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Impletosphaeridium tribuliferum
Cleistosphaeridium tribuliferum (Sarjeant, 1962) Islam, 1993
NOW Downiesphaeridium. Originally Baltisphaeridium (Appendix A), subsequently Cleistosphaeridium, thirdly Cleistosphaeridium?, fourthly Impletosphaeridium, fifthly (and now) Downiesphaeridium.
Holotype: Sarjeant, 1962a, pl.70, fig.4; Fauconnier and Masure, 2004, pl.23, fig.11.
Age: Oxfordian.
Translation Courtinat, 1989: LPP
Diagnosis: Sarjeant 1962a, p. 487-488: Baltisphaeridium tribuliferum
A species of Baltisphaeridium having an ovoid shell bearing widely spaced processes, attached proximally by root-like extensions on the shell surface and tapering somewhat distally, branching at a constant distance from the shell surface into bi-, tri- or quadri-furcations of variable length and attitude.
Dimensions of type: Overall: long diameter 59 Á, short diameter 54 Á. Shell long diameter 33Á, short meter 25.5 Á. Range of dimensions. Overall: long diameters 53-62 Á, short diameters 48-58 Á
Description: Sarjeant 1962a, p. 487-488: Baltisphaeridium tribuliferum
Shell smooth, without granulation or punctation, varying in hue from yellowish to quite colourless. The spines are hollow but appear not to open directly into the shell's interior. I'ney are of very variable form, never simple but l-aving two to four branches of varying length: the branches appear flexible and may be directed oulward from, or inward towards, the shell ,urface or may be roughly parallel to it (text-fig. 7). The branches are closed at their tips. The spines are widely spaced: the number present is between about forty-five and sixty; in length they exceed half the long diameter.
Remarks: Sarjeant 1962a, p. 487-488
Baltisphaericlium tribuliferum differs from all described species of this genus in its combination of form, and proportionate length, of processes with shell shape. The forms from the Lower Oxfordian of France, described by Deflandre as Hystrichosphaeridium cf. intermedium (1938), are probably attributable to this species, as also is the form from the Bathonian of France, described under this name by Valensi (1953). This species is present in low numbers at three Melton horizons and has also been noted from all three horizons of the Yorkshire Oxford Clay (see above) and from the Lower Calcareous Grit and Hambleton Oolite of Filey Brigg, Yorkshire.
Remark: Courtinat, 1989, p.167: Cleistosphaeridium tribuliferum
This species has characteristics resembling those of Hystrichosphaeridium petilum and Surculosphaeridium cribrotubiferum in the nature of distal process ends. The latter two species are distinguished, the first by the tubiform processes, the second by the solid processes. In this characteristic, C. tribuliferum resembles H. petilum. Although no specimen permitted such an observation, it seems probable that, considering their number (between 22 and 26), the processes are intratabular. If this would be confirmed, H. petilum would be a new synonym of C. tribuliferum.
NOW Downiesphaeridium. Originally Baltisphaeridium (Appendix A), subsequently Cleistosphaeridium, thirdly Cleistosphaeridium?, fourthly Impletosphaeridium, fifthly (and now) Downiesphaeridium.
Holotype: Sarjeant, 1962a, pl.70, fig.4; Fauconnier and Masure, 2004, pl.23, fig.11.
Age: Oxfordian.
Translation Courtinat, 1989: LPP
Diagnosis: Sarjeant 1962a, p. 487-488: Baltisphaeridium tribuliferum
A species of Baltisphaeridium having an ovoid shell bearing widely spaced processes, attached proximally by root-like extensions on the shell surface and tapering somewhat distally, branching at a constant distance from the shell surface into bi-, tri- or quadri-furcations of variable length and attitude.
Dimensions of type: Overall: long diameter 59 Á, short diameter 54 Á. Shell long diameter 33Á, short meter 25.5 Á. Range of dimensions. Overall: long diameters 53-62 Á, short diameters 48-58 Á
Description: Sarjeant 1962a, p. 487-488: Baltisphaeridium tribuliferum
Shell smooth, without granulation or punctation, varying in hue from yellowish to quite colourless. The spines are hollow but appear not to open directly into the shell's interior. I'ney are of very variable form, never simple but l-aving two to four branches of varying length: the branches appear flexible and may be directed oulward from, or inward towards, the shell ,urface or may be roughly parallel to it (text-fig. 7). The branches are closed at their tips. The spines are widely spaced: the number present is between about forty-five and sixty; in length they exceed half the long diameter.
Remarks: Sarjeant 1962a, p. 487-488
Baltisphaericlium tribuliferum differs from all described species of this genus in its combination of form, and proportionate length, of processes with shell shape. The forms from the Lower Oxfordian of France, described by Deflandre as Hystrichosphaeridium cf. intermedium (1938), are probably attributable to this species, as also is the form from the Bathonian of France, described under this name by Valensi (1953). This species is present in low numbers at three Melton horizons and has also been noted from all three horizons of the Yorkshire Oxford Clay (see above) and from the Lower Calcareous Grit and Hambleton Oolite of Filey Brigg, Yorkshire.
Remark: Courtinat, 1989, p.167: Cleistosphaeridium tribuliferum
This species has characteristics resembling those of Hystrichosphaeridium petilum and Surculosphaeridium cribrotubiferum in the nature of distal process ends. The latter two species are distinguished, the first by the tubiform processes, the second by the solid processes. In this characteristic, C. tribuliferum resembles H. petilum. Although no specimen permitted such an observation, it seems probable that, considering their number (between 22 and 26), the processes are intratabular. If this would be confirmed, H. petilum would be a new synonym of C. tribuliferum.