One boy genius bought another boy genius' toy sled today for $55,000.

Steven Spielberg, 34, the director of "Jaws," "Raiders of the Lost Ark" and his newest picture, "E.T.," today bid for and won at auction the little red sled whose innocence was at the core of the then-26-year-old Orson Welles' "Citizen Kane," one of America's greatest sound pictures.

Bidding over the phone from California, Spielberg allowed Sotheby Parke Bernet's Jane Wyeth to commit the $55,000 for Rosebud, as the sled is known, thus frustrating and finishing the next closest bidder, Texas tycoon Lucian Flourney, who put his bidding paddle down at $50,000. Spectators in the gallery burst into yells and applause at the successful purchase.

"One thing I want to say," Spielberg said later from his production offices in Burbank, Calif., "is that this is a symbolic medallion of quality in movies. When you look at Rosebud, you don't think of fast dollars, fast sequels and remakes. This to me says that movies of my generation had better be good."

Spielberg said he first heard of the sled's availability when he spotted an item in American Film magazine. The sled had been owned by John Hall, RKO's chief archivist, who had bought it from a studio watchman. The watchman had found it in a trash heap outside the prop vault in the old RKO studios in Hollywood.

Spielberg's friend, George Lucas, the producer on "Raiders," and the maker of the "Star Wars" and "The Empire Strikes Back," also had a yen for the sled. But he agreed to let Spielberg do the bidding and take possession in the auction that could conceivably have set new records for film memorabilia.

"I was ready to go higher, I could have gone to a million," said second-place finisher Flournoy, "but I didn't think the item was worth it ultimately." Sotheby's Wyeth, however, said Spielberg was also ready to pursue it aggressively and had not put a ceiling on how much he would bid.

The 34-inch-long sled is made of red balsa wood with off-white runners and a green-leafed rosebud with a white blossom stenciled on its surface. It was one of three sleds made for "Citizen Kane." One was burned as part of the filming for the picture's ending; another, the sled that the young Charles Foster Kane rode on down midwestern snowdrifts in the movie, belongs to Tom Mankiewicz, the son of Welles' coscreenwriter Herman J. Mankiewicz; the third sat in Sotheby's 71st Street auction gallery today, desired by several aggressive bidders.

Spielberg, who first saw the movie when he was 18, said, " 'Citizen Kane' is to me the American style. In its exuberance, in its innovation, in its use of lighting, time forwarding, film editing, makeup, docudramatic performance, it was the milestone movie of the last two generations. It's the most audacious, purely American movie we have."

The Rosebud bidding was the last event in a full day of a collectibles auctioned at Sotheby's. Jukeboxes, a great deal of Beatles memorabilia--including John Lennon's erotic lithograph drawing "Bag One" (which went unsold with its price floor at $20,000)--and Dan Aykroyd's conehead from "Saturday Night Live" (which went for $275) had all gone up for auction, pulling in light bids and in most cases less money than the owners expected.

Lot 265, Rosebud, was estimated in the catalogue to go for between $15,000 and $20,000. Mrs. Boone Brackett of Chicago had come to New York with orders from her husband to exceed the ceiling no matter what it was. Flournoy, from Alice, Tex., had seen the movie 41 years ago when it was released and said it had never left his mind. Other bidders sat around the room waiting for the lot with vague aspirations of getting a classic piece of Americana at a bargain. That was not, however, the prevailing mood of the day.

"I thought we'd be going high," said Wyeth. "I told Steven to expect to go to 60. When it started going up, I knew he'd stay with it no matter what. He wanted it.

"When he got it, he said, 'I'm thrilled. It's the most exciting thing to have happened to me in several weeks.' "

Little Rosebud was not the only item Spielberg picked up this afternoon. He bought seven celluloid drawings from Walt Disney Studios which were created during the '30s, including the terrifying shot of the evil queen in "Snow White" presenting a casket in which to put Snow White's heart, and a celluloid from "Dumbo" to break your heart, with the elephant peeking shyly around from behind his mother. Lucas also bought several Disney celluloids after allowing Spielberg to bid on the sled without pitting any of the resources from his own vast movie fortune against him.

Spielberg, who has never met Orson Welles but who "would jump through the air at the chance to," said he had been inspired by the director's work in "Citizen Kane," "Touch of Evil" and "The Magnificent Ambersons." He said the last shot in "Raiders of the Lost Ark," which showed thousands of crates, one in which the ark was stored, had indeed been a tribute to a similar, penultimate sequence in "Citizen Kane." "It was George Lucas' idea," he said, "but it wasn't hard to guess where he got it. 'I know where that's from,' I told him when I heard it.

"I ran into 'Citizen Kane' late in life, at Long Beach State College when I was 18. It made a big impression on me. I don't think anybody would ever try and remake it. There isn't an American stylist capable of the daring, the audacity, the foresight to ever violate the air space of Orson Welles--and Orson Welles deserves a lot of air space."

Spielberg had independent sourcing done to verify the sled's authenticity before he bid on it. Hall, RKO's head archivist, identified it without challenge as the article created for "Kane." When that was done, Spielberg, set on purchasing it, arranged the telephonic bid with Wyeth, who flinched not for a moment as the price shot up to near the equal of the salary of a United States senator. "It was the most exciting bid I've ever worked on," she told Spielberg after the deal was set. "Do you want it sent to your home or to the office?"

Spielberg, whose picture "E.T.," the story of a little lost space boy abandoned on Earth, opens Friday, said he doesn't expect to put little E.T. up for auction at Sotheby's in 50 years or even 100, "because I'll have that at my house." He was asked whether E.T. was there now and he giggled. "Yes . . . he is," Spielberg said, which meant, perhaps, that E.T. would be getting a sled this winter for Christmas.