“Among the 566 extinct mollusk species, 400 are from oceanic islands, representing 71% of all listed mollusk extinctions. And among these 400 extinct mollusk species,327 are endemic to the most isolated islands of the world.”
Pacific islands – 225 species/subspecies
North America – 90
Asia – 59
Mascarene Islands – 49
Europe – 38
West Indies – 27
South/Central America – 21
Oceania – 13
Macaronesia – 11
Africa – 3
Others – 30
Reference: RÉGNIER, C., FONTAINE, B., & BOUCHET, P. (2009). Not Knowing, Not Recording, Not Listing: Numerous Unnoticed Mollusk Extinctions Conservation Biology