Named in honor of William A. Cassidy (1928– ), geologist at the University of Pittsburgh. He was a pioneer investigator of tektite strewn fields and meteorite-impact craters. At the Vampo del Cielo in Argentina he documented one of the first known occurrences of multiple impact craters intimately associated with meteorite masses. For 15 years he led meteorite recovery teams on glacial stranding surfaces in Antarctica and was responsible for the acquisition of several thousand meteorites there, including lunar and martian specimens. He has investigated crystallization in plasmas simulating dust condensation in stellar atmospheres and vapor-deposition processes on surfaces simulating the moon and planets. (M 29142) _ _.