May Philipps Train, 91, the author of three books on genealogy, died of cancer Friday at the Bethesda Naval Medical Center. She lived in Washington.

She was the widow of Rear Adm. Harold C. Train and the mother of Adm. Harry D. Train II, who is commander of the Atlantic Fleet.

Mrs. Train was born in Manitowoc County, Wis. She grew up in Kaukauna, Wis. After her marriage to Adm. Train in 1915, she traveled extensively with him to the Orient and to disarmament conferences in Geneva, Switzerland and London.

In 1943, she sponsored the submarine U.S.S. Lionfish at a ceremony in Philadelphia. Later she and her husband, who was commander-in-chief of the Military Order of World Wars, lived in Annapolis. She moved to Washington after his death in 1968. Mrs. Train published three genealogical books, "Samuel Bullen and Some of His Descendants," "The Train Family" and "Tracing Backward."

She was a member of the Sponsor Society of the U.S. Navy and a former member of the Society of Arts and Letters in Washington.

In addition to her son, who is stationed in Norfolk, she is survived by two daughters, Cecil Train Wilson, of Washington, and Jane Train Flynn, of Rochester, N.Y., and 13 grandchildren. A third daughter, Marianne Train Hathaway, died in 1972.