1. J.B.C. Jackson is at the Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA, and the Smithsonian Tropical Research Institute, Box 2072, Balboa, Republic of Panama.
2. K. G. Johnson is at the Natural History Museum of Los Angeles County, 900 Exhibition Boulevard, Los Angeles, CA 90007, USA.