Recent collecting on the Tortuga Terrace, south of the Dry Tortugas Islands, has yielded several large new species of gastropods, including Chicoreus riverai Petuch and Berschauer, new species (Muricidae), Fasciolaria riverai Petuch and Berschauer, new species (Fasciolariidae), and Scaphella mercedesae Petuch and Berschauer, new species (Volutidae). These additions to the Gulf of Mexico molluscan fauna are described here and the importance of the Tortuga Terrace as an evolutionary “Hot Spot” is discussed. Sanibel Island, Lee County, Florida” is designated as the type locality for Fasciolaria tulipa which had no official stated type locality.