Peridinium eocenicum Cookson and Eisenack, 1965

Now Phthanoperidinium?. Originally Peridinium, subsequently (and now) Phthanoperidinium?.
Possible tax. sr. synonym of Phthanoperidinium stockmansii (de Coninck, 1975) Lentin and Williams, 1977, according to Stover and Evitt, 1978.
Possible tax. sr. synonym of Phthanoperidinium resistente (Morgenroth, 1966) Eisenack and Kjellstr÷m, 1971, according to Stover and Evitt, 1978.
Holotype: Cookson and Eisenack, 1965, pl.11, figs.1-2
Locus typicus: Browns Creek Clays, SW. Victoria
Stratum typicum: Late Eocene

Original description: Cookson and Eisenack, 1965, p.119
Shell small, oval, tabulated and divided almost equally by a relatively broad, helicoid girdle. Both epitheca and hypotheca with a small, solid horn. Wall of shell finely granular with or without small dot-like thickenings of variable size on the surface of the plates (Pl. 11, fig. 5). The borders of the girdle and the thin transparent ledges of the plates are lightly granular and their edges dotted with evenly spaced granules and small tubercles, or sparsely denticulate.
Tabulation is of the Peridinium type, 4"?, 3[a], 7", 5""", 1p, 2"""". Plate 1" is kite-like in shape, the two upper sides of the "rhomb" being shorter than the two lower Plate 1""" is very narrow. Intercalary strips are sometimes evident. The archeopyle is relatively large, hexagonal, and intercalary.

Dimensions:
Holotype c. 60 µm long, 40 µm broad. Range c. 48-62 µm long 33-48 µm broad.