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Hystrichosphaera crassipellis
Hystrichosphaera crassipellis Deflandre and Cookson, 1955
Now Achomosphaera. Originally Hystrichosphaera, subsequently Spiniferites, thirdly (and now) Achomosphaera.
Possible tax. sr. synonym of Achomosphaera sagena Davey and Williams, 1966, according to May, 1980. Lentin and Williams, 1981, retained Achomosphaera sagena as a separate species.
Hystrichosphaera crassipellis was a nomen nudum in Deflandre and Cookson, 1954.
Holotype: Deflandre and Cookson, 1955, pl. 6, figs.2-3
Locus typicus: Victoria, Australia
Stratum typicum: Early Eocene
Translation Gocht, 1969: Geological Survey of Canada
Original descrpition: Deflandre and Cookson, 1955, p. 265
Shell globular, almost sphaerical, with an unusually thick membrane; lines seperating the fields sometimes rather indistinct, sometimes aliform; fields polygonal, the elongated equatorial series present. Processes appearently fragile, formed of a thin transparent membrane, forked or more or less divided at the apex. Surface of shell membrane ornamented with a clearly marked reticulum, the meshes being about 1.5-2 Ám. In certain examples the mesh is finer and closer. The membrane is nonhomogeneous and shows a fibrillar structure.
Supplemental descripition: Davey and Williams, 1960, p. 40
H. crassipellis possesses a thick central body wall (up to 6.5 Ám in thickness) which is coarsely reticulate. The reticulation is rather irregular having from almost circular to polygonal fields. The processes are gonal, subconical in shape and commonly bifurcate with bifurcating extremities. The paired cingular processes are joined by a membrane. The crests are proximal, reasonably well developed and may be reticulate, especially at their outer edges. H. cvassipellis is a rare species occurring throughout the Cenomanian of England.
Gocht, 1969, p.33:
Hystrichosphaera cf. crassipellis Deflandre and Cookson, 1954
This form will be discussed further in connection with Achomosphaera cf. sagena.
The very thick-walled inner membrane is covered by an outer membrane with cingulum and ridged field boundaries. The processes are quite slender and thin, but not as fragile as the authors report for H. crassipellis. Also the distinctly reticulate surface sculpture is absent. The lists which join the somewhat expanded bases of the processes are not always distinct, so that there are transitional forms towards Achomosphaera cf. sagena, which also sometimes shows a cingulum and field boundaries. The archeopyle is trapezoidal and similar to those of other Hystrichosphaera species. A deviant specimen with perforated outer membrane and processes corresponds with the find of dubious determination figured by Gerlach, 1961.
Measurements: maximal extension 119-131 µm, inner body diameter 65-78 µm.
Occurrence: Early Eocene.
Now Achomosphaera. Originally Hystrichosphaera, subsequently Spiniferites, thirdly (and now) Achomosphaera.
Possible tax. sr. synonym of Achomosphaera sagena Davey and Williams, 1966, according to May, 1980. Lentin and Williams, 1981, retained Achomosphaera sagena as a separate species.
Hystrichosphaera crassipellis was a nomen nudum in Deflandre and Cookson, 1954.
Holotype: Deflandre and Cookson, 1955, pl. 6, figs.2-3
Locus typicus: Victoria, Australia
Stratum typicum: Early Eocene
Translation Gocht, 1969: Geological Survey of Canada
Original descrpition: Deflandre and Cookson, 1955, p. 265
Shell globular, almost sphaerical, with an unusually thick membrane; lines seperating the fields sometimes rather indistinct, sometimes aliform; fields polygonal, the elongated equatorial series present. Processes appearently fragile, formed of a thin transparent membrane, forked or more or less divided at the apex. Surface of shell membrane ornamented with a clearly marked reticulum, the meshes being about 1.5-2 Ám. In certain examples the mesh is finer and closer. The membrane is nonhomogeneous and shows a fibrillar structure.
Supplemental descripition: Davey and Williams, 1960, p. 40
H. crassipellis possesses a thick central body wall (up to 6.5 Ám in thickness) which is coarsely reticulate. The reticulation is rather irregular having from almost circular to polygonal fields. The processes are gonal, subconical in shape and commonly bifurcate with bifurcating extremities. The paired cingular processes are joined by a membrane. The crests are proximal, reasonably well developed and may be reticulate, especially at their outer edges. H. cvassipellis is a rare species occurring throughout the Cenomanian of England.
Gocht, 1969, p.33:
Hystrichosphaera cf. crassipellis Deflandre and Cookson, 1954
This form will be discussed further in connection with Achomosphaera cf. sagena.
The very thick-walled inner membrane is covered by an outer membrane with cingulum and ridged field boundaries. The processes are quite slender and thin, but not as fragile as the authors report for H. crassipellis. Also the distinctly reticulate surface sculpture is absent. The lists which join the somewhat expanded bases of the processes are not always distinct, so that there are transitional forms towards Achomosphaera cf. sagena, which also sometimes shows a cingulum and field boundaries. The archeopyle is trapezoidal and similar to those of other Hystrichosphaera species. A deviant specimen with perforated outer membrane and processes corresponds with the find of dubious determination figured by Gerlach, 1961.
Measurements: maximal extension 119-131 µm, inner body diameter 65-78 µm.
Occurrence: Early Eocene.