Back
Gonyaulacysta exilicristata
Gonyaulacysta exilicristata Davey, 1969
Now Cribroperidinium. Originally Gonyaulacysta, subsequently (and now) Cribroperidinium.
Holotype: Davey, 1969, pl.1, fig.1; text-figs.9A-B; Jan du Chêne et al., 1986, pl.26, figs.1-4
Locus typicus: Fetcham Mill, England
Stratum typicum: Cenomanian
Original diagnosis: Davey, 1969, p. 121
Shell subspherical; moderately well developed apical horn. Shell wall thick, finely but densely granular. Reflected tabulation 3", Ia, 6", 6c, 6""" (--7"""?), 1p, 1"""". Plate boundaries marked by low, poorly defined crests which sometimes form small spines at crestal nodes. Cingulum narrow, weakly laevorotatory; sulcus of moderate width, widening slightly posteriorly.
Original description: Davey, 1969, p. 121
The shell wall measures between 2 and 3 µm in thickness, the endophragm being approximately twice as thick as the periphragm. The latter forms the apical horn which is triangular in cross-section due to the sutural ridges which delimit the apical plates extending along it. Lines of ornamentation, sometimes similar to the sutural crests, are present on some of the plates, particularly those in the postcingular series. Occasionally it appears that plate 4""" is subdivided by a low ridge so giving seven postcingular plates.
The cingulum is fairly narrow (3-4 µm) and only slightly laevo-rotatory. The sulcus often possesses a posterior ventral plate. In the medial-posterior part of the furrow there is usually an elongate depression, as seeninthe holotype (Fig. gA). A precingular archaeopyle is typically present.
Now Cribroperidinium. Originally Gonyaulacysta, subsequently (and now) Cribroperidinium.
Holotype: Davey, 1969, pl.1, fig.1; text-figs.9A-B; Jan du Chêne et al., 1986, pl.26, figs.1-4
Locus typicus: Fetcham Mill, England
Stratum typicum: Cenomanian
Original diagnosis: Davey, 1969, p. 121
Shell subspherical; moderately well developed apical horn. Shell wall thick, finely but densely granular. Reflected tabulation 3", Ia, 6", 6c, 6""" (--7"""?), 1p, 1"""". Plate boundaries marked by low, poorly defined crests which sometimes form small spines at crestal nodes. Cingulum narrow, weakly laevorotatory; sulcus of moderate width, widening slightly posteriorly.
Original description: Davey, 1969, p. 121
The shell wall measures between 2 and 3 µm in thickness, the endophragm being approximately twice as thick as the periphragm. The latter forms the apical horn which is triangular in cross-section due to the sutural ridges which delimit the apical plates extending along it. Lines of ornamentation, sometimes similar to the sutural crests, are present on some of the plates, particularly those in the postcingular series. Occasionally it appears that plate 4""" is subdivided by a low ridge so giving seven postcingular plates.
The cingulum is fairly narrow (3-4 µm) and only slightly laevo-rotatory. The sulcus often possesses a posterior ventral plate. In the medial-posterior part of the furrow there is usually an elongate depression, as seeninthe holotype (Fig. gA). A precingular archaeopyle is typically present.