgemeines Polyglotten-Lexicon der Naturgeschichte mit erklaerenden Anmerkungen] Reference

Ostrea pleuronectes.    From Wordnik.com.  [Allgemeines Polyglotten-Lexicon der Naturgeschichte mit erklaerenden Anmerkungen] Reference

Ostrea).    From Wordnik.com.  [Allgemeines Polyglotten-Lexicon der Naturgeschichte mit erklaerenden Anmerkungen] Reference

Ostrea elongata -- Deshayes.    From Wordnik.com.  [Two Expeditions into the Interior of Southern Australia — Complete] Reference

Ojster ------------- Ostrea.    From Wordnik.com.  [The geographical and historical dictionary of America and the West Indies : containing an entire translation of the Spanish work of Colonel Don Antonio de Alcedo ... with large additions and compilations from modern voyages and travels, and from original and authentic information] Reference