Hystrichodinium patriciae (Neale and Sarjeant 1962) Lentin and Williams 1975

Originally Heliodinium, subsequently (and now) Hystrichodinium.
Possible tax. jr. synonym of Hystrichodinium oligacanthum Deflandre and Cookson, 1955, according to Backhouse, 1988. Sarjeant in Lentin and Williams, 1989, considered Hystrichodinium patriciae to be a separate species.
Holotype: Neale and Sarjeant, 1962, pl.19, fig.3
Paratype: Neale and Sarjeant, 1962
Locus typicus: Speeton Clay, Heslerton, England
Stratum typicum: Hauterivian

Original diagnosis: Neale and Sarjeant, 1962, p. 451: Heliodinium patriciae
A species of Heliodinium having an oval theca, with a well-marked transverse furrow dividing it into two Unequal halves. From the crests delimiting plates arise long spines, flat and ribbon-like, tapering gradually to closed points; the length of the spines exceeds the long diameter of the shell. Longitudinal furrow apparently present; detail of tabulation not determined.

Original description: Neale and Sarjeant, 1962, p. 451: Heliodinium patriciae
Theca yellowish, thick-walled, not or only very minutely granular. Transverse furrow of moderate breadth, dividing the theca into two unequal parts, one of which (?epitheca) is a half oval, the other a hemisphere. The ribbon-like spines are very flexible and much folded; they form a tangled mass around the theca which prevents determination of the tabulation.
Dimensions: Overall length 125 Ám, breadth 97 Ám. Shell length 43.5 Ám, breadth 40.5 Ám.