Oh, the perils of buying old collections, especially since relatives often do not understand the concept of "correct data."  I really smell a rat with this shell.   I have a yellow pecten that seems to fit the description of Chlamys rubida, but it  was labeelled Chlamys "patraiae (Doella Jurado, 1918)"   Also, the locality is "Maldonado, Uruguay."  COMMENTS?        Cheers, Linda