Named in honor of William David McElroy, distinguished biologist and biochemist, chairman of the biology department at Johns Hopkins University during 1956–1969, later director of the National Science Foundation (1969–1972) and chancellor of the University of California at San Diego (1972–1980). During his tenure as director of N.S.F. the U.S. government decided to fund the Very Large Array, which will be the pre-eminent instrument for radio astronomy for many years to come. (M 5450) _ _.