Trapped between the jungle and the metropolis; Maira, by Darcy Ribeiro. Translated by E. A. Goodland and Thomase Colchie. New York: Vintage/Aventura. 304 pp. $7.95. Paperback.
Isaias, a young Amazon Indian, has been converted to Christianity. He intends to become a priest in Rome but changes his mind just before his ordination. When he returns to his people, the Mairun, he reverts to his Indian name Ava. ''Maira'' is largely his story, told in flashback, of his alienation and his encounter with the white woman Alma. The story begins with the discovery of the corpses of Alma and her fetal twins on a beach up the River Iparana, deep in Indian territory. The deaths mystify the police; the Indians begin to fear white retaliation. Races and cultures seem headed for a tragic confrontation.
Inevitably, there is a familiar return of the native quality to ''Maira,'' as Ava/Isaias experiences what anthropologists describe as cultural alienation. The theme pervades too much of third-world literature. While in the metropolis, Isaias cannot forget the Mairun; while in the Amazon, Ava is too cosmopolitan to feel wholly at ease again with his tribe. Clearly he has assimilated too much of European culture to become retribalized. We feel immediately that his relationship to Alma is designed to set him up for tragic consequences.
''Maira'' strives for a cathartic effect, and Ribeiro offers a fascinating glimpse inside a South American Indian tribe. In many respects Isaias is more than a modern exotic. His Indian-ness is allegorical: He reflects the loss of primitive innocence in us all. This is not an easy kind of fiction to create, but Ribeiro, a renowned anthropologist, makes a largely successful effort.