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Hystrichosphaerina paracalatha
Hystrichosphaerina paracalatha (Sarjeant, 1960) Duxbury, 1980
Now Polystephanephorus . Originally Polystephanosphaera, subsequently (and now) Polystephanephorus, thirdly Hystrichosphaerina. Lentin and Williams, 1981, retained this species in Polystephanephorus Sarjeant, 1961.
Holotype: Sarjeant 1960, pl.6, fig.4, text-fig.3b; Stancliffe and Sarjeant, 1990, pl.2, figs.2,3,5; text-fig.2
Locus typicus: Webb, Major and Company"s Crook Hill brickyard, 2 mile S of Chickerell Church, near Weymouth, England
Stratum typicum: Middle Callovian
Original diagnosis: Sarjeant, 1960, p. 143: Polystephanosphaera paracalathus
A species of Polystephanosphaera having processes of variable thickness, sometimes bifurcating, sometimes simple, most often widening considerably at a constant distance from the shell surfacc. All proccsses of each group bend outwards from their point of origin and are comlected together at their tips by a trabecula, each group of processes thus having thc aipect of a skeletal vase with a bell mouth.
Original description: Sarjeant, 1960, p. 143: Polystephanosphaera paracalathus
As in P. calatus, the trabecula linking each group of processes at their tips appears to arise from the bifurcation of a single process in each group and the lateral extension of its branches to link up with the tips of other processes.
In some cases, adjacent groups of processes are connected by a single trabecula: these linking trabeculae have, hanging from them at about mid-point between process groups, a membraneous filament.
Dimensions. Type: overall diameter 92 Ám, diameter of shell 40 Ám, processes 26 Ám in length. Range: overall diameter 85 to 100 Ám.
Emended diagnosis: Stancliffe and Sarjeant, 1990, p. 206
Body spherical to subspherical, with a smooth to granular autophragm. Five to nine processes are arranged in intratabular clusters which, when viewed laterally, are seen to flare distally. Paratabulation probably ?4", 5", 0c, 6""", 1"""", 0s. Processes thin, thickening distally, solid with occasional medial branching; only one order of branching being developed. Processes terminate in a ring trabecula of variable thickness, which originates from the bifurcation of one process. Each cluster can develop inter-cluster trabeculae. These may join between clusters to form a triple junction and can have dagger-like extensions on the proximal side, usually halfway between adjacent clusters. No cingular or sulcal processes are developed. The archeopyle is apical, type (tA), with a well developed sulcal notch.
Affinities:
Sarjeant, 1960, p. 143-144: Polystephanosphaera paracalathus
In the arrangement of processes and their linkage, this species differs from all the other described species and resembles Polystephanosphaera ealathlls, of the Oxford Clay of Yorkshire (1960). However, the more robust form of the processes and their broadening at the point of linkage, and the bell-mouthed form of the process groups afford major differences from the species. The processes of Polystephanosphaera urnaformis (Cookson, 1953) differ in that they are coalescent at their base as well as at their tip.
Now Polystephanephorus . Originally Polystephanosphaera, subsequently (and now) Polystephanephorus, thirdly Hystrichosphaerina. Lentin and Williams, 1981, retained this species in Polystephanephorus Sarjeant, 1961.
Holotype: Sarjeant 1960, pl.6, fig.4, text-fig.3b; Stancliffe and Sarjeant, 1990, pl.2, figs.2,3,5; text-fig.2
Locus typicus: Webb, Major and Company"s Crook Hill brickyard, 2 mile S of Chickerell Church, near Weymouth, England
Stratum typicum: Middle Callovian
Original diagnosis: Sarjeant, 1960, p. 143: Polystephanosphaera paracalathus
A species of Polystephanosphaera having processes of variable thickness, sometimes bifurcating, sometimes simple, most often widening considerably at a constant distance from the shell surfacc. All proccsses of each group bend outwards from their point of origin and are comlected together at their tips by a trabecula, each group of processes thus having thc aipect of a skeletal vase with a bell mouth.
Original description: Sarjeant, 1960, p. 143: Polystephanosphaera paracalathus
As in P. calatus, the trabecula linking each group of processes at their tips appears to arise from the bifurcation of a single process in each group and the lateral extension of its branches to link up with the tips of other processes.
In some cases, adjacent groups of processes are connected by a single trabecula: these linking trabeculae have, hanging from them at about mid-point between process groups, a membraneous filament.
Dimensions. Type: overall diameter 92 Ám, diameter of shell 40 Ám, processes 26 Ám in length. Range: overall diameter 85 to 100 Ám.
Emended diagnosis: Stancliffe and Sarjeant, 1990, p. 206
Body spherical to subspherical, with a smooth to granular autophragm. Five to nine processes are arranged in intratabular clusters which, when viewed laterally, are seen to flare distally. Paratabulation probably ?4", 5", 0c, 6""", 1"""", 0s. Processes thin, thickening distally, solid with occasional medial branching; only one order of branching being developed. Processes terminate in a ring trabecula of variable thickness, which originates from the bifurcation of one process. Each cluster can develop inter-cluster trabeculae. These may join between clusters to form a triple junction and can have dagger-like extensions on the proximal side, usually halfway between adjacent clusters. No cingular or sulcal processes are developed. The archeopyle is apical, type (tA), with a well developed sulcal notch.
Affinities:
Sarjeant, 1960, p. 143-144: Polystephanosphaera paracalathus
In the arrangement of processes and their linkage, this species differs from all the other described species and resembles Polystephanosphaera ealathlls, of the Oxford Clay of Yorkshire (1960). However, the more robust form of the processes and their broadening at the point of linkage, and the bell-mouthed form of the process groups afford major differences from the species. The processes of Polystephanosphaera urnaformis (Cookson, 1953) differ in that they are coalescent at their base as well as at their tip.