NATIONAL GEOGRAPHIC is going topless again. This time it's mermaids.

"The Mermaid's Tale" has surfaced in Explorers Hall with relics from the seven seas -- from the 1483 Nuremberg Bible, in which a mermaid appears alongside Noah's Ark with her merdogs, to Bette Midler's sequined green tail, worn in the "Clams on the Halfshell Revue."

The mermaid's the traditional province of old salts who are lured by the mystery of the sea, yacht club members who place her on their trophies, and romantics who cry at such movies as "Splash" and "Mr. Peabody and the Mermaid."

The mermaid's found on weathervanes and figureheads. With her long hair (she is never without a comb), she popped up in advertisements for Ayer's Hair Vigor in 1870. And in 1955, Norman Rockwell immortalized her as "The Lobsterman's Catch"; readers of the Saturday Evening Post termed the innocent-looking nereid "indecent." Meanwhile, a gin bottle fashioned into her shape could almost guarantee the misidentification of a manatee.

While the lure and the lore of the mermaid is fascinating enough, this show seems storm-tossed and in need of a heading. One direction would be to speculate as to why the mermaid seems to make an appearance in practically every culture.

She is pictured here on a cup from China; with her meryoung in an Eskimo carving; on a Japanese kite; in an applique from Panama; on an Amish cane from Pennsylvania. She cavorts on 17th-century Delft tiles and hangs from the ceiling in an 18th-century German chandelier. In this last, unlike most mermaids she's fully dressed -- in a gown of the period, with antlers sticking from her hips (cumbersome at best when crashing through waves).

And these treasures are cast adrift in Explorers Hall, in haphazard, not even chronological, fashion.

Another obvious but unanswered question is, why are there so many more mermaids than mermen? In that regard, it can be assumed that there are as many mermaids in the sea as there are sailors too long at sea, as in this Scottish ballad:

She raised herself on her beautiful tail

And gave him her soft, white hand

"I've been long waiting for you, my dear,

Now welcome home from the land."

There are endless mermentions in literature, and the show touches on a number of these. For example, T.S. Eliot wrote, "I have heard the mermaids singing, each to each." If true, this would constitute a problem. They could mean to lure the poet down to the bottom. A mermaid sighting is considered an omen of impending disaster. When mermaids circle the ship, it's a goner.

As recently as 1754 a mermaid was listed with the crayfish in Louis Renard's "Natural History . . . of the Indes," to wit: "A monster resembling a siren . . . lived on land in a tub full of water for four days and seven hours. It uttered, from time to time, little cries like those of a mouse. It would eat nothing . . ."

But Ogden Nash threw cold water on the whole subject when he opined, "Barmaids are diviner than mermaids." THE TALE OF THE MERMAID --

Through October 25 in Explorers Hall, 17th and M NW. Hours are 9 to 5 Monday through Saturday, 10 to 5 Sunday.