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Aptea eisenackii
Aptea eisenackii, (Davey, 1969), Davey and Verdier, 1974
NOW Pseudoceratium. Originally Cyclonephelium, subsequently Aptea, thirdly (and now) Pseudoceratium.
Tax. jr. synonym of Aptea polymorpha Eisenack, 1958a, according to Cookson and Eisenack, 1974. Below, 1981a, retained Aptea eisenackii as a separate species.
Holotype: Davey, 1969, pl.8, figs.3-4; pl.9, fig.4
Locus typicus: Saskatchewan, Canada
Stratum typicum: Albian
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Original description as Cyclonephelium eisenacki: [Davey, 1969, p. 170]:
Diagnosis:
Shell subtriangular, flattened, with convex sides. Apical horn well developed; antapical horns, if present, very reduced. Greater part of shell surface ornamented by complex network of low crests and short, capitate processes. In centre of both dorsal and ventral sides there is a circular area devoid of ornamentation. Apical archaeopyle always present.
Description:
The shell surface is ornamented by a very characteristic network of low crests or lamellae which are often broken, so forming isolated processes. A poorly-marked cingulum, outlined by the crests, is occasionally discernible. The apical operculum is often in position.
Dimensions:
shell length 70-92 µm (4 complete specimens measured); shell length (operculum missing) 55 (63.1) 71 µm, width 66 (72.1) 84 µm, height of crests 2 (4.2) 7 µm.
NOW Pseudoceratium. Originally Cyclonephelium, subsequently Aptea, thirdly (and now) Pseudoceratium.
Tax. jr. synonym of Aptea polymorpha Eisenack, 1958a, according to Cookson and Eisenack, 1974. Below, 1981a, retained Aptea eisenackii as a separate species.
Holotype: Davey, 1969, pl.8, figs.3-4; pl.9, fig.4
Locus typicus: Saskatchewan, Canada
Stratum typicum: Albian
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Original description as Cyclonephelium eisenacki: [Davey, 1969, p. 170]:
Diagnosis:
Shell subtriangular, flattened, with convex sides. Apical horn well developed; antapical horns, if present, very reduced. Greater part of shell surface ornamented by complex network of low crests and short, capitate processes. In centre of both dorsal and ventral sides there is a circular area devoid of ornamentation. Apical archaeopyle always present.
Description:
The shell surface is ornamented by a very characteristic network of low crests or lamellae which are often broken, so forming isolated processes. A poorly-marked cingulum, outlined by the crests, is occasionally discernible. The apical operculum is often in position.
Dimensions:
shell length 70-92 µm (4 complete specimens measured); shell length (operculum missing) 55 (63.1) 71 µm, width 66 (72.1) 84 µm, height of crests 2 (4.2) 7 µm.