Some Eocene and Oligocene Phytoplankton from the Gulf Coast, U.S.A.

Abstract

Four distinctive new dinoflagellate species are described from the Gulf Coast Tertiary. Two of these are made the bases for new genera: Phthanoperidinium, type species P. amoenum from the Oligocene of Mississippi, and Heteraulacacysta, type species H. campanula from the Eocene of Alabama. These genera are made the bases for the new families Phthanoperidiniaceae and Heteraulacacystaceae. A new species of Homotryblium is described from the Oligocene of Mississippi and one of Operculodinium from the Eocene and Oligocene. The new combination Heteraulacus polyedricus (Pouchet) is made for the former Peridinium. Two new acritarch genera Ascostomocystis and Cyclopsiella, each have two new species. The species Ascostomocystis hydria occurs in the Alabama Eocene and A. potane in the Mississippi Oligocene. Both Cyclopsiella elliptica and C. vieta occur in the Oligocene of Mississippi.