I believe "Pecten glabra" or "Chlamys glabra" is a misspelling of Pecten glaber (Linne, 1758). However, I am amazed at how often "glabra" is used. Perhaps there is some disagreement over the correct spelling?? I have also seen fossil specimens labeled "Chlamys glabra". I don't know whether these actually are a different form, or are just fossil Pecten glaber. Paul M.