Linda, Don't forget the possibility that fossil Chesapecten can be washed out of old strata. At many localities along the eastern and southern U.S., ancient deposits are eroded from cliffs or even below water, releasing fossil shells that sometimes look like they were alive a few days ago. According to Michal Kowalewski (Virginia Tech, Blacksburg), radiocarbon dating shows that beach shells are commonly one to several thousand years old, having been buried and reworked many times. Fragile shells do not last as long as more robust shells. It is sobering to realize that dead-collected material may represent thousands of years of shifting fauna, all averaged over time -- incidentally underscoring the need to collect live as well as dead shells for environmental studies. Andrew K. Rindsberg Geological Survey of Alabama