To the editor:

"So what did you talk about?" We expect that when we return from our coffee club. Politics? Movies? Last night's supper? How about tabby? No, not cats.

George had been to the Georgia coast and brought a postcard of St. Simons with a picture of the 104-foot lighthouse built of tabby. The senior member of our fraternity spoke for all of us: "What is tabby?"

We had no dictionary, but one in the group had learned when in St. Augustine, Fla., that tabby is the mix of crushed oyster shells and gravel used in paving roads and making lighthouses. I would not have slept well had I not learned that before bedtime. At the moment, the definition of "tabby" was my greatest imperative. I went to sleep knowing one more word.

I read an encyclopedia essay on oysters and studied a cross section of one which satisfied my appetite. Ancient Greeks, if they wished to vote against a citizen, would make their wishes known in that pre-paper age by scratching a negative mark on an oyster shell and would thus "ostracize" some luckless Athenian. Frank recalled that when he was in the New Hebrides 50 years ago, island roads were paved with crushed oyster shells. And I recalled the weekly 50-pound bag of oyster shells we gave to our hens if we didn't want soft-shelled eggs.

PETER HILTY

Cape Girardeau