The position of dinocysts of the genera Scriniodinium, Endoscrinium, and Athigmatocysta in the family Gonyaulacaceae is discussed. It is shown that they were originally regarded as close morphotypes and changes in their taxonomy were associated with the evolution of views on some morphological features of the dinoflagellate shell as criteria for taxa of medium and high rank. It is proposed that the new subdivision is inconclusive, somewhat unnature, since it is based on the contentious details of tabulation. Morphological similarity of these dinocysts is indicated in the revised diagnosis of the genus Scriniodinium. The new cavate gonyaulacoid dinocyst species Scriniodinium multistratum sp. nov. from the Upper Volgian and Berriasian of the Nordvik section, northern Siberia, is described.