Thanks Andy!
Wow! What a wealth of information! I think part of your post may answer my
question re: Personidae/Distorsiidae. I'll have to reread it more carefully
to be sure.
Any thoughts on where Potamididae came from? As far as I know there is not,
nor has there ever been an extant genus Potamida (or Potamidus/Potamidum).
Could it be this family was named after a fossil genus?
Regards,
Paul M.
Response to Kurt's last post, to avoid an extra posting by me:
Why break them? Couldn't resorption be determined by x-raying the shells?