Bathurst Island lies north of Darwin, Northern Territory; it measures 2050 km2 Cenomanian marine argillaceous sediments are exposed in cliffs at the south coast, and were first reported and diagnosed to be of Cretaceous age by Daily in 1955. Molluscs collected from various outcrop localities were dated mid- to late Cenomanian by Wright in 1963. Gravity and seismic refraction surveys by petroleum companies since 1956established the presence of a considerable rock sequence of Mesozoic age. Subsequent regional field work by the BMR concluded that the Cenomanian strata probably accumulated in a shallow sea bordered in the north by scattered land areas. Two wells, Bathurst Island Nos. I and 2, penetrated the rock sequence at the south coast of the island to a depth of slightly over 300 m, and were continuously cored. Examination of ammonites and foraminifera established the sequence as Cenomanian to possibly lower Turonian.Samples from 20 cores from these wells were selected for palynological study. The results are presented in this Bulletin. The spores and pollen grains are thought to have been shed by temperate vegetation. The spore-pollen sequence is divided into 2 intervals, palynological unit K3a, of Cenomanian age, and palynological unit K3b, of possibly early Turonian age. Dinoflagellate Zone. Two subdivisions are distinguished: a lower Subzone, ofCenomanian age, and an upper Subzone, of late Cenomanian to possibly early Turonian age. In the descriptive and taxonomic work of the microplankton by M. S. Norvick, 104 dinoflagellate cyst and 16acritarch species, varieties, and species groups are differentiated, belonging to a total of 61 previously known genera. Eight new species of dinoflagellate cysts are described: and In the systematic study of the spores and pollen grains by D. Burger, 40 spore species and 23 pollen species are described or documented. Two new genera, and 7 new species are proposed: and 1956 established