1. Department of Biological Sciences and Museum of Natural Sciences, 119 Foster Hall, Louisiana State University, Baton Rouge, Louisiana 70803.
2. Current address: Department of Ecology and Evolutionary Biology, 621 Charles E. Young Drive South, University of California Los Angeles, Los Angeles, California 90095.
3. Section of Integrative Biology and Texas Memorial Museum, University of Texas, Austin, Texas 78712.
4. Current address: Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182.