Large elliptical to almond-shaped Helicosphaera with well defined birefringent blanket in XPL and a central area spanned by a broad, oblique, disjunct birefringent bar.
Elliptical Helicosphaera with well defined birefringent blanket in XPL and narrow central area spanned by a conjunct bar.
Like H. compacta but with a truncated flange
Broadly rhombohedral Helicosphaera with a moderately well-developed spur in some specimens and a broad, oblique (high angled) disjunct bar. Distal surface covered by a blanket with multiple perforations, some large.
Large Helicosphaera with birefringent blanket, indistinct but disjunct, birefringent oblique bar, and anterior spur.
Elliptical Helicosphaera with relatively wide central area spanned by a broad, oblique disjunct bar.
Elliptical, oblong or reniform Helicosphaera with wide flange and central area spanned by a broad, near-longitudinal disjunct bar usually with distinct median suture.
Broadly rhomboidal; blanket with numerous perforations extending over the central area and covering the bar
Large, broadly elliptical Helicosphaera; central area narrow, with oblique, disjunct, broad bar. The coccolith is relatively birefringent across the width of the rim.
Elliptical Helicosphaera with relatively wide central area spanned by a broad tranverse to slightly-oblique disjunct bar.
Helicosphaera with relatively wide central area spanned by a broad tranverse to slightly-oblique disjunct bar and a flange that ends in a spur.
