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Canningia microreticulata
Canningia microreticulata, (Brideaux and McIntyre, 1975), Below, 1981
Now Senoniasphaera. Originally (and now) Senoniasphaera, subsequently Canningia.
Lentin and Williams, 1981, retained this species in Senoniasphaera Clarke and Verdier, 1967.
Holotype: Brideaux and McIntyre 1975, pl.11, fig.7-9
Locus typicus: Horton River Formation, District of Mackenzie, Canada
Stratum typicum: Middle Albian
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Original description as Senoniasphaera microreticulata: [Brideaux and McIntyre, 1975, p. 35]:
Diagnosis:
Cyst two layered; the periphragm microreticulate and generally closely appressed to the thicker microreticulate endophragm. One apical prominence, and a rounded or asymmetrically developed antapex, and with cingular bulges.
Archeopyle apical; operculum simple and detached or partially attached ventrally.
Reflected tabulation, 4", 6", 0c, 5-?6""", 1"""".
Cingulum displaced one to two cingular widths; sulcus offset to the left.
Description:
The periblast outline is subcircular to ovoid with one apical prominence, a slight lateral bulging at the cingulum, and or rounded to asymmetrically developed antapex. Where asymmetrical development of the antapex occurs, the left antapical prominence is more pronounced. The periblast and endoblast are somewhat dorso-ventrally flattened.
The cyst possesses two distinct wall layers which, in well-preserved specimens, are closely appressed except at the apex, the cingular region, and at the antapical prominences. Specimens damaged by maceration, or by natural preservational processes, may show moderate to extreme detachment of the two layers.
The periphragm is a thin microreticulate layer which may be folded or otherwise produced so as to outline reflected tabulation. These folds lie along the course of raised and thickened microreticulate ridges on the underlying endophragm. In specimens from which the periphragm has been stripped, the endophragm can be seen to possess a variable microreticulate to microfossulate sculpture, and occasionally may bear apiculate sculpture. The periphragm,in damaged or degraded specimens, may appear to be connected to the endophragm by a network of fibrous processes. Well-preserved material dispels this impression.
The archeopyle is apical and has a zig-zag margin, indicating the presence of reflected tabulation. The operculum is simple, and may be detached and preserved separately, but is often found close to or partially attached ventrally to the rest of the cyst. The operculum is formed of apical reflected plates 1" to 4" in both the periblast and endoblast (Pl. 11, fig. 11). The reflected tabulation pattern is not clear in all details on each specimen, particularly in the case of the postcingular series. The scheme, as derived from a study of all available material, is: 4", 6", 0c, 5-?6""", 0p, 1"""". The presence of five postcingular reflected plates is confirmed on all well-preserved specimens. A sixth postcingular reflected plate appears to be present on a few specimens, but is not clearly shown.
A cingulum and sulcus are evident on all but the most poorly preserved material. The cingulum follows a slightly sinuous path and is displaced one to two cingular widths on the ventral surface. The sulcus is displaced to the left at its posterior end, is narrow anteriorly, and wide as posteriorly at its junction with the antapical reflected plate.
Dimensions:
Periblast: length, 112-140 µm; width, 75-126 µm; endoblast: length, 105-118 µm; width, 75-123 µm.
Affinities:
Senoniasphaero sp. of Davey and Verdier, 1971, p. 31, Pl. 6, figs. 7-9, is much smaller. Coming from the Upper Albian of Vallentigny, in northeastern France, it represents the only other Albian occurrence of the genus.
Now Senoniasphaera. Originally (and now) Senoniasphaera, subsequently Canningia.
Lentin and Williams, 1981, retained this species in Senoniasphaera Clarke and Verdier, 1967.
Holotype: Brideaux and McIntyre 1975, pl.11, fig.7-9
Locus typicus: Horton River Formation, District of Mackenzie, Canada
Stratum typicum: Middle Albian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Senoniasphaera microreticulata: [Brideaux and McIntyre, 1975, p. 35]:
Diagnosis:
Cyst two layered; the periphragm microreticulate and generally closely appressed to the thicker microreticulate endophragm. One apical prominence, and a rounded or asymmetrically developed antapex, and with cingular bulges.
Archeopyle apical; operculum simple and detached or partially attached ventrally.
Reflected tabulation, 4", 6", 0c, 5-?6""", 1"""".
Cingulum displaced one to two cingular widths; sulcus offset to the left.
Description:
The periblast outline is subcircular to ovoid with one apical prominence, a slight lateral bulging at the cingulum, and or rounded to asymmetrically developed antapex. Where asymmetrical development of the antapex occurs, the left antapical prominence is more pronounced. The periblast and endoblast are somewhat dorso-ventrally flattened.
The cyst possesses two distinct wall layers which, in well-preserved specimens, are closely appressed except at the apex, the cingular region, and at the antapical prominences. Specimens damaged by maceration, or by natural preservational processes, may show moderate to extreme detachment of the two layers.
The periphragm is a thin microreticulate layer which may be folded or otherwise produced so as to outline reflected tabulation. These folds lie along the course of raised and thickened microreticulate ridges on the underlying endophragm. In specimens from which the periphragm has been stripped, the endophragm can be seen to possess a variable microreticulate to microfossulate sculpture, and occasionally may bear apiculate sculpture. The periphragm,in damaged or degraded specimens, may appear to be connected to the endophragm by a network of fibrous processes. Well-preserved material dispels this impression.
The archeopyle is apical and has a zig-zag margin, indicating the presence of reflected tabulation. The operculum is simple, and may be detached and preserved separately, but is often found close to or partially attached ventrally to the rest of the cyst. The operculum is formed of apical reflected plates 1" to 4" in both the periblast and endoblast (Pl. 11, fig. 11). The reflected tabulation pattern is not clear in all details on each specimen, particularly in the case of the postcingular series. The scheme, as derived from a study of all available material, is: 4", 6", 0c, 5-?6""", 0p, 1"""". The presence of five postcingular reflected plates is confirmed on all well-preserved specimens. A sixth postcingular reflected plate appears to be present on a few specimens, but is not clearly shown.
A cingulum and sulcus are evident on all but the most poorly preserved material. The cingulum follows a slightly sinuous path and is displaced one to two cingular widths on the ventral surface. The sulcus is displaced to the left at its posterior end, is narrow anteriorly, and wide as posteriorly at its junction with the antapical reflected plate.
Dimensions:
Periblast: length, 112-140 µm; width, 75-126 µm; endoblast: length, 105-118 µm; width, 75-123 µm.
Affinities:
Senoniasphaero sp. of Davey and Verdier, 1971, p. 31, Pl. 6, figs. 7-9, is much smaller. Coming from the Upper Albian of Vallentigny, in northeastern France, it represents the only other Albian occurrence of the genus.