A federal jury in Boston declared on Friday afternoon the Wamponoag Indians of Mashpee were not a tribe on certain legally crucial dates, a decision which may hinder the Indians' attempt to claim a large land area in Mashpee, Mass.

The all-white jury of eight men and four women said Friday the Wamponoags were not a tribe in August 1976 when they filed the suit, nor in 1790, the date of a federal law that forms the basis for the land claim went into effect, nor in 1869 or 1870, when the Indian district of Mashpee was incorporated as a town.

However, the jury added the Wamponoags were a tribe in 1832 and 1842.

Judge Walter F. Skinner did not dismiss the Indians' lawsuit, but gave the Indians' attorney until January 20 to show a reason why he should not dismiss the case.

40 Days, 40 Nights

The decision brings to a close over 40 days of sessions to determine whether or not the Wamponoags of Mashpee are a tribe, the first step in trying their suit, in which they claim over 11,000 acres in Mashpee valued at $30 million.

The Wamponoags based their suit on the Indian Non-Intercourse Act of 1790, which prohibited the transfer of Indian lands without the consent of the federal government. When the Massachusetts legislature incorporated Mashpee as a town in 1870, the Indians claim it violated this law and so the land in Mashpee belongs to them.,

The lawyers for the Wamponoags and for the town disagreed yesterday whether the jury's decision constituted a defeat for the Indians.

Absurd

Alan van Gestel, one of the lawyers for the town, said yesterday, "It's a clear-cut victory--if there isn't a tribe in 1976, then there's no plaintiff, and no case."

But James D. St. Clair, the chief defense counsel, could not be reached yesterday for comment.

Lawrence D. Shubow '44 attorney for the Indians, said yesterday the decision was "logically absurd--how can you say there is a tribe in 1834 and not in 1869?" He added he believes the decision to be so contradictory that the judge may have to order a new trial.

Thomas N. Tureen, attorney for the Indians, said Saturday the jury returned "an impossible set of answers not supported by the evidence."

He said the defense lawyers offered the jury a false definition of a tribe, which may have confused the jury. St. Clair emphasized the assimilation of the Mashpee Indians in his arguments but Tureen said "You don't stop being an Indian because you're culturally assimilated."

Ellsworth Oakley, supreme sachem of the Mashpees, said Saturday, "How can a white majority decide on whether we are a tribe? We know who we are."

George Benway, one of the selectmen of Mashpee, said last month the trial has caused the "economic strangulation of the town and the heightening of personal disagreements." He cited sharp drops in tax revenue and land values because the lawsuit has placed all land title in question.

Psychological, Not Ecological

Shubow said he believed the outcome of the trial will have a "psychological, not a precedental effect" on other Indian lawsuits in Rhode Island and Martha's Vineyard, as well as on a separate attempt by the Mashpee Wamponoags to gain federal regulation of their tribal status by the federal Bureau of Indian Affairs.

Tureen, the attorney for the Gay Head Wamponoags, said he could not predict the effect of the Mashpee decision on the Martha's Vineyard case in which the Wamponoags of Gay Head are claiming 200 acres of land in Gay Head. He added the difference between the two cases is that "the people have a disposition to resolve the matter."

Albert M. Sacks, dean of the Law School, is acting as mediator between the Indians and the town of Gay Head. He was not available yesterday for comment