Dear Friends,
 
Thank you for your clear answers. If I've correctly understood
there are 3 levels:
 
"Simple" collector (Art wrote) => Conchologist => Malacologist
 
with infinite inter-grades between them.  I think the CONCH-Lers
are mostly conchologists, few are "Simple" collectors and very
few are Malacologists.
 
After your messages I made a small research on these two words.
"Malacologist" is derived from ancient Greek "malakos" meaning
"soft" ("molle" in Italian).
The word "Conchologist" is derived from Latin "conchylium"
meaning "shell" ( "conchiglia" in Italian).
 
So that Paul Monfils is right when he wrote : " A malacologist is
a zoologist specializing in the philum Mollusca. A conchologist
studies/collects shells".
 
Thanks again !!
 
Ciao!!
 
Maurizio
from Italy.