I think it can be both; see http://genealogy.about.com/cs/surname/a/italian_surname.htm http://genealogy.about.com/cs/surname/a/italian_surname.htm. Take heart

I think it can be both; see http://genealogy.about.com/cs/surname/a/italian_surname.htm http://genealogy.about.com/cs/surname/a/italian_surname.htm. Take heart in the fact that Joan of Arc's last name, which was probably Darc, was reinterpteted as d'Arc and transmogrified in English into "of Arc".