Lon Tuck, 49, a music critic at The Washington Post and a former managing editor of the newspaper's Style section, was found dead of epilepsy and heart ailments yesterday at his home in Washington.

A gentle and self-effacing man, Mr. Tuck was a student of classical music for much of his life. He once said that his education at Princeton University, from which he graduated in 1959 with a bachelor's degree in English, really had taken place at the Metropolitan Opera in New York City. Thus his work as a critic was an avocation as well as a profession and this showed in what he wrote.

The most important service a critic can perform for a reader is to say whether he liked whatever it is he is writing about, and why. Mr. Tuck was very good at this and in the process he conveyed his own strong feelings not only for the work at hand but for things musical in general.

His last review, which can stand as an example of much that he did, appeared on May 28 and it said:

"The greatly lauded Brooklyn Academy of Music concert versions of the Gershwins' twin musicals on the presidency, 'Of Thee I Sing' and 'Let 'Em Eat Cake,' opened last night at the Kennedy Center Opera House. And it makes the listener want to sing of it, too.

"It was the most joyful evening in the musical theater that I can recall in recent years."

And if he did not like what he was seeing or hearing, Mr. Tuck could convey that, too. His review last January of the Monteverdi opera, "The Coronation of Poppea," took thunderous exception to the production's translation of imperial Rome into the 20th century of mafiosi and paparazzi. "This lavish, muddled and monumentally tasteless assault upon Monteverdi . . . -- and upon the audience as well, for that matter," he said, "is a supreme example of the corruption of a great work into a bad dream."

On the other hand Mr. Tuck liked the singers.

Although music was his consuming interest -- he traveled to Europe and China to write about it -- Mr. Tuck also wrote about other aspects of classical culture and the people who are pleased to be its keepers. These pieces ranged from notable profiles of the pianist Vladimir Horowitz and the late Dr. Arthur M. Sackler, the entrepreneur of medical publishing and advertising who donated a museum and its contents to the Smithsonian Institution, to a story about a $1.4 million acquisition of folk art by the Smithsonian's National Museum of American Art.

And both as an editor and a writer in Style, Mr. Tuck was a persistent spokesman for the notion that highbrow and dull are not the same thing.

Mr. Tuck was born and raised in Sherman, Texas. After graduating from Princeton he studied law at the University of Texas for a year. He returned to the East to seek a career in journalism. He began at The Post as a copy boy in December 1961.

In March 1962, he became a reporter on the city staff and four years later he was named Virginia editor. He was one of the first editors on the Style section, which was started in the late 1960s, and there he found his role as a declarer for the arts. He was managing editor of the section from 1972 to 1976.

In 1976 and 1977, he went to the editorial page as a writer and assistant editor. He then returned to Style as an assistant editor and, finally, a music critic.

Survivors include his mother, Grace Tuck of Sherman.

MATTIE COOKE DYKE,

66, who was a teacher and interim principal during a 32-year career in the D.C. schools, died of cancer June 1 at the Washington Hospital Center. She lived in Lanham.

Mrs. Dyke began her career in 1944 at Smothers Elementary, then served on the faculties of Payne and Maury elementary schools. She spent about the last 10 years of her career at Bryan Elementary, where she was a head teacher and interim principal, before retiring in 1976.

She was a member of Sargent Memorial United Presbyterian Church in Washington, where she taught Sunday school for many years and had directed the Vacation Bible Class.

Mrs. Dyke was born in Spencerville, Md., and was educated in Montgomery County and D.C. schools. She was a 1940 graduate of Cardozo High School and was a cum laude graduate of the old Miner Teachers College.

Survivors include her husband, James Webster Dyke Sr. of Lanham; a son, James Webster Dyke Jr., and a brother, William B. Cooke, both of Washington; six sisters, Mary C. Bacon of Sandy Spring, Margaret C. Davis of Queens Chapel, Md., Edythe D. Pratt of Lanham, and Helen C. Bonds, Pearl C. Parker and Emma C. Willis, all of Washington, and four grandchildren.

DR. HERMAN L. KAMENETZ,

79, a retired chief of rehabilitation medicine service at the Veterans Administration Hospital in Washington, died June 2 at Arlington Hospital after a heart attack. He lived in Arlington.

Dr. Kamenetz was born in Russia. He earned his degree in medicine from the University of Paris. He moved to the United States in 1953 and became an assistant clinical professor of physical medicine at Yale University. He also became chief of the rehabilitation department of the Connecticut State Hospital in Rocky Hill, Conn.

He moved to the Washington area in 1975 and joined the staff at the Veterans Administration Hospital. He retired in 1983. During those years, he also had been a clinical professor of medicine at George Washington University and a lecturer at Georgetown University.

Dr. Kamenetz's books include "The Wheelchair Book: Mobility for the Disabled" and "The Dictionary of Physical Medicine and Functionary Adaptation," which was written with his wife and published in French in 1972.

He was a member of the American Medical Writers Association and a diplomate of the American Board of Rehabilitation Medicine.

Survivors include his wife, Georgette Kamenetz of Arlington.

ALFRED L. CAVES,

68, a part-time real estate salesman and retired employe of the old Atomic Energy Commission who was a member of Peoples Congregational Church in Washington, died May 27 at Holy Cross Hospital after a heart attack. He lived in Washington.

