ABSTRACT
The Western Atlantic Region spans the entire eastern coasts of North and South America, from Labrador and Arctic Canada south to Patagonia and the Strait of Magellan. The Northwestern Atlantic Paratropical Subregion encompasses a single major biogeographical unit, the Carolinian Molluscan Province. This area, which extends from Cape Hatteras, North Carolina, to the Dry Tortugas, Florida Keys, and the entire Gulf of Mexico contains main suites of endemic taxa: one along the southeastern United States and the other within the Gulf of Mexico. The Carolinian Molluscan Province, named for North and South Carolina is, faunistically and ecologically, one of the most diverse areas in the Western Atlantic Region. The Carolinian Province is also noteworthy in containing a remarkable radiation of the family Modulidae, the largest known from anywhere in the world. Like the Florida Keys and the Floridian Subprovince, the Yucatanean Subprovince contains near-tropical oceanographic conditions, with water temperatures being warm enough, year round, for extensive coral reefs to flourish.
