Hours: Monday through Friday: lunch, 11:30 a.m. to 2:30 p.m.; dinner, 5 p.m. to midnight (at the "Underground" bar, to 2 a.m.). Saturday and Sunday: brunch, 10:30 a.m. to 3 p.m.; dinner, 5 p.m. to midnight. Prices: Dinner entrees: $7.50-12.50. Hours: American Express, Carte Blanche, Diner's Club, MasterCard, Visa.

A few years ago the taverns along the two blocks of Pennsylvania Avenue east of the Library of Congress were nearly interchangeable: shellacked blond wood bars specializing in bleu-burgers and London broil, and Capitol Hillies intent on their own shellacking.

But in recent years the Four Musketeers have given up the one-for-all style. Jenkins Hill has acquired an upscale upstairs named Yolanda's, Mike Palm's has been taken over by Timberlake's, Duddington's has shucked the burgers for raw-bar chic, and only the Hawk and Dove retains the funk of yore.

In an attempt to net the newly self-conscious young professionals who haunt the neighborhood, Duddington's has tumbled to seafood in a major way.

Clams on the half shell, steamed and casino'd; oysters Rockefeller, Commander and Bienville; crab gumbo'd and marinated -- and these are just some of the appetizers.

But the move from turf to surf has left the kitchen a little unsteady on its sea legs. Dinner at Duddington's is like a congressional bill in conference: There may be a few bones to pick, but swallow hard and play up the sweet parts.

The menu is predictable, although the execution is erratic. "Bay country crab soup" is more like low-country gumbo: fragrant and filling, but kerneled with corn and peas, a Brunswick stew with crab meat stirred in. The chowder is enigmatic, filled with the sweetest, plumpest clams but thickened to the flour gravy stage.

Oysters Rockefeller are quite pleasant, though not precisely traditional. Sweet fresh spinach is topped with chopped onion (slightly sauteed but still with a bite), oysters, and strewn with hollandaise.

Since the oysters Commander presumably are named after the Commander's Palace in New Orleans, which claims to have invented the Rockefeller recipe, they remain a mystery.

Spiced shrimp are another mixed blessing, masterfully tangy but overcooked. The "marinated crab meat" salad is a mini-deli platter, with sliced onions and hard-boiled eggs around a heap of crab over onions and all doused with vinaigrette.

Main courses include the requisite shrimp stuffed with crab, Maryland crab cakes, flounder stuffed and baked or grilled, shrimp and crab Norfolk and pan-fried oysters.

There also are a couple of specials each night, which may merely lower the price of a standard dish, such as garlic-sauteed scallops down to $6.95 from $7.50, or introduce a wild card, such as London broil in brown gravy. The scallops were swimming in the flavorless oil often called drawn butter; the steak was grill-seared and respectable, except for the heavy sauce.

By far the best bite has been the steamed lobster -- a special, not a standard -- that, when ordered undercooked, was correctly delivered.

The kitchen is sailing along with the seafood, but the vegetables are a virtual wreck: raw, crunchy french fries and overblown, undercooked broccoli and, in the midst of asparagus season, completely inedible stalks: fat, cooked to mush inside and still wooden outside.

The other low spot is the bread, which once seemed a couple of days old and another night seemed positively venerable.