The Reef Tract Assemblage:                                    After (p.49), AMOCO Seminar on Stratigraphic Principles.    

    This is the open-water assemblage characteristic of the lime sand areas of the Reef Tract. It has over a hundred mollusk species and is dominated by the microgastropod Caecum. Great variety of species and low numbers of specimens of any one type (other than the Caeci) are characteristic. The large mollusks, like Strombus occur here.