TOf all the legendary worlds of antiquity, only the "lost" land of Atlantis has refused to fade away. It is forever being rediscovered -- and then lost again.

Its latest ephemeral appearance was a few hundred kilometers off the Portuguese coast in the direction of Maderia, at a depth of some 3,000 meters.

There, a Soviet oceanographic team look a couple of sea-bottom photographs which the team's leader, A. Aksenov, was quoted as saying showed "vestiges of walls and stairways." He also was quoted as suggesting "it's possible that it's part of Atlantis, maybe not the whole thing, but a part."

The Soviet oceanographers had photographed the Ampere Seamount. The intriguing "ruins" showed up in a couple of the film's frames.

"One of them shows eight stones -- four square ones and four rounded one, in a line about three and a half or four feet long," Aksenov was quoted as saying adding that, "Specialists who've looked at it say it's a typical wall from antiquity. The second photo shows three equally spaced stones at the edge, and it appears to be part of a staircase."

While Western oceanographers were skeptical, the reports raised some public interest last spring. But unhappily for Atlantis fanciers, Aksenov now says the press accounts were a "misunderstanding," according to the journal Nature.

The photos merely show natural formations of Mount Ampere. It would appear that Aksenov, speculating only half-seriously as scientists often do, was taken too much at his word and another vision of Atlantis has faded.

It ever was thus with this fabled land. Even the quite serious hypothesis that linked Atlantis to the Aegean island of Thera now looks shaky. The most violent volcanic explosion know occured there 3,500 years ago.

Some oceanographers and archaeologists have suggested that this was responsible for the pricipitous, and mysterious, decline of Minoan civilization. The ash fall and accompanying tsunami ("tidal wave") could have affected surrounding islands including Crete, the Minoan center. Atlantis would then be indentified with Thera itself. All trace of it would have been wiped out by the eruption.

However, there is a gap of 50 years between the eruption and the Minoan decline. This presents no problem if the eruption really were a series of events over a span of decades. But, as noted last year at an international conference on the subject, it looks as through there was only a single volcanic event.

The identification of Atlantis with Thera doesn't seem quite so plausible now, although, as D.H.Ttarling of Britains's University of Newcastle-upon-Tyne noted: "It would be surprising. . . if such a major series of tectonic events should not be directly related to the otherwise puzzling, rapid decline of the Minoan civilization. . ."