Notes on the systematics, morphology and biostratigraphy of fossil holoplanktonic Mollusca, 14. A new species of Vaginella (Gastropoda, Euthecosomata, Cavoliniidae) from the Late Oligocene of the North Sea Basin and its bearing on Chattian biostratigraphy

A new pteropod species, Vaginella basitruncata, is erected on the basis of material from the Late Oligocene (Chattian A) ’Kasseler Meeressand’ in Hessen (Germany). It is the oldest representative of this genus known from the North Sea Basin, and is characterised by shedding of the larval shell, a straight ventral apertural margin and by the absence of a preapertural constriction and apertural folds. Some notes on the biostratigraphical implication of pteropod distributions during the Late Oligocene within the North Sea Basin are added, and it is concluded on this evidence that the ’Kasseler Meeressand’ is coeval with the basal portion of the Grafenberg Sands in the Lower Rhine area (Germany). A subdivision of pteropod zone 16 into three subzones covering the Eochattian appears to be feasible. The so-called ’Sternberger Gestein’ is of middle and late Eochattian age (Chattian A/B, pteropod subzones 16b-c).