Police divers and volunteers with the National Aquarium in Baltimore performed a rare rescue Labor Day of a bottlenose dolphin from the beach of Assateague Island.

The dolphin, diseased and badly wounded in a shark attack, is of a breed that lives miles offshore and is rarely found alive near the coast, according to officials at the aquarium, where the 420-pound, 10-foot mammal is being treated.

"She's probably an older animal that either has a serious disease or was starting to weaken from old age," said David Schofield, marine animal rescue program coordinator at the aquarium.

Lagging behind her fellow dolphins, she was left vulnerable to attack and likely struggled to reach safety on shore.

Rangers on a routine patrol of Assateague National Seashore found the dolphin lying on the sand Monday. Local marine rescue volunteers and members of the Ocean City, Md., police dive team placed her in an ice-cooled tank and drove to Easton, Md., where aquarium officials picked her up and took her to their marine animal hospital in Baltimore.

The aquarium has a special carrier for such purposes--a truck-towed frame holding a bag lined with foam. The dolphin lies inside the bag, which is kept dry and cool.

Although the aquarium aids in the rescue of two or three stranded creatures a month, including whales, seals and sea turtles, officials there rarely see bottlenose dolphins, which are known for their rounded foreheads and well-defined snouts.

The female dolphin--likely in her late teens, which is old for a dolphin in the wild--had been ferociously attacked by sharks that left deep wounds around her abdomen and genital region, Schofield said.

But even before the attack, she was apparently suffering from a slew of possibly geriatric illnesses that may have caused her to fall behind her "pod," or social group. Schofield said the dolphin has a stomach infection, and blood tests indicate she might have liver problems.

In addition, he said, "the breath from her blowhole is very foul, which suggests infections."

Schofield noted that it is common for dolphins to beach themselves when they are in trouble, behavior that some scientists believe is an instinct left over from millions of years ago when dolphins lived on land. "They are air-breathers, and they want to support their head over water," he said.

Yesterday, the dolphin was resting on a stretcher placed in a water-filled tank at the aquarium. Veterinarians were allowing her to swim a little, for exercise, Schofield said.

The dolphin remains in serious condition, he said. "It's often an uphill battle to try to save one of these animals."