He worked for the AEC for 26 years before retiring in 1974 as an internal security specialist. He had sold real estate for a number of area firms since the 1950s.

Mr. Caves, who moved to this area in 1941, served with the Army during World War II. He was a graduate of what was then West Virginia State College. He was a member of the Akos Investment Society and the Seven Aces.

Survivors include his wife, Dorine, and a brother, William, both of Washington.

JOHN J. GILL JR.,

78, a retired federal government accountant, died June 2 at George Washington University Hospital. He had a heart ailment.

Mr. Gill, a resident of Chevy Chase, was born in Carbondale, Pa., and graduated from Rider College.

Before moving to the Washington area in 1948, he was an Agriculture Department accountant in Albany, N.Y. He retired in 1972 after 39 years of federal service, 16 with the Department of Agriculture and 23 with the Department of Defense.

He was a member of the Shrine of the Most Blessed Sacrament Catholic Church in Washington.

Survivors include his wife of 49 years, Marjorie Gill of Chevy Chase; one son, John J. Gill III of Alexandria; one daughter, Margie Cavanaugh of Bowie; five sisters, three brothers, and six grandchildren.

JOHN FRANCIS MONAHAN III,

25, a messenger with I.G.E. Expediting Inc., a courier service, was killed on May 28 in a bicycle accident at 4th and Rhode Island Ave. NE. He lived in Riverdale.

A spokesman for the D.C. police said Mr. Monahan was making a right turn from 4th Street on to Rhode Island Ave. when he lost control of his bike and struck his head on a curb. Police said he was wearing a protective helmet.

Mr. Monahan was born in Washington. He graduated from Dematha High School and the University of Maryland. He worked for Acumenics Research and Technology Inc. in Fairfax before joining I.G.E. in October.

He was an intern with the Maryland State Legislature during the 1982 session and had sponsored a child in an African country through the Save the Children organization. He was a member of St. Pius Tenth Catholic Church in Bowie.

Survivors include his parents, John F. and Patricia A. Monahan, two brothers, Timothy and Mark, and two sisters, Patricia M. and Mary Ellen Monahan, all of Bowie, and a grandmother, Cecilia P. Murphy of Basking Ridge, N.J.

MARTHA STRAYER PAXTON,

70, an office assistant in the Fairfax law firm of Carman and Evans, died June 1 at Georgetown University Hospital. She had cancer and a heart ailment.

Mrs. Paxton, a resident of Arlington, was a fourth-generation Washingtonian and a graduate of the old Western High School and George Washington University. She had worked for Carman and Evans for the last 10 years and worked for about 20 years before that for several other Northern Virginia law firms.

Her husband, J. Webster Paxton, died in 1976. Survivors include two daughters, Carlin Hunter of Arlington and Emily Spencer of Mouth of Wilson, Va.; one sister, Mary Mathisen of Arlington, and two grandchildren.

JOHN L. McCONNELL,

61, a vice president in the Washington offices of the New York Stock Exchange, died of cancer June 2 at his home in Potomac.

He came to this area in 1965 and became an executive assistant to Sen. Russell Long (D-La.). Mr. McConnell had worked for the stock exchange since 1969.

Mr. McConnell was born in Alexandria, La. He graduated from Northwestern State University in Lousiana. During World War II, he served in the Navy in the Pacific. During the 1950s, he published a newspaper in Coushatta, La., and was a reporter with the Alexandria, La., Town Talk.

Mr. McConnell had been active with the Montgomery County Boys Home. He was a member of Good Shepherd Episcopal Church in Silver Spring, where he had served on the vestry.

Survivors include his wife, Gene McConnell of Potomac; three daughters, Paula Seesman of Gaithersburg, Karen Demers of Germantown, and Johnell McConnell of Potomac; a son, John N. McConnell of Germantown; a brother, Thomas E. McConnell of New Orleans, and four grandchildren.

LEON W. DADE,

88, a retired railway postal employe, died of a heart ailment June 1 at Capitol Hill Hospital.

Mr. Dade was a lifelong resident of Washington and a graduate of Dunbar High School. He attended the old Miner Normal School.

He joined the old Post Office Department as a railway mail clerk in 1926 and retired as a general foreman in the railway mobile unit in 1965.

Survivors include his wife, Mildred Clementine Dade of Washington; one stepson, Bernard L. Crawford Sr. of Fort Washington; six grandchildren, and one great-grandchild.

VASILIKY C. ROUMEL,

94, who owned and operated a salted nut business and a real estate management and development firm with her husband, died of cardiac arrest June 1 at her home in Washington.

Mrs. Roumel was born in Greece. She moved to this country in 1914 and settled in Wilmington, Del. She came to the Washington area in 1918.

During the 1920s and the '30s, she and her husband Constantine Roumel sold salted nuts wholesale and operated the OK Nut Co., a retail outlet. They also had a real estate management and development business. She retired in about 1946. Her husband died in 1965.

She was a member of St. Sophia Greek Orthodox Cathedral in Washington.

Survivors include two sons, Theodore and Aristotle Roumel, both of Washington; one brother, Arthur T. Androus of Alexandria; two sisters, Alexandra Bouzoucos of Hamden, Conn., and Stella Nicouloudis of Hope Well, Va., and three grandchildren.