Named in honor of John E. Guest, reader in Planetary Studies at University College, London, and a colleague of the discoverer at the University of London Observatory during the latter§ postgraduate days. A leading British planetary geologist and a specialist in vulcanology, Guest has worked on the geological mapping of the moon, Mars and many of the atmosphereless satellites of the major planets. He was a principal investigator on the Soviet Phobos missions and is currently a team member on the Magellan radar-mapping mission to Venus. Guest has not neglected research on terrestrial vulcanology, however, as witness his book on Etna. (M 16594) _ _.