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Cyclonephelium ordinatum
Cyclonephelium ordinatum Williams and Downie, 1966
Now Glaphyrocysta. Originally Cyclonephelium, subsequently (and now) Glaphyrocysta.
Holotype: Williams and Downie 1966, pl.25, fig.3, text-fig.62
Locus typicus: London Clay, Enborne, England
Stratum typicum: Early Eocene
Translation Gocht, 1969: Geological Survey of Canada
Original diagnosis: Williams and Downie, 1966, p. 225-226
Thin walled central body with granular surface. Processes formed from periphragm and restricted to linear complexes regularly distributed on central body.
Reflected tabulation deduced form linear complexes of 4", 6"", 5""", 1p, 1"""". Processes slender, solid, taeniate, united half to two-thirds along their length by membranes or trabeculae. Processes distally unconnected and unequally bifurcate.
Dimensions: Holotype: diameter of central body 61x73 Ám. Length of processes up to 36 Ám. Observed range: diameter of central body 41-74 Ám, length of processes up to 40 Ám.
Original description: Williams and Davey, 1966, p. 226-227
This species is unusual in that it possesses processes restricted to the ambitus yet which are grouped into linear or sometimes arcuate complexes reflecting a dinoflagellate tabulation. The apical archaeopyle is nearly always developed and had a clear sulcal notch. The precingulars possess a variable number of processes, plates 1"", 2"", 4"" and 5"" having well-developed linear complexes, 3"" having a complex of varying extent, whilst 6"" can be devoid of processes.
The processes are not unlike those of Areoligera medusettiformis (O. Wetzel, 1933). The interconnnecting membrane sometimes extends to the base of the processes and, if so developed, is often fenestrate proximally. Distally the processes are bifurcate commonly with one fork longer than the other and recurved. Occasionally the processes are acuminate. Branching can occur distally to the interconnecting membrane or trabeculae.
Affinities:
Williams and Downie, 1966, p. 226: C. ordinatum differs from C. divaricum in the regular arrangement of the processes in liniear complexes and the larger overall size. It is included within the genus Cyclonephelium on account of the absence of processes from the mid-dorsal and ventral surface apart from those on the margin of the archaeopyle.
Gocht, 1969, p.58-60:
This species replaces Areoligera senonensis to a certain extent in the deep Early Eocene, and quickly becomes less frequent again above this range.
The body is delicate, weakly granulate, and always compressed. The processes are disposed meridionally around the main body leaving a central area open on the dorsal side and on the ventral side. They are finely branched, often artfully interconnected, and very variable in their shape and arrangement. The degree of differentiation in my material frequently exceeds that of the holotype from the Eocene London Clay. The archeopyle resembles that of Areoligera and Chiropteridium, at least as regards the 6 angled shape of the opening. C. ordinatum is linked with Chiropteridium also by the overall structure comprising two membranes, with the outer membrane forming the processes. The process bases, which I interpret as the lines of detachment of the membranes, extend rather far into the surfaces, and frequently farther on one side (the "dorsal") than on the other. The dorsal side also forms the process group which is displaced far inward over the antapex, and which is often striking because of its strongly differentiated, semicircular base. Williams and Downie interpret this group as postcingular 2""". Facing this group, also on the dorsal side, directly below the archeopyle, there is a group directed upward, without any counterpart on the ventral side (n.b.- longitudinal furrow). By analogy with Areoligera, this should represent a precingular plate; according to Downie and Williams, it is 3"". Beyond these relative positions, I would not risk following the further interpretation of the process groups advocated by Downie and Williams, partly because my specimens are compressed, and partly because of the wide variation which affects especially the lateral and apical processes. Sometimes a grouping of processes can be easily recognized, but difficult to interpret. The processes are apparently hollow. On some specimens they stand on slender shafts, widen halfway up into broad, bizarre surfaces, and narrow again distally into thin branches or spines. Balustrade formations and bridges connecting the ends of processes as in Cannosphaeropsis are common. Arcuate recesses are usually at the base and, in contrast to Chiropteridium, do not exhibit any membranous overlays. Hence, they represent the direct boundaries of the shafts of the processes. One specimen from sample 35 attests a deviant form with processes on the entire surface and strikingly low jags on the archeopyle margin.
