SCIENCE SCAN

EXHIBIT

'The Rarest of the Rare: Stories Behind the Treasures at the Harvard Museum of Natural History'

At the National Academy of Sciences, 2100 C St. NW.

Photographer Mark Sloan is known for his work documenting circus and sideshow history, and in this art exhibition, on view through Jan. 7, it shows. "The Rarest of the Rare" includes 20 large, color photographs, all taken in 2003, of such curated curiosities as the southern gastric brooding frog. According to the photo's caption, this extinct Australian amphibian reproduced in a most peculiar way: The mother swallowed as many as 25 fertilized eggs, which then developed in her stomach. During incubation, her digestive system shut down and she ate nothing. After six to seven weeks, she would burp up the fully formed froglets from her mouth and they would hop away.

Sloan, who lives in Charleston, S.C., went behind the scenes at the Harvard museum, which houses 21 million specimens including ants, tusks, meteorites, bird eggs, mollusk shells and gorgeous jaguar, cheetah and zebra hides. "They are the world, distilled," as the National Academy of Sciences puts it.

He photographed the world's biggest egg (the size of 180 chicken eggs) and the morpho butterfly, male on the left side and female on the right side due to a genetic abnormality.

Bring a photo ID to get into the exhibition, which is open Monday-Friday, 9 a.m.-5 p.m.

-- Rachel Saslow