A ribbon of black hair reaches down to his nose, separating the cold eyes like the nosepiece of a medieval helmet. Regal, cruel, master of his people, he stares out of the canvas at an alien world, a question in his face as though he sensed a future that would have no room for him.

This is Buffalo Hump, chief of the Blackfoot Blood Tribe, painted in 1832 by George Catlin, who had him pose in a room while his braves and his enemies looked on. Catlin called him Buffalo Bull's Back Fat and entered the portrait in the Paris Salon of 1846. That was typical of Catlin, who loved to say he wasn't an artist at all but merely a recorder of history, thus protecting himself against critics.

About 100 of Catlin's Indian paintings are at the National Museum of American Art (known to most as the National Collection of Fine Arts) through Sept. 13. The museum owns more than anyone, 445 of them, the National Gallery another 351. Like old photographs, their poignance tugs at us: Here is the lost landscape of the past, and we can see its vanished skies and hear the neighs of longforgotten horses and smell of wood smoke rising from the tepees, and almost, almost step right into it.

Catlin's furious drive to capture all this, to get it down before it disappeared, gives his work even more appeal than photos, in a way. The very sketchiness of his hasty crowd scenes which the faces barely indicated, the brown masses of buffaloes, the dusty excitement of a game being played by women whose streaming black hair looks like a swirl of pollywogs, all these impressions have the immediacy of a moment remembered.

Sometimes he painted abstract cloudscapes and mountain backgrounds in his studio so he could add the figures quickly when he reached the scene. There is a roomful of these curious empty vistas waiting for something to happen to them. Close by are paintings that seem to have started with the ready-made backgrounds: They don't quite match, somehow. But other landscapes have the evocative swell and spread and distance of a Grand Wood counterpane.

There are many portraits, notably a full figure of Buffalo Bull, a Pawnee warrior, with bow in hand and a buffalo head painted on his face for a fearsome appearance. The sure, quick lines of the original sketch can be seen here in the hands and arms. Clearly, Catlin filled in the details of face and decorations later. Some portraits bristle with character, others seem rather perfunctory.

It is in the scenes of Indian life that Catlin's method works best. The hunts, the games, the dances, the grisly Okipa ceremony of the Mandans, the night ceremonies -- all of them shimmer with vitality. One scene shows Indians fleeing a prairie fire that blackens the sky with its vast, stylized rolling clouds. The sense of panic is almost palpable. In a buffalo hunt, an unhorsed Indian, trapped in the middle of a plunging herd, is actually walking to safety on their backs. Buffaloes being pursued in waist-deep snow struggle to escape the hunters in nightmare slow-motion.

One of the strongest images is a close-up of a dying buffalo, legs wobbling, blood streaming from mouth and nostrils. Catlin reports that he wounded the animal near the Yellowstone River and rode around it, prodding and sketching it until it collapsed. He has captured here the massiveness of the beast, its bafflement, its implacable bravery. The famous painting of a bear's face and claws is also in the show.

Catlin, who died in 1872, at age 76, liked to say he was self-taught, but his work indicates classical training. One party of braves is spread out in an even line, striking attitudes worthy of a Greek frieze. Other scense betray subtleties, color harmonies, dynamic balances that one doubts were learned by trial and error. He traveled in Indian country for six years in the 1830s by horse, canoe and steamboat, visiting 48 tribes, sketching and taking notes in his journal, returning to his studio to complete the work. Some paintings were elaborately finished; others were left hardly more than drawings.

Perhaps it is that combination of haste and reflection, that urgent need to preserve the moment and that wish for artistic recognition, which gives this show its wonderful energy.