Peridinium basilium Drugg, 1967

Originally Peridinium, subsequently Palaeoperidinium.
Tax. jr. synonym of Palaeoperidinium pyrophorum (Ehrenberg, 1838) Sarjeant, 1967, according to Stover and Evitt, 1978.
Holotype: Drugg, 1967, pl.1, fig.11
Locus typicus: Fresno County, Escarpado Canyon, California
Stratum typicum: ?Maastrichtian-Danian

Original diagnosis: Drugg, 1967, p.13
Test flattened, five-sided in outline, apical and antapical horns usually reduced. Peridinioid tabulation present but indistinct. A partial reconstruction of the tabulation is shown on plate 9, figure 1a-b. Girdle always present, borders distinct, sometimes slightly denticulate. Longitudinal furrow not prominent. An internal body is often, but not always, present. This body varies considerably in shape and in distinctness. Usually the outline of the internal body parallels that of the outer test and the exact limits of the inner body are hard to define. On some specimens, however, the internal body is very distinct, relatively compact, and circular in outline. The test tends to divide along the girdle leaving the internal body, when present, intact.
Dimensions: The dimensions of the test range from 60 to 111 µm wide, and 78 to 118 µm high.