morphogenesis

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Composition and Structure of the Ventriculitidae (Porifera, Hexactinellida) Family

The Ventriculitidae representatives used to hold noticeable and occasionally dominant position within the Coniacian – Maastrichtian sponge assemblages. Relatively simple skeleton construction in the representatives of the family among the Late Cretaceous hexactinellids has made it possible to trace variations in skeleton morphology, changes in the goblet habitus and in the structure of irrigation system depending on the width variations of the skeleton-building wall.

On the Genus Balantionella Schrammen, 1902 (Porifera, Hexactinellida)

The Balantionella genus has been recognized by A. Schrammen (1902) from a single specimen and two skeleton fragments from a locality in the «quadrate» Cretaceous rocks in Germany. In the southeast of the Russian Plate, representatives of the genus have been determined within units from all the stages of the Upper Cretaceous. This has made it possible to provide characteristics and to trace the morphogenetic tendencies in the representatives of the group. Three subgenera and 12 species have been recognized.