Carlos,
 
Nice to hear from you.  I'll leave the distribution questions to those with
a better reference library except I do have Weaver and Dupont who say in
"The Living Volutes," Cymbium olla occurs in deep water from "the southern
coast of Spain south-southeast to Oran, Algeria, then south along the
northwest coast of Africa to Agadir, Morocco."  And as for the genus eulima,
the quickest (what a great publication) reference is Tom Rice's price guide
which puts it in the family, Eulimidae.  However, my guide is old so it may
have changed.
 
Good luck with the Ceritium vulgatum.
 
Tom Eichhorst in New Mexico, USA