1. Department of Paleobiology, National Museum of Natural HistorySmithsonian InstitutionWashington, DC20560U.S.A.
2. L. H. Bailey HortoriumCornell UniversityIthacaNY14853‐4301U.S.A.
3. Department of BiologyUniversity of MichiganAnn ArborMI48109‐1048U.S.A.