Thanks Maurizio. Joe here.  What a Great insight into the history of
words you provided. I studied Latin for several years and found it the
most interesting subject I ever took. I envy you Italians with so much
History...the Romans; the Catholic church...the Renaissance.. and on and
on.... When I visited Italy  I was overwhelmed with so much to see and
study.  My Latin came in handy in recent years.  At the Geological
Survey of Canada I have often helped geologists 'Latinize' their new
taxonomic names...agree species to genus...etc.  If any of you have
taken Latin, how can one begin to explain all the permutations of
Declensions, Case etc.? How does one explain that the ending of a
species is ... for example..because it is a second declension noun, not
masculine or neuter but a rare feminine exception, etc?...geesh; only
fellow Latin geeks could sympathize. No wonder conchologists get
confused when there are genus or species name changes.

 One small point. Isn't the Latin word pecus the word for cattle and not
sheep.? at least I think it was earlier on. Maybe the word has evolved
since then to mean sheep. Please keep us posted on the roots of some of
our shell names. It adds another fascinating angle to the study of
conchology.