On Nannoconus abundans nov. spec, and on Laminated Calcite Growth in Lower Cretaceous Nannofossils

Nannoconus abundans nov. spec, is described and illustrated by lightmicrosco py (LM), trans­ mission- (TEM) and scanning electronmicroscopy (SEM). Its composition of laminated calcite rhombohedrons arranged in a spire around an axial canal is compared with the ultrastructure of other types of nannoplankton fossils. Additional calcite growth, in vivo or post mortem, in the genus Watznaueria (Coccolithineae) results in similar patterns of crystal arrangement on the proximal side preferably. Thus a phylogenetic relationship between the Coccolithineae and the Nannoconideae, which hitherto are considered "incertae sedis", seems to be possible.