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Spiniferites microceras ssp. opisthophorus
Spiniferites microceras ssp. opisthophorus(Cookson and Eisenack, 1974) Lentin and Williams, 1977
Originally Spiniferites microceras var. opisthophorus, subsequently (and now) Spiniferites microceras ssp. opisthophorus.
Holotype: Cookson and Eisenack, 1974, pl.22, fig.12
Age: Paleocene
Original diagnosis: Cookson and Eisenack, 1974, p.61: Spiniferites microcreas var. opithophorus
A variant of the Sp. microceras with antapical top-piece. Shell oval, thin-walled with short, broad-based apical horn, highly helicoidal girdle (cingulum) and slanted longitudinal furrow (sulcus). Processes very short, furcation hardly noticeable. Spanning-membrane only sporadically well developed - then, however, coarsely serrated. Antapical plate bordered by delicate membranes so that a low top-piece is formed, comparable to the one in the case of the Sp. cornutus var. opisthophorus.
Dimensions: shell about 52 x 57 µm, overall about 71 x 67 µm horn about 4 µm.
Occurrence: Rivernook Bed, Victoria; Paleocene.
Originally Spiniferites microceras var. opisthophorus, subsequently (and now) Spiniferites microceras ssp. opisthophorus.
Holotype: Cookson and Eisenack, 1974, pl.22, fig.12
Age: Paleocene
Original diagnosis: Cookson and Eisenack, 1974, p.61: Spiniferites microcreas var. opithophorus
A variant of the Sp. microceras with antapical top-piece. Shell oval, thin-walled with short, broad-based apical horn, highly helicoidal girdle (cingulum) and slanted longitudinal furrow (sulcus). Processes very short, furcation hardly noticeable. Spanning-membrane only sporadically well developed - then, however, coarsely serrated. Antapical plate bordered by delicate membranes so that a low top-piece is formed, comparable to the one in the case of the Sp. cornutus var. opisthophorus.
Dimensions: shell about 52 x 57 µm, overall about 71 x 67 µm horn about 4 µm.
Occurrence: Rivernook Bed, Victoria; Paleocene.