New taxa of hexactinellid sponges: Umbrelliserus olferjevi, gen. et sp. nov. (Coeloptychiidae) from the Maastrichthyan of the Volga river basin, Russia and Turbiplana nerodenkoi, gen. et sp. nov. (Leptophragmidae) from the Cenomanian of Ukraine are described. Study of skeletal remains of the described sponges allows to confirm proposed earlier basic trends in morphogenesis of the Upper Cretaceous hexactinellids. It also is evidence of reliability of worked out principles of Cretaceous Hexactinellida systematic on a familial level.
