Hello Tom,

I have lost the link to your image pages.  If you can resend it, I'll be
glad to take a look at your new images.  However, there are only four
species of Pectinidae in your locality that exceed 70 mm - magellanicus;
maximus; islandica; and opercularis.  Chlamys islandica can be quite
variable, not only in color, but also in roughness of texture,
lenth-width ratio, thickness (some more inflated than others), and
weight (thickness of the actual valves).  I'm quite sure that's what you
have - as Ross said, a form of C. islandica.

Paul M.