It was a most unusual book party. The novel being celebrated, just published by a major university press, was being given away--free. The author being honored was at home, halfway around the world. And the highlight of the evening was an actual reading from the book itself, 14 pages to an attentive audience of 60 political and publishing types, professors and businessmen.

The occasion was a publication party for "Masseni," a novel by Ivory Coast author Tidiane Dem, winner of the 1981 Pegasus Prize for Literature. The Prize was established by Mobil Corp. in 1977 and is intended to expose American audiences to outstanding works from countries whose literature is rarely translated into English. Winning works are translated into English and published here by Louisiana University Press.

At the center of the party was the poet, playwright, author and actress Ntozake Shange--famous for her Broadway play "for colored girls who have considered suicide/when the rainbow is enuf"--who was chosen to represent Dem at last night's gathering.

"I just want people to know that there are black people all over the world doing amazing, incredible things and not all of them speak English," said Shange.

Dem is 72 and speaks no English, and he was formally awarded the Pegasus Prize in October 1981 in his native Ivory Coast. Shange flew in from Hollywood for yesterday's party/reading at the embassy of the Ivory Coast and a similar reading scheduled for today at New York City's Public Theater. The chatter at the embassy stopped as she whirled in, a blur of color: blue hat, electric orange skirt and rainbow-colored blouse. Although she'd been traveling since 6 a.m., she seemed more energetic than any of the rest of the guests, bouncing from foot to foot, eyes darting as she happily greeted familiar faces. "Everybody should just do whatever they're doing," she said when the party seemed to be bunching up around her, " 'cause I know what I have to do!"

What she had to do was meet and chat with Jessie Amany, hostess of the party and wife of the Ivory Coast's ambassador (the ambassador was in the Ivory Coast); Jonathan Kistler, professor of English at Colgate University and a member of the Advisory Committee for the Pegasus Prize; Leslie Phillabaum, the editor in chief of LSU Press; and Gregory Vittiello, who runs Mobil's part of the Pegasus Prize.

Rep. Peter Peyser (D-N.Y.), sporting a tie with the Great Seal of the United States on it, dipped into the embassy to catch up with some old pals from Colgate, his alma mater, and to lend his support to "Masseni's" publication. "This is one something I can be in complete agreement with Mobil Oil on," Peyser said, laughing. "I can't agree with them on some things, but we agree on this."

Thaddeus Garrett Jr., assistant to Vice President Bush, said his presence demonstrated that the administration is "very much interested in further cementing ties to the countries of Africa."

Shange, who said she was "committed to introducing and sharing African literature with Americans," gave a brisk, dramatic reading of two sections from the book, and said she was "having a great time doing this 'cause I don't have to talk about myself."