He was a bold man that did first eat an oyster . - Jonathan Swift

Nobody knows who ate the first one, but the Romans served them at their orgies. The more serious-minded Greeks ate them, too, and then used the shells for voting - etching the candidate of their choice in the mother of pearl on the inside of the shell. The Japanese dove for them. The American Indians ate so many they created those huge trash heaps of shells that archeologists find so fascinating. The Celts pursued them with a fierce passion and passed the habit on to their scattered progeny. In 1840, the French Navy had to guard the oyster beds of Arcachon Bay with gunboats, so grave was the depletion problem.

The caveat about eating oysters in R-less monthe is part an old-wives' tale, part a precaution dating from the days before refrigeration, and part a conspiracy by conservation authorities who want time for seeding. In most harvesting areas, including the Chesapeake, there are private beds that have no seasonal restrictions and supply oysters all year round.

There are about a hundred different species of this edible bivalve mollusk, and lots of subvarieties according to where the oyster is spawned. Oysters stay in one place until they are harvested, funneling about 40 gallons of water a day through their shells. The water, with its microscopic nutrients that make the oyster grow, determines how it tastes. Thus, though marennes, belons and Colchesters are all of the European oyster species, their partisans insist they can tell them apart.

The local species, Crassostrea virginia , lives up and down the East Coast from Nova Scotia to Galveston Bay, but don't try to tell a Long Islander and a Virginian that they're harvesting the same kind of oysters. In an oyster stew, a Hangtown Fry, even in Oysters Rockefeller, cooking minimizes regional differences. But I happen to like them raw - probably because it's a word with an R in it.

George Hannon, who owns a raw bar in the Annapolis City Market, serves Long Island oysters on the half-shell - until there's an adequate supply of Chincoteagues.

"Salinity is the major factor," Hannon says. "The Bay isn't very salty, so Bay oysters don't have that salty tang. Chincoteagues do, because Chincoteague Bay is on the ocean side."

Reliable sources say that some watermen take Chesapeake oysters and dump them into Chincoteague Bay just long enough for the oysters to acquire that salty tang and to be sold as Chincoteagues. Recently an intrepid team of oyster-eaters went on a salty search of raw bars (in case you are a recent refugee from California, these are not topless places) in search of the true Chincoteague oyster.Here are the results of that unscientific investigation:

The methodology consisted of visits, during the course of one extended evening, to four oyster bars. After registering initial impressions of both ambiance and oyster quality, the four members of the team - who have more than a century of oyster-tasting experience among them - wrapped one oyster apiece in a baggie, labeled it as to bar, and placed it in a designated pan in the back of the station wagon. At the end of the evening, oysters from each establishment were compared. However, during the drive from bar to bar, some of the oysters inevitably lost some liquor. And some of the tasters, despite numerous admonitions, inevitably drank too much wine, which may have muddled judgment.

JOHAH'S OYSTER KITCHEN - Hidden behind the unpromising cinder-block exterior of the Hyatt Regency Hotel at 400 New Jersey Ave. NW is Jonah's Oyster Kitchen, an attractive place made of good, solid material like brass, copper, etched glass and a marble oyster bar.

We ordered a dozen oysters on the half-shell ($4.95) and half a dozen oysters Muscovite, which are raw, on the half-shell but napped with a creamy horseadish sauce and topped with black caviar. There was no house wine available in carafes, so we had to settle for the cheapest bottle on the wine list - Wente Bros. California Chablis, at $9.

As the waiter shucked our oysters behind the bar he told us they were from Long Island. Where on Long Island?

"It is near New Jersey," said the waiter, a medical student named Uyen from Vietnam, which, I suppose, is near Pakistan.

After he finished shucking each oyster, Uyen ran it briefly under a fresh-water tap. This probably washed away any bits of shell, but it also diluted the salty tang slightly. Otherwise, the oysters on the half-shell were fresh, plump and juicy, and the Muscovite variety were also a delicious combination of tastes that enhanced but did not overwhelm the oysters.

Jonah's if full of touches of class. The lemons to squeeze on your oysters are wrapped in cheesecloth for your protection, and there are cloth napkins whose generous size impressed a British member of the tasting team. "Not one of those ridiculous ladies' handkerchiefs," he said approvingly.

At the end of the evening, Jonah's oysters were rated the second-best we had tasted.

CAPT. JACK'S RAW BAR - In the basement of The Greenery at 1144 18th St. NW is an attractive place filled with nautical antiques, a juke box, a barrel filled with oyster crackers and a highly polished wooden bar. We ordered a dozen oysters on the half-shell, at 30 cents apiece. Andy the bartender shucked them to order, occasionally interrupted by drink orders from the restaurant upstairs. The television above the bar was tuned to a baseball game. Andy didn't know the score, but every time a waitress from upstairs asked about it, he made a wild guess.

The oysters, which were from Long Island, were not much in demand, Andy tol us. More popular were the spiced shrimp, which he generously gave us free samples of.

Probably because the oysters were slow to sell, they did not seem very fresh. "Rubbery," "slimy" and "dry" were some of the tasters' comments.

THE DANCING CRAB - The Lng Island oysters here at 4611 Wisconsin Ave. NW. were not only the cheapest (at $2.95 a dozen), they were quite tangy and fresh, flawed only by bits of shell left over from the shucking process. The atmostphere is informal and slightly tacky, with ersatz Tiffany lamps and plastic forks, but the service is good. You have your choice of watching the aquarium behind the bar or the baseball game on television, and the bartender knows the score.

CRISFIELD SEAFOOD RESTAURANT - This Silver Spring mainstay, at 8012 Georgia Ave., erves "the kind of oysters we always serve: Chincoteaques." A baker's dozen on the half-shell cost $5, and was worth it - so fresh they almost jump when the lemon is squeezed on them.

Perhaps because Chincoteague Bay is closer than Long Island Sound, these oysters seemed juicier and tangier to us than the Long Islands. And the Crisfield is a pleasant place, next to a tire store in a non-descript area of Silver Spring where it has been run by the same family for 34 years. For almost that long, the owners hae been collecting beer steins; about 300 of them line the walls around the large, U-shaped oyster bar that fills the restaurant's main room. With the exception of the steins, the decor is extremely modest, running to heating pipes and coment walls.

There are at least three other raw bars that we didn't sample, for various reasons: McGUIRE'S (1330 Pennsylvania Ave. SE) and MASON'S (300 King St., Alexandria) were closed. McGuire's, which serves Chincoteagues, has a raw bar only during the week, but will start opening on weekends some time this fall; Mason's serves Long Island oysters but closes its raw bar at 11 even on a Saturday night; those who arrive at 11:15, as we did, are out of luck.

RIORDAN'S (3210 Branch Ave., Silver Hill) serves Bay oysters but was out of them; we were told they'd be in this week.