Dear Kurt et al;-
     Thank you for the reply. It seems that our present state does
simply leave divisions in the eye of the beholder---or under his
microscope.
     Here's something else I've wondered about. I have this lovely
Murex pecten with its great spikes and a few other almost similar
species. The spikes obviously serve as protection---but against what?
The spikes also probably keep the mollusk from doing much digging to
get away from preditors. Do other mollusks living in a similar biome
have other protections against similar predators? Do the appendages
on a carrier shell serve as protection---or just camoflage?
    You remember TV used to have the "Answer Man". I'm the "Question
Man".
             Art