VIRGINIA BEACH -- With the hosing down of the tools -- a chisel, two meat hooks, a yardstick, a mallet, a hacksaw and three knives -- the necropsy was over.

The 375-pound female bottlenose dolphin that had washed ashore here Saturday night at about 9 o'clock was now just a catalogue number (WAM 214), a two-quart container of tissue samples floating in formaldehyde, several dozen bacterial, viral and toxicological culture samples, and seven plastic garbage bags full of remains.

Thus continued the scientific query into the mysterious death of yet another dolphin -- one of dozens that have died in the past six weeks from unknown causes that continue to baffle scientists.

As the beginning of the weekend brought dead bottlenose dolphins up on the beach at an alarming rate, eight to 12 a day, rather than the usual 10 to 12 a year, explanations continued to elude the scientists.

If answers are to be had, the small team of biologists gathered here in Virginia Beach hopes that WAM 214's tissue samples and cultures, which were sent Sunday night by express mail to the Department of Agriculture's National and Veterinary Services Lab, will provide some.

The lab, in Ames, Iowa, is to animals what the Centers for Disease Control in Atlanta is to people. And the biologists here -- Joseph R. Geraci, a specialist in marine mammal veterinary medicine and professor of pathology at the University of Guelph's Ontario Veterinary College; William McLellan, a museum technician with the marine mammal collection of the Smithsonian Institution, and Greg Early, assistant curator of fish and mammals at Boston's New England Aquarium -- look for preliminary, but not conclusive, lab results by midweek.

In a population of dolphins in the mid-Atlantic area that numbers 1,500 by rough estimates, the recorded loss of almost 150 represents a group "that's getting a real severe beating," said Early. The blight, which is striking the mid-Atlantic population of migratory bottlenose dolphins, favors no particular age group or gender, presents no readily discernible pattern of pathology, and is, as one of the biologists here puts it, "consistently inconsistent."

WAM 214 -- its gums and the roof of its mouth covered with shallow little ulcers and its lungs, swollen heavy and wet -- was one more piece of the puzzle.

But the information available from WAM 214 is, according to Geraci, one of the most promising, initial leads from a necropsy, an autopsy on a nonhuman subject. The dolphin was freshly dead and not as obviously ravaged as the other five dolphins already examined.

After a day spent on the phone, coordinating a diffuse network of municipal and federal agencies, volunteers, and technicians, or on the beach, crouched over the dolphin carcasses, performing necropsies while contending with a cluster of curious oglers, the sun, the sand, the surf and the flies, Geraci and his colleagues were readying themselves for a late dinner when a police car pulled into the parking lot of their motel. An officer brought the news: Another dolphin had washed up onto the narrow strip of sand down at 10th Street by the boardwalk. The word was that this was a fresh dolphin, not as most of the carcasses have been, too decomposed or mutilated to be valuable scientifically.

Geraci, Early, McLellan, Geraci's daughter Johanna, J. Thomas Whitman, curator of live exhibits at the Virginia Marine Science Museum, and Brian Gorman, public affairs officer for the National Marine Fisheries Service, sped down to the beach. In the back of Whitman's truck were two aluminum coffins: military transport cases, designed for humans but suitable in this situation for dolphins.

Somewhere in the center of a tight circle of almost 200 tourists, was the dolphin, intact and inert. To the untrained eye, only a small trickle of blood from its mouth offered any immediate drama. But for that, it could have been Flipper in dry repose.

"This is just about the freshest we've got," Geraci said. Then, pulling at a yellow rope tied around the dolphin's tail and pushing at its torso, the biologists positioned the mammal's body on the coffin lid, with its tail hanging over one end. Within minutes, a beach police officer was towing the coffin lid across the sand and the late-night beach crowd, in bathing suits and flipflops, was chasing quietly after it.

At the steps of the boardwalk, as the men hoisted the dolphin up into the air and moved toward a nearby pickup truck, a beach official shouted, "Ladies and gentlemen, give these folks some room. It ain't fun to slip and fall with this."

The plan -- to move the dolphin to a storage space at the Virginia Air Reserve National Guard, take some preliminary samples and measurements, put the carcass on ice and return to it in the morning -- was replaced by a scene of surreal detail: a midnight necropsy in a wooded area behind Building 238, a large garage that, lacking a floor drain, was unsuitable for the procedure. A floor of pine bark mulch and weeds. The dolphin wobbling to and fro on a makeshift operating table of thin plywood and two spindly saw horses. A full moon, the headlights of a GMC truck and one hand-held carpenter's lamp to illuminate the dolphin's carcass.

"Hose him down," Geraci said, peering at the sand-covered dolphin. He began to examine the carcass. "This is an old animal . . . the teeth ground down," he said prying open the tight jaw. "Roof of the mouth, rough and ulcerated. And tip of the lower jaw. This is typical of what we've been seeing."

Then, pressing his fingers into the dolphin's side, pushing here, poking there, he said again, "This is an old animal."

With a notebook and pen, Geraci began to sketch a model of the dolphin's exterior -- skin abnormally and asymmetrically mottled with shades of gray. "This is most important: All of the epidermis, the outermost layer of the skin -- missing from this entire area . . . . Skin lesions do not appear to penetrate beyond the surface."

He took up a knife and began to cut through the dolphin's inch-thick blubber, marking it with incisions that resembled hastily drawn tic-tac-toe boards. He pulled out thin slices of the dolphin's exterior and dropped them into a container of formaldehyde solution labeled "histology."

With a slow, even stroke of the knife, Geraci removed the dolphin's dorsal fin and held the triangular piece of flesh in his hands, looking first at one side, then at the other while dictating information to his daughter Johanna, who was filling in the medical forms and, when needed, swabbing fluids from the dolphin with long Q-tips and labeling envelope-sized plastic bags of samples.

From the parasites in the pancreas to the otoliths -- fish ear bones -- in the stomach, everything was peered at, bagged and put on ice. The epidermis, the intestines, the back muscle, the adrenal gland, the spleen, the lung nodes, the gums, a section of the vertebrae, the heart and so on -- all pulled out, cut into and pulled apart.

In the intensity of the early morning hours, little time was spared for humor or small talk. There were occasional, wistful jokes about the many missed meals and sleepless days since they arrived in Virginia Beach on Thursday. But for the most part, the 1 1/2-hour operation moved quietly and quickly into the night.