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Cannosphaeropsis thule
Cannosphaeropsis thula, Davey, 1982
Holotype: Davey, 1982, pl.8, fig. 8-11; Riding and Davey, 1989, pl.1. fig.4
Locus typicus: West Abbey, Norfolk, England
Stratum typicum: Early Ryazanian
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Original description: Davey, 1982, p. 26-27
Diagnosis:
Shape: The pericyst, excluding processes, is ovoidal to noviform with very little dorso-ventral flattening.
Wall: The cyst wall is apparently two-layered, the two layers being closely appressed except where the periphragm alone forms the processes. The wall is of moderate thickness and the surface is smooth to little pitted.
Paratabulation: Parasutures are occasionally visible along the paracingulum and, more rarely, surrounding the parasulcal area.
Processes: These are parasutural in position. The gonal processes are trifurcate distally whereas the parasutural processes bifurcate distally. The furcations join with neighbouring ones to form a trabeculum which reflects the paratabulation. Distally the trabeculum bears small spines. The processes are longest on the dorsal hypocyst and decrease in size away from this region, being lowest on the ventral epicyst.
Archaeopyle: Precingular, Type P(3"" only), with free operculum.
Description:
The number of parasutural processes tends to increase in the lower Portlandian to upper Kimmeridgian and are often free distally. In these forms the trabeculum tends to become more irregular.
Holotype: Davey, 1982, pl.8, fig. 8-11; Riding and Davey, 1989, pl.1. fig.4
Locus typicus: West Abbey, Norfolk, England
Stratum typicum: Early Ryazanian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: Davey, 1982, p. 26-27
Diagnosis:
Shape: The pericyst, excluding processes, is ovoidal to noviform with very little dorso-ventral flattening.
Wall: The cyst wall is apparently two-layered, the two layers being closely appressed except where the periphragm alone forms the processes. The wall is of moderate thickness and the surface is smooth to little pitted.
Paratabulation: Parasutures are occasionally visible along the paracingulum and, more rarely, surrounding the parasulcal area.
Processes: These are parasutural in position. The gonal processes are trifurcate distally whereas the parasutural processes bifurcate distally. The furcations join with neighbouring ones to form a trabeculum which reflects the paratabulation. Distally the trabeculum bears small spines. The processes are longest on the dorsal hypocyst and decrease in size away from this region, being lowest on the ventral epicyst.
Archaeopyle: Precingular, Type P(3"" only), with free operculum.
Description:
The number of parasutural processes tends to increase in the lower Portlandian to upper Kimmeridgian and are often free distally. In these forms the trabeculum tends to become more irregular.