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Pseudoceratium dettmanniae
Pseudoceratium dettmanniae Cookson and Hughes, 1964; Emendation: Harding and Hughes, 1990, p.312,314, as Endoceratium dettmanniae.
Now Endoceratium. Originally Pseudoceratium, subsequently (and now) Endoceratium. Helby, 1987 retained this species in Pseudoceratium; however, Lentin and Williams, 1989 retained it in Endoceratium Vozzhennikova, 1965.
Holotype: Cookson and Hughes, 1964, pl.7, fig.1
Locus typicus: Cambridge Greensand, Bradfortshire, England
Stratum typicum: Late Albian-early Cenomanian
Original diagnosis: Cookson and Hughes, 1964, p. 51
Shell approximately four-sided with a longish straight-sided apical horn and a short projection at each of the three angles. Indications of a +circular girdle occur in most specimens. The shell opens by the detachment of an apical segment along a straight or slightly oblique line. The surface of the shell is scabrate except for a relatively wide finely pitted band that encircles both dorsal and ventral surfaces. Transverse sections (cut by Dr. Mary Dettmann) have shown that the shell-membrane is two-layered, the two layers being in contact and traversed by elongated pits in the region of the pitted band mentioned above and widely separated from one another in the unpitted portions of the membrane.
Supplemental description: Davey, 1970, p. 354
One specimen attributable to this species was observed in the lowest Cenomanian sample from Fetcham Mill. The specimen possesses an apical archaeopyle with a slightly angular margin. The operculum is still attached and is conical in shape with a well developed apical horn. The main part of the shell has four sides of approximately equal length and bears an apical and two lateral horns. Two membranes of similar height (15-20 µm) are situated around the circumference of the shell. They are densely pitted and sometimes possess large circular perforations. The shell wall is very lightly granular. The cingulum is extremely faintly marked by an aligned concentration of granules.
Now Endoceratium. Originally Pseudoceratium, subsequently (and now) Endoceratium. Helby, 1987 retained this species in Pseudoceratium; however, Lentin and Williams, 1989 retained it in Endoceratium Vozzhennikova, 1965.
Holotype: Cookson and Hughes, 1964, pl.7, fig.1
Locus typicus: Cambridge Greensand, Bradfortshire, England
Stratum typicum: Late Albian-early Cenomanian
Original diagnosis: Cookson and Hughes, 1964, p. 51
Shell approximately four-sided with a longish straight-sided apical horn and a short projection at each of the three angles. Indications of a +circular girdle occur in most specimens. The shell opens by the detachment of an apical segment along a straight or slightly oblique line. The surface of the shell is scabrate except for a relatively wide finely pitted band that encircles both dorsal and ventral surfaces. Transverse sections (cut by Dr. Mary Dettmann) have shown that the shell-membrane is two-layered, the two layers being in contact and traversed by elongated pits in the region of the pitted band mentioned above and widely separated from one another in the unpitted portions of the membrane.
Supplemental description: Davey, 1970, p. 354
One specimen attributable to this species was observed in the lowest Cenomanian sample from Fetcham Mill. The specimen possesses an apical archaeopyle with a slightly angular margin. The operculum is still attached and is conical in shape with a well developed apical horn. The main part of the shell has four sides of approximately equal length and bears an apical and two lateral horns. Two membranes of similar height (15-20 µm) are situated around the circumference of the shell. They are densely pitted and sometimes possess large circular perforations. The shell wall is very lightly granular. The cingulum is extremely faintly marked by an aligned concentration of granules.