In a three-way partnership that will protect the last key piece of undeveloped land at one of the oldest wildlife sanctuaries on the Vineyard, the Martha's Vineyard Land Bank, the Massachusetts Audubon Society and the Felix Neck Wildlife Trust announced yesterday that they will buy 34 acres from Lucia Moffet for $2.55 million.

The Moffet property runs along the entire length of the entrance road to the Felix Neck Wildlife Sanctuary on the eastern side.

"It's the last piece; this is the finale," declared Augustus Ben David 3rd, the venerable executive director of the sanctuary.

Named for the last Native American who lived on the neck of land fronting Sengekontacket Pond, Felix Neck includes 303 acres off the Edgartown-Vineyard Haven Road and two miles of shorefront along the pristine pond. Founded 33 years ago with an unambiguous mission of environmental education for children, the wildlife sanctuary has been notable for its constancy over the last three decades amid a rapidly changing landscape and culture on the Vineyard.

The sanctuary was created through a gift of land from the late George Moffet in 1968.

"George Moffet made this possible and so this is a completion of his legacy," said Massachusetts Audubon Society president Laura Johnson yesterday.

According to the terms of the sale, Felix Neck and the Audubon Society must raise a minimum of $500,000 to contribute to the purchase price. The land bank will contribute the balance of the purchase price, unless the other two groups can raise more than $500,000. A closing is planned for January.

Mr. Ben David and Ms. Johnson said the trust and the society have already received an anonymous foundation pledge of $100,000 to put toward the purchase, leaving $400,000 to raise. A capital campaign will be launched to raise the needed funds.

The 34-acre property is vacant except for Lucia Moffet's house, which she will keep. A conservation restriction will be placed on nine acres surrounding the house; the remainder of the land (about 25 acres) will be owned by the land bank.

The Audubon Society and the trust will donate trail easements to the land bank, and trails are now planned through the sanctuary along Major's Cove, and to The Boulevard and the Edgartown-Vineyard Haven Road. The land bank is a public conservation agency that buys open space using funds from a two per cent transfer fee on most real estate transactions.

"This is absolutely the most perfect example of cooperation that you could imagine," said Mr. Ben David, who has been executive director at Felix Neck since 1969.

"From public to private, the land bank has been great with all of this," he said. He also credited Alan Gowell, a member of the sanctuary committee and chairman of the trust, who worked closely with Lucia Moffet on the complicated transaction.

Talks aimed at acquiring the Lucia Moffet property have been under way for many years.

Ms. Johnson and Mr. Ben David said the talks became active again about a year ago, and the option was signed yesterday.

"The land bank is cleaning up items on its 1986 to-do list," said land bank executive director James Lengyel yesterday. The land bank was founded in 1986; Mr. Lengyel said acquisition of the Moffet property has been on the priority list from the start.

"It says a couple of things - it says that truly this land is valuable and worthy, and it also says that when the land bank sets a goal, it sticks to its commitments," Mr. Lengyel said.

Mr. Moffet, an avid sailor, photographer and conservationist, first began coming to the Vineyard in 1960. In 1962 he bought 200 acres of the former Aroz Smith farm from Walter Smith Jr.

"This was historic Felix Neck, farmed since early days, and before that the home of Indians for the last of whom it was named," wrote the late Henry Beetle Hough when Mr. Moffet died in 1978.

In 1968 Mr. Moffet gave most of his land to Felix Neck. The beginnings of Felix Neck were rooted in the Martha's Vineyard Natural History Society, a group founded by the late Anne Hale. In 1969 Ms. Hale's natural history society launched Fern and Feather, a summer day camp for children dedicated to environmental education. Mr. Moffet was an early devotee of the camp.

Felix Neck became a Massachusetts Audubon Society property in 1982. The Felix Neck Wildlife Trust still owns a large portion of the property fronting Major's Cove and a smaller meadow fronting Sengekontacket Pond. The meadow is the site of "Steelhenge," a metal sculpture commissioned by Mr. Moffet after he traveled to England one year and was inspired by Stonehenge. The sculpture was created by Vineyard metal sculptor Travis Tuck.

The Felix Neck Sanctuary includes nature trails and it sponsors numerous natural history programs for children and adults. Mr. Ben David supervises a rehabilitation center for injured birds on the property, and the Fern and Feather camp continues today. Mr. Ben David has two grandchildren who are attending the camp this summer.

"Felix Neck is every bit as much about people as it is about conserving wildlife - and I go back to George Moffet and the mandate I had from him, which was to keep the place happy," Mr. Ben David said.

"Felix Neck is the perfect Audubon Society property, because the mission of the society is to connect people with nature and help them learn about nature so they will take action to protect nature," Ms. Johnson said.

Mr. Ben David said conservation of the Lucia Moffet land is crucial to the sanctuary, in part because of its location along the entrance road to the sanctuary, but also because it is part of a whole that has remained intact for literally thousands of years.

"You drive down that road that hasn't changed since Native American time - if that had changed, well, quite frankly I don't think I would have survived it. Just think about how many thousands of kids have come down that road and had the benefit of Felix Neck," he said.

"This protects the entire edge of the entrance road and when you think about that being safe and secure - well, it means that I can finally sleep at night."

Mr. Ben David, whose work as a naturalist spans his whole life, acknowledged that Felix Neck has not wavered in its mission for 33 years, and he said bluntly that this is the strength of the sanctuary. "I learned a long time ago that you don't diversify to the point where you become ineffective," he said.

"Felix Neck is in Edgartown but it really is a Vineyard entity. We are thankful to the Smith family and we are thankful to George Moffet, and now to Lucia Moffet. Just think of the generations of people that have enjoyed that land because George Moffet gave it," Mr. Ben David concluded.