Some New and Stratigraphically Useful Calcareous Nannofossils of the Cenozoic

Abstract

Fifteen new species of calcareous nannofossils of probable stratigraphic significance are described here. Several of these-Cyclococcolithus macintyrei, Discoaster neohamatus, Discoaster quintatus, Helicopontosphaera sellii, Micrantholithus procerus, Sphenolithus anarrhopus, Sphenolithus neoabies, Thoracosphaera prolata, and Triquetrohabdulus inversus-are among taxa known to be abundant with wide geographic ranges and thus particularly useful in developing worldwide zonations. This usefulness has been evident during preliminary studies of Deep Sea Drilling Project cores, and naming the taxa, therefore, is important. Other new species-Helicopontosphaera papillata, Leptodiscus larvalis, Pemma snavelyi, Quinquerhabdus colossicus, Syracosphaera Formosa, and Syracosphaera labrosa-are presently known only from restricted regions or constitute only a minor part of worldwide assemblages. They, too, may prove useful because they are easily identified and seem to have restricted time ranges.