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Gonyaulacysta delicata
Gonyaulacysta delicata Davey, 1969
Now Leptodinium?. Originally Gonyaulacysta, subsequently Leptodinium, thirdly (and now) Leptodinium?.
Holotype: Davey, 1969, pl.1, fig.7, text-figs. 10A-B; Jan du Chene et al., 1986, pl.75, figs.1-3.
Paratype: Davey, 1969, pl.1, fig.8
Locus typicus: Saskatchewan, Canada
Stratum typicum: Cenomanian
Original description: Davey, 1969, p. 132
Shell subspherical, epitract and hypotract of similar size. Shell wall thin, smooth. Apical horn absent, there being a small circular apical plate in this position surrounded by three large apical plates. Reflected tabulation 4", 1a, 6", 6c, 6""", 1p, 1"""". Plate boundaries well defined by low crests. Cingulum wide, strongly laevo-rotatory; sulcus broad.
Original description: Davey, 1969, p. 123
The shell wall is very thin (less than 0.5µm thick) and only attains a thickness of 0.5 µm when forming the plate boundaries. Due to the thinness of the shell wall specimens are easily distorted. The tabulation has, however, been formulated after the examination of a number of specimens. Anteriorly three apical plates (2", 3" and 4") abutt against a small circular plate, plate 1", which is in the position normally occupied by the apical horn. The precingular and postcingular series of plates are large and more or less pentagonal. Plate 3"" is always lost in archaeopyle formation. The first postcingular plate is elongate and has a poorly defined sulcal border. The cingulum is wide (4 to 7 µm) and tends to be constricted at the cingular plate boundaries. The sulcus is broad and widens slightly towards the posterior. The anterior end of the sulcus has a flat margin from which arise plates 1" and 1a. At the posterior end of the sulcus there may be developed a posterior ventral plate.
Now Leptodinium?. Originally Gonyaulacysta, subsequently Leptodinium, thirdly (and now) Leptodinium?.
Holotype: Davey, 1969, pl.1, fig.7, text-figs. 10A-B; Jan du Chene et al., 1986, pl.75, figs.1-3.
Paratype: Davey, 1969, pl.1, fig.8
Locus typicus: Saskatchewan, Canada
Stratum typicum: Cenomanian
Original description: Davey, 1969, p. 132
Shell subspherical, epitract and hypotract of similar size. Shell wall thin, smooth. Apical horn absent, there being a small circular apical plate in this position surrounded by three large apical plates. Reflected tabulation 4", 1a, 6", 6c, 6""", 1p, 1"""". Plate boundaries well defined by low crests. Cingulum wide, strongly laevo-rotatory; sulcus broad.
Original description: Davey, 1969, p. 123
The shell wall is very thin (less than 0.5µm thick) and only attains a thickness of 0.5 µm when forming the plate boundaries. Due to the thinness of the shell wall specimens are easily distorted. The tabulation has, however, been formulated after the examination of a number of specimens. Anteriorly three apical plates (2", 3" and 4") abutt against a small circular plate, plate 1", which is in the position normally occupied by the apical horn. The precingular and postcingular series of plates are large and more or less pentagonal. Plate 3"" is always lost in archaeopyle formation. The first postcingular plate is elongate and has a poorly defined sulcal border. The cingulum is wide (4 to 7 µm) and tends to be constricted at the cingular plate boundaries. The sulcus is broad and widens slightly towards the posterior. The anterior end of the sulcus has a flat margin from which arise plates 1" and 1a. At the posterior end of the sulcus there may be developed a posterior ventral plate.