Mr. and Mrs. Edward W. Lane Jr. of Jacksonville, Fla. have the pleasure of announcing the engagement of their daughter, Helen Palmer Lane to Christopher Stump Middendorf, son of Mr. and Mrs. W. Kennedy B. Middendorf of Syosset, Long Island.

Miss Lane's father is chairman of the board of the Atlantic Bancorporation. She is the granddaughter of Mr. and Mrs. Charles H. Murchison of Jacksonville, former residents of this city; Mr. Murchison is a practicing lawyer and partner of Ulmer, Murchison. Her paternal grandparents are the late Mr. and Mrs. Edward W. Lane; Mr. Lane was founder and first president and chairman of the board of the Atlantic National Bank of Jacksonville. Mr. Middendorf's father is President of the United Mutual Savings Bank of New York. His grandparents are the late Mr. and Mrs. Harrison Reynolds of Boston, Mass., the late Mrs. Boone Middendorf of Baltimore, and the late Harry S. Middendorf of Reisterstown, Md.

The prospective bride, an alumna of the Bartram School, Jacksonville, received a BA in philosophy from Sweet Briar College in 1973. She has studied at the University of Caen in France and spent a year at Washington and Lee University on an exchange program with Sweet Briar, and later went on to take a master's degree in art history from Tulane University.

A 1970 alumnus of the Middlesex School in New England, Mr. Middendorf is a 1974 cum laude graduate of Harvard University where he was a member of the Fly Club, captain of the Harvard Sailing Team, and elected to the Collegiate All American Sailing Team in 1974. Mr. Middendorf founded the Middendorf Gallery in 1974 and is now co-owner along with Miss Lane of the Middendorf/Lane Gallery in this city, specialists in twentieth century American art.

The evening wedding will take place on August 26 at the home of the future bride's parents to be followed by a reception at Timuquana Country Club in Jacksonville.