I would like to thank all the staff at museums, who helped to make stays at their institutions successful, helped with library research, and made specimens available for study: Henk Mienis (HUJ), Kathie Way, Julia Freeman, and Joan Pickering (BMNH), Alison Trew (NMW), Yves Finet and Claude Vaucher (MHNG), Roger Pickery (KBIN), Raye Germon, Jerry Harasewych, and Alan Kabat (USNM), James McLean and Lindsey Groves (LACM), Paul Scott and Henry Chaney (SBMNH), Terrence Gosliner (CASIZ), David Lindberg (UCMP), Paula Mikkelsen (DMNH & AMNH), Gary Rosenberg and Ned Gilmore (ANSP), Peter Jung (NHB), Philippe Bouchet, Pierre Lozouet, and Philippe Maestrati (MNHN), Margaret Gosteli (NMBE), Kenneth Boss (MCZ), Winston Ponder (AMS), Shirley Slack-Smith (WAM), and Eike Neubert (SMF).

Various specimens were kindly made available by Ted Baer, Franziska Brantschen, Verena and Dominik Brantschen-Geiger, Anuschka Faucci, Marc Girona, Mark Jones, Joan Koven (Astrolabe Inc., Washington, D. C.), Roger Pickery, Solly Singer, Katharine Stewart, Don Barklay, and Wolfgang Wranik.

Additional information was provided by Takenori Sasaki (Tokyo University).

The staff at Hancock Library at USC helped to locate many obscure references.

The visits of DMNH and ANSP were made possible through a DuPont Merck Scholarschip in Malacology, and a Jessup Fellowship, respectively. Research resulting in some of the new anatomical data reported here was supported by grants from the Hawaiian Malacological Society, the Western Society for Malacology, and the Lerner Gray Fund for Marine Research (AMNH). The visit at AMS was made possible by an AMS Collection Fellowship. I express my gratitude to all these persons and institutions.

My appreciation goes to the Palo Alto Research Center of Xerox for offering the free map site on the wold wide web.

Photographs of live specimens were generously made available by Hank Chaney, Terry Gosliner, Karen Gowlett-Holmes, Bill Rudman, Solly Singer, and Urs Wüest.