Laurence Gouverneur Hoes, 78, a great-great-grandson of President James Monroe and a founder of the James Monroe Museum and Memorial Library in Fredericksburg, Va., died Saturday in Berlin, Germany. He had a heart aliment.

Mr. Hoes, a former investment banker here helped found the museum in 1928 on the site of President Monroe's old law office in Fredericksburg. He had served as president of the board of trustees of the James Monroe memorial Foundation and was a member of the board of the James Monroe Library. In addition, he traveled around the country lecturing on the subject of the Monroe Doctrine.

Mr. Hoes was born in Boston, but moved to Washington with his mother at an early age. After graduating from St. Albans School for Boys he enlisted in the Army and served in France during World War I.

First marriage to Ingrid Westesson Hoes of Washington, ended in divorce. In 1969, he married the former Camilla Goerlich of West Berlin and made his home in West Berlin.

He was a member of the Sons of the Revolution, the Sons of the American Revolution, the Virginia Historical Society, the Columbia Historical Society and the Northern Neck of Virginia Historical Society. He also was a chevalier of the French Legion of honor.

In addition to his second wife, he is survived by a son by his first marriage. Monroe Randall Hoes, of Wayland, Mass., and two grandchildren.