W. Richard Walsh, 58, a professor of American History at Georgetown University since 1954 and the author of books on American Colonial history, died of cardiac arrest Friday at Montgomery General Hospital. He lived in Rockville.

Prof. Walsh, an authority on American Colonial history, also lectured at seminars in that subject at Columbia University.

He was the author of two monographs, "The Writings of Christopher Gadsden" a prominent Colonial statesman from South Carolina, and "Charleston's (S.C.) Sons of Liberty." He also wrote "The Mind and Spirit of Early America: Sources in American History 1607-1789," a standard in its field now in its second printing.

From 1958-67, Prof. Walsh was editor in chief of the Maryland Magazine of History. He also edited a history of the state of Maryland, "Maryland: A History 1632-1974," published in the mid-1970s by the Maryland Historical Society.

In addition, he published numerous articles in historical journals.

Prof. Walsh was born in Brooklyn, N.Y. He earned a bachelor's degree from The College of Charleston in South Carolina, a master's degree in history from Syracuse University and a doctorate in history from the University of South Carolina.

In World War II, he flew combat missions in the Pacific as a Marine Corps aviator.

Survivors include his wife, Betty, a son, Bradley, and three daughters, Elizabeth, Linda and Army Sgt. Julia Walsh, all of Rockville; his mother, Anna Walsh, and two sisters, Anne Wielar and Margaret Hallock, all of Long Island, N.Y.