For communication of results before publication and comments on the manuscript, the authors are greatly indebted to Tom Blumenthal, Paul De Ley, Scott Emmons, Jim Garey, Bob Goldstein, Richard Gordon, Tom Johnson, Karin Kiontke, Armand Leroi, Patrick Phillips, Einhard Schierenberg, David Shook, Ralf Sommer, Walter Sudhaus, and an anonymous reviewer.