PERKINS HARNLY says his guardian angel or his muse looks ''rather like Lillian Russell, only more abstract and, of course, with wings.''

But the paintings that made him famous are less fanciful, careful delineations of life that suggest, as he says, that "the occupants have just been called to the telephone or bathroom leaving their life history behind."

If you look a little harder, you'll see that in his genre paintings are not merely records of nostalgic farm scenes or decaying hotels. They are stage sets for a way of life.

"I was strongly influenced by the theater," he said in an interview recently. "My mother ran a rooming house next door to the theater. When the show would bomb, they'd let down the drop curtain. The curtains in those days were painted with Italianate scenes, poor copies of Parnesi. They were usually of a garden with all sorts of urns and balustrades."

For years, Harnly's paintings have been neglected, though in the '40s his work was exhibited at the Metropolitan Museum of Art and published in Vogue and Americana magazines. He claims to have originated the small sketches which enliven the text of The New Yorker magazine.

Now Harnly's work is being bought back by the National Museum of American Art. Twenty-nine American interior scenes by Harnly are on display there through Feb. 15, together with a fine monogram by Linda Ross Hartigan with Virginia Mecklenburg. This show may well spark a great Harnly revival.

The earlier paintings were done for the Federal Art Project's Index of American Design, now at the National Gallery of Art. A later group was commissioned by Albert Lewin and donated to the Index collection.

Harnly is 81. He came to Washington recently for the opening of his show.

"I live in a single room with tall mirrors in the Culver City (Calif.) Hotel. I get up at dawn and go over to the cafeteria. I'm the counterman. I'm not supposed to be there until 8, but I get lonesome." In the afternoon, he paints, with the light from his windows overlooking the sea. He hadn't painted for sometime, but recently he met some young people at a movie revival house who encouraged him and bought his work. ------------------------- ------ ---met some young people at a movie revival house who encouraged him and bought his work.

Harnly has spent much of his life working at odd jobs, principally as a counterman in cafeterias. During the depression, when the government commissioned a record of American design and handcrafts, he worked for the Index, drawing mostly Victorian interiors. He designed stockings for Gypsy Rose Lee (lace with a flame design going up her thighs), and the set for "The Picture of Dorien Gray."

"But I was part of a strike at the movie studio and I was blackballed," he said. "So for 20 years I didn't paint." In 1967, an old friend sent him $500 and told him to paint again. "So I did, and at the gallery show, I sold 15 paintings for $350-$550 in one afternoon. I'd never seen so much money. I took it and went to Europe. Soon as I got off the plane, I went to the graveyard where Sarah Bernhardt is buried. I always go there. I love painting graveyards. Some of them are so funny, like the one made in bronze of a bed, complete with a man and wife with a sheet over them. The man is writing something. I have my own funeral urn in my room. I'm going to be cremeted. It's a big urn, I could have somebody in with me. Several have said they'd join me."

In the NMAA show is his painting of a monument display room of 1888 (drawn in 1947), a marvel of RIP devices from angels to urns, all set in a gay building of glass arches.

"When I was a young man I was a hotel elevator operator. The elevator was broken when Bernhardt came in that night from the theater. She was close to 90, with only one leg. She went about in a sedan chair. Another man and I had to carry her chair up four flights of stairs. Everytime we'd pass a mirror, she'd preen."

Images of Bernhardt and Lillian Russell keep appearing in his paintings. "You can tell by my paintings exactly how I was feeling. That's why I don't keep any of them on my walls. I can't stand them when I'm through. They remind me of too much emotion. Whether I was happy, or sad or sexually tormented."

Harnly said that when he painted it was like "pulling a cork and letting the champagne fizz all over."

Of his later paintings one of the best (also in the show) is a cocktail lounge, painted in 1946, showing soft, art deco type stylized sofas and chairs, a jukebox, a pinball and gumball machines, signs, mirrors and other decorations left over from the 1940s. A poster on the wall shows a nude labeled "Atom Bomb," and another called "Miss 1946 1/2."

The other paintings in the show, mostly gouache on paper, are equally varied. A factory scene ,also in 1946, is of a Japan lacquer dipping vat. All the objects, from the vat to the solvent tank to the hose and the warning signs on the floor are shown in exquisite detail, almost super sharp.