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Alterbia eyrensis
Alterbia? eyrensis, (Cookson and Eisenack, 1971), Lentin and Williams, 1976
Combination illegitimate: the generic name Alterbia is illegitimate.
Questionable assignment: Lentin and Williams (1976, p.49).
Holotype: Cookson and Eisenack, 1971, pl.7, fig.3
Locus typicus: Eyre Bore No. 1 core 20, Western Australia.
Stratum typicum: Mid-Cretaceous
Age: Albian-Cenomanian.
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Original description as Deflandrea eyrensis: [Cookson and Eisenack 1971, p. 217-218]:
Description:
Shell considerably longer than broad, resembling in that respect D. bakeri Deflandre and Cookson (1955) and D. scheii Manum (1963). Epitheca longer than the hypotheca, dome-shaped with a very short centrally-placed apical horn. Hypotheca with convex sides which slant towards a very short antapical prominence situated towards the lefthand side of the dorsal surface. Girdle circular and rather broad (Pl. 7, fig. 3). Wall of shell thin, slightly to rather coarsely and densely granular especially in the upper portion of the epitheca. Capsule relatively large, roughly oval in shape but not reaching the lateral walls of the shell. Surface closely granular varying somewhat in the degrees of density.
Archeopyle relatively small, when clearly developed, as in the holotype, six-sided.
Dimensions:
Holotype: shell c. 90µ x 56 µm, capsule c. 60 µm x 60 µm.
Range from shell c. 72 µm x 45 µm, capsule c. 48 µm x 42 µm to shell c. 121 µm x 82 µm, capsule c. 80 µm x 60 µm.
Remarks:
D. eyrensis has occurred frequently in preparations of the Eyre deposit core 20. As the illustrations show, a considerable degree of variation both in the density and coarseness of the ornament of the shell occurs.
Combination illegitimate: the generic name Alterbia is illegitimate.
Questionable assignment: Lentin and Williams (1976, p.49).
Holotype: Cookson and Eisenack, 1971, pl.7, fig.3
Locus typicus: Eyre Bore No. 1 core 20, Western Australia.
Stratum typicum: Mid-Cretaceous
Age: Albian-Cenomanian.
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Original description as Deflandrea eyrensis: [Cookson and Eisenack 1971, p. 217-218]:
Description:
Shell considerably longer than broad, resembling in that respect D. bakeri Deflandre and Cookson (1955) and D. scheii Manum (1963). Epitheca longer than the hypotheca, dome-shaped with a very short centrally-placed apical horn. Hypotheca with convex sides which slant towards a very short antapical prominence situated towards the lefthand side of the dorsal surface. Girdle circular and rather broad (Pl. 7, fig. 3). Wall of shell thin, slightly to rather coarsely and densely granular especially in the upper portion of the epitheca. Capsule relatively large, roughly oval in shape but not reaching the lateral walls of the shell. Surface closely granular varying somewhat in the degrees of density.
Archeopyle relatively small, when clearly developed, as in the holotype, six-sided.
Dimensions:
Holotype: shell c. 90µ x 56 µm, capsule c. 60 µm x 60 µm.
Range from shell c. 72 µm x 45 µm, capsule c. 48 µm x 42 µm to shell c. 121 µm x 82 µm, capsule c. 80 µm x 60 µm.
Remarks:
D. eyrensis has occurred frequently in preparations of the Eyre deposit core 20. As the illustrations show, a considerable degree of variation both in the density and coarseness of the ornament of the shell occurs.