ENEVA, May 5 ó To Vladimir Nabokov's favorite translator and only son, the thought of selling the books his father so intricately annotated with fantasy butterflies and personal asides was distressing, but it had to be done. That son, Dmitri Nabokov, who turns 70 on Monday, felt his own death approaching, he said in an interview, and he wanted to leave no loose ends.

So he decided to sell his father's memorabilia collection, which included an elaborate sketch on the flyleaf of a book showing the imaginary "Verina raduga Nab.," with its dappled wings of violet and blue, blood-orange glimmers and iridescent greens. It was auctioned in Geneva on Wednesday.

"Of course it tugs at the heartstrings to let go of these lovely butterflies," Dmitri Nabokov said at his home in Montreux, Switzerland. "The little, simple ones are so touching. But I would rather do a thing like this lucidly," he said. "Having seen death close up on three occasions, it's frightening to think you might leave such precious loose ends."

Dmitri has no direct heirs, so when his parents were still alive, it was decided that the books would be auctioned before his death. The collection, a few items excepted, sold on Wednesday for nearly $750,000, a lower price than anticipated. Various private collections, most from France and Switzerland, bought parts of the collection, which will now be scattered to the breeze.

Vladimir Nabokov died near Montreux in 1977. Dmitri Nabokov's library consisted of a wide array of his father's novels, short stories, poems and translations, as well as a small set of critical studies. Dedicated for the most part to Dmitri and his mother, VÈra, the books were often autographed and annotated. Many are deftly adorned with butterflies, drawn in ink or color pencils on the first page of every work.

The first major series of Vladimir Nabokov archives and manuscripts was acquired in 1991 by the Berg Collection of the New York Public Library. This second series, and perhaps the last, constitutes more than 100 volumes and 30 titles, a remarkable medley of Russian and American literature.

"I am an American author, born in Russia, educated in England, where I studied French texts," Nabokov once noted. After publishing eight novels in Russian, he began a flamboyant writing career in English with "The Real Life of Sebastian Knight," written in 1941 when he was 42. "Lolita" came 14 years later, and Nabokov called it "the record of my love affair with the English language."

Others read "Lolita" as a record of a more scandalous sort of affair, which brought that novel and its author international notoriety, along with immense critical acclaim.

From then on Nabokov endured ceaseless scrutiny. Who was this man who could write with such heart-rending poignancy about the ever-crafty charms of a nymphet?

In this light the books of Dmitri's library each offer a particular insight into the private Vladimir Nabokov, whose psyche was a far cry from the myriad personas of his characters. Nabokov was deeply in love with his wife, who died in 1991, and was a tender and attentive father. In a collection of short stories that sold on Wednesday, Nabokov wrote: "For VÈra. Adorata adorata. From V. Jan. 5, 1970. Montreux." In "Despair" he jotted for his Mitioucha, the diminutive for Dmitri: "For Dmitri. From translator to translator. With love. Vladimir Nabokov. Papa. Montreux. 1966."

The collection also presents ample handwritten notes. On opening pages or in the margins Nabokov points out plentiful misprints and errata, revealing unusual concern for minute revisions and retranslations. The first page of an early edition of "Ada, or Ardor" reads, among a web of other notes: "p. 257 last line should be `he was pregnant' (not `she'!)." Occasionally other hands, namely VÈra's and Dmitri's, make cameo appearances.

Perhaps the most original piece is a book of expenses (1949-1952), which provides an endearingly scrupulous shopping list: "New Yorker $00.40, Coca-Cola $00.10, movies $1.80, groceries $4.80, April rent $125."

Then there are the fantastical butterflies, each selling for anywhere from $1,500 to $25,000. Those intended for VÈra are perhaps the most resplendent and sold for the highest prices.

They have variegated colors, delicate artistry and fanciful names. Only on these pages appear the blue "Colias verae" or the dark "Maculinea aurora Nab."

Aside from his writing, Nabokov was a world-class lepidopterist who became the curator of the butterfly collection at the Museum of Comparative Zoology at Harvard in the late 1940's. He discovered numerous real species, which bear his name, and created a revolutionary taxonomy still used today.

Nature, Nabokov once said, conjures up the same sort of mystification and magical spell as art. And like so many diaphanous signposts of Nabokov's celebrated "other worlds," these "pretty insects" inhabit his prose: "A butterfly in the Park, an orchid in a shop window, would revive everything with a dazzling inward shock of despair," utters Van Veen in "Ada"

Dmitri Nabokov observed that there is a tiny consolation to selling these books now. "Today it is possible to scan and preserve superb copies of all the graphic materials," he explained. As for the near future, he said that the earnings from the sale have not been earmarked for a specific project. In time they will probably contribute to the PEN Nabokov literary award, a literary foundation and the Nabokov Museum in St. Petersburg, which the Russian government has threatened to close. Dmitri said he harbored the hope of buying the museum, his family's former home, which is estimated to be worth about $18 million without its contents.

Jacques Tajan, a well-known auctioneer, presided over the sale. "People who buy these books need to pay a significant amount of money," he said. "Only then will they conserve them adequately." Mr. Tajan emphasized the sentimental value of the auction: "It is bliss for me to do this. It will be a terrific memory in my career."

No matter, Nabokov's butterflies were separated. And the distant echo of his "Speak, Memory" seemed to be touching them with its fragile grace: "To love with all one's soul and leave the rest to fate."