Reprinted from yesterday's late editions.

The Rive Gauche in Paris is that side of the river where the intellectuals and poor students used to hand out and where the restaurants kept body and soul more or less together with delicious economical dishes such as stewed gizzards and escarole, things like that.

In Washington, on the other hand, the Rive Gauche is as fancy as any restaurant in town and they run to salmon delicately glazed - a bit stingy with the truffles - and serious eaters like Art Buchwald, the Kissingers and so forth.

To celebrate the restaurant's 20th year, Tony Greco, owner with Michel Burkle and Michel Laudier, Sunday night invited about 200 current customers for a free feed.

It was a more valuable invitation than most in the capital, if you have priced sea urchins lately.

The "little animals from France" as someone called them were identified, after some persistence, as sea urchins. They sat in a ferocious pile, until servers sliced off their top, revealing a pathetic (and delicious, one is sad to report) soft creature inside; in volume, less than an oyster but in flavor approaching an anchovy.

"I've stepped on them," said a serious man. "Imagine eating them." Well, that is a capital for you.

"You have noticed," said Michael Halberstam, a physician, "the two levels of guests here, those who cleave to Tony Greco and those who date from Jeannine Cusson."

Cusson, for years the manager of the place, was and is a great regal beauty, more electric about the eyes than most beauties, and a tremendous pain in the neck for many.

She had notions about who should get good tables and who should not, and those who wound up dim corridors near the alley (in a manner of speaking) never sang her praises.

"Some bungler spread the word that Godfrey McHugh, the Kennedy aide once took Mrs. Merriweather Post to the restaurant and Jeannine refused to seat them because Jeannine didn't like Godfrey. What nonsense. It wasn't McHugh at all but somebody else. Jeannine was very fond of the McHughs," said Barbara La Franceaux a guest ensconced at a table upstairs and working steadily through a plate of paradise stuff.

"Well, I phoned Godfrey," she said, "and got that straight. Don't you like to get the loose ends together, sort of tidy up, the compost pile," she said, happy to have lit one candle, at least, to the dark world of Washington rumordom.

As for Cusson herself, she was seen hugging Max Cleland, new administrator. For the Veterans Administration, then was spotted heading madly toward the great carve winged horses made of ice and bearing treasures.

"I just dropped in for a drink," said Cusson, aghast that she had missed the sea urchins which by now were all gobbled up. She still loves to eat at the restaurant, which is no longer hers to break hearts at (many a man has wept at the table he got, but no tears moved. Cusson from her standards as she saw them).

As for "loftiness," she said, "When you deal with the public, you may as well realize you aren't going to make everybody happy, and that's that." Even Presidents have been slow to learn it, of course.

A portrait of Nancy Kissinger by Jose Fahri-Canti adorned a wall, along with portraits of other customers lent for the occasion.

A great crowd developed, naturally, around the lobster cocktails and caviar and lump crabmeat, but the haze (for many smoked) parted to reveal additional calories and stunning women - writer Vicki Ostrolenk in white, for example.

The owner's wife, Senie Greco (her real name is Acenath, named for her great-grandmother who was named for the wife of Jacob in the Bible, who dreamed of seven fat years, among other things), was too busy to eat.

"I've had one martini, and that will do me," she saidd, surveying the crowd. "I'm not much of a cook, actually."

"Why, I grew up," interrupted Mix Beard, a business associate of her husband, "eating this lady's leftovers."

"Well," said Senie Greco, not unmindful of the compliment, "I do feel uneasy when Tony comes home and all I have is a pot roast plain food."

"Impossible to beat a pot roast," said a fellow gulping some crabmeat.

The owner's daughters, Anne and Terry, were there but not Tommy, the 19-year-old son.

"He's at a concert," said his mother. "He couldn't care less for all this. He's going off in the morning on the Appalachian Trail. Imagine walking for two months - yes, two whole months - to find yourself. Well, I think the young have a lot to teach us."