Nannotax

Description: Coccoliths are placoliths with rim structure similar to Coccolithus: V-unit forms both distal shield and lower cycle of central-area; R-unit forms both proximal shield and upper cycle of central-area.

Genera included:

	Coccolithus - dominant genus, with central area open, spanned by a disjunct or delicate axial cross (separation from Cruciplacolithus is tenuous)
	Clausicoccus - central area covered by perforate plate, common in the Palaeogene, and extends into Early Miocene
	Coronocyclus - open ring-like coccolith without shields, elements of rim complexly intergrown, apparently with outer V-unit and inner R-unit
	Cruciplacolithus - with disjunct axial cross in central area
	Hughesius - with central plate formed of 4 or fewer disjunct elements
	Solidopons - with narrow rim spanned by oblique disjunct bridge
	Chiasmolithus, Sullivania - Palaeogene genra with diagonal cross in central area

Remarks: