Though most of us are moping, or melting in the heat, the Henri Gallery's Henri has lost none of her ebullience. Her current summer group show has a jauntiness that dissipates the dullness of these dog days. There are 18 artists in it. Though the objects they are showing could hardly be more varied, they still manage to present weird juxtapositions and unexpected rhymes.

Of these, by far the oddest is the subject matter shared by Philadelphia's Italo Scanga and Washington's Tom Nakashima. It is as if both have heard the song of precisely the same muse.

Scanga's 1981 construction is called "Egyptian Woman With Fish and Singing Heads," and that pretty well describes it. It might be a description, too, of the 1985 Nakashima painting on display nearby.

An imposing, alien woman, large and nude and stiff, appears in both objects. So -- floating at the left of both -- does a giant fish. Scanga draws in charcoal, and often scribbles as he draws, but though his surfaces feel casual, unworried, his art is strangely dark. His construction, with its pedestal, its glass vase and its painted frame, could decorate a nightmare. The two heads he has drawn don't merely sing, they scream.

Nakashima's boldly brushed painting -- it's called "Trouble in Paradise" -- is comparably disturbing. His painted nude, like Scanga's, is threatened inexplicably by a monster of a fish. The flag glimpsed in the background of Nakashima's picture is part patriotic banner and part darkened shroud. Yet something almost joyous bubbles in both visions. Even as they frighten, both works entertain. In the free exuberance of Nakashima's brushstrokes -- as in Scanga's charcoal drawing -- is something close to play.

The Henri exhibition includes other works of merit. One of the most impressive is "Ganesa," a large Abstract Expressionist portrait by Washington's Bill Roseberry of the Indian elephant god. Ganesa's ears are flapping, his belly is full-fed. Roseberry's brushwork appears wild, but his figure dances gracefully. How nicely his trunk sways.

Also worth noting are Don Grant's interiors, with their ectoplasmic ghosts, Kathleen Montgomery's minimalist abstractions and the gold-leafed icons of Randy Walz. Dennis Lick's constructions, with their brightly colored rectangles and cones, would be more impressive were they not so deep in debt to the example of Frank Stella. Henri's group show closes Sept. 2. Zinnia's 'Garden' at the Touchstone

The Washington artist who calls herself Zinnia is showing her "Aquarian Garden" at the Touchstone Gallery, 2130 P St. NW. Her complicated installation -- with its collaged photographs and folding screens, its leaves and bugs and lily ponds -- ought to be an antidote to August's enervating heat. But it isn't. The heat wins.

Her garden, though designed to leave the viewer "refreshed, rejuvenated, optimistic," irritates instead. Her trees aren't green, they're red. Her foliage is littered with bits of brick and sliced-up cars. Her cacti of green foam are all a little creepy. Her plastic snakes and plastic frogs, and her lily pond of crumpled crepe paper and cellophane, suggest ill-told, failed jokes. Gardens should be cool and green. Zinnia's is arid. It will remain on view through Sept. 8. Baobabs and Buck Rogers

E.H. Sorrells-Adewale and Grace Gorlitz are sharing a two-person exhibition at the Midtown Gallery, 1630 Connecticut Ave. NW. One cannot help compare their art, and the comparison is telling. Both of them employ assortments of found objects in their wall-hung constructions. Both like dapplings of paint and well-tuned pastel colors. And yet, at least in spirit, there is little their art shares.

Gorlitz evokes robots, space debris, star warriors -- the sort of entertaining glitz one finds in science fiction films. Her pieces, with their steel springs and wheels, light switches and wing nuts, suggest the fun and silliness of mad geniuses' machines. Sorrells-Adewale prefers to build collages of cowrie shells and scarabs, miniature pyramids and wooden twigs, toy elephants and feathers. He uses bits of paper bags and small carved wooden wings to call to mind the windblown sands and wheeling birds of some far-off sun-baked desert.

Gorlitz's titles -- "Star Wars," "Space Debris," "FTD Robot Bouquet" -- suggest Buck Rogers comic books. Those preferred by Sorrells-Adewale -- "Journey of a Soul," "A Thought Concerning a Warrior," "Ask Baobab" -- conjure up instead a land, perhaps North African, of caravans and veils, shadows, myths and dreams. He is an associate professor at Howard University. The exhibit closes Sept 5.