Occurrence: Early Eocene.
Now Glaphyrocysta. Originally Cyclonephelium, subsequently (and now) Glaphyrocysta.
Holotype: Williams and Downie 1966, pl.25, fig.3, text-fig.62
Locus typicus: London Clay, Enborne, England
Stratum typicum: Early Eocene
Translation Gocht, 1969: Geological Survey of Canada
Original diagnosis: Williams and Downie, 1966, p. 225-226
Thin walled central body with granular surface. Processes formed from periphragm and restricted to linear complexes regularly distributed on central body.
Reflected tabulation deduced form linear complexes of 4", 6"", 5""", 1p, 1"""". Processes slender, solid, taeniate, united half to two-thirds along their length by membranes or trabeculae. Processes distally unconnected and unequally bifurcate.
Dimensions: Holotype: diameter of central body 61x73 Ám. Length of processes up to 36 Ám. Observed range: diameter of central body 41-74 Ám, length of processes up to 40 Ám.
Original description: Williams and Davey, 1966, p. 226-227
This species is unusual in that it possesses processes restricted to the ambitus yet which are grouped into linear or sometimes arcuate complexes reflecting a dinoflagellate tabulation. The apical archaeopyle is nearly always developed and had a clear sulcal notch. The precingulars possess a variable number of processes, plates 1"", 2"", 4"" and 5"" having well-developed linear complexes, 3"" having a complex of varying extent, whilst 6"" can be devoid of processes.
The processes are not unlike those of Areoligera medusettiformis (O. Wetzel, 1933). The interconnnecting membrane sometimes extends to the base of the processes and, if so developed, is often fenestrate proximally. Distally the processes are bifurcate commonly with one fork longer than the other and recurved. Occasionally the processes are acuminate. Branching can occur distally to the interconnecting membrane or trabeculae.
Affinities:
Williams and Downie, 1966, p. 226: C. ordinatum differs from C. divaricum in the regular arrangement of the processes in liniear complexes and the larger overall size. It is included within the genus Cyclonephelium on account of the absence of processes from the mid-dorsal and ventral surface apart from those on the margin of the archaeopyle.
Gocht, 1969, p.58-60:
This species replaces Areoligera senonensis to a certain extent in the deep Early Eocene, and quickly becomes less frequent again above this range.
The body is delicate, weakly granulate, and always compressed. The processes are disposed meridionally around the main body leaving a central area open on the dorsal side and on the ventral side. They are finely branched, often artfully interconnected, and very variable in their shape and arrangement. The degree of differentiation in my material frequently exceeds that of the holotype from the Eocene London Clay. The archeopyle resembles that of Areoligera and Chiropteridium, at least as regards the 6 angled shape of the opening. C. ordinatum is linked with Chiropteridium also by the overall structure comprising two membranes, with the outer membrane forming the processes. The process bases, which I interpret as the lines of detachment of the membranes, extend rather far into the surfaces, and frequently farther on one side (the "dorsal") than on the other. The dorsal side also forms the process group which is displaced far inward over the antapex, and which is often striking because of its strongly differentiated, semicircular base. Williams and Downie interpret this group as postcingular 2""". Facing this group, also on the dorsal side, directly below the archeopyle, there is a group directed upward, without any counterpart on the ventral side (n.b.- longitudinal furrow). By analogy with Areoligera, this should represent a precingular plate; according to Downie and Williams, it is 3"". Beyond these relative positions, I would not risk following the further interpretation of the process groups advocated by Downie and Williams, partly because my specimens are compressed, and partly because of the wide variation which affects especially the lateral and apical processes. Sometimes a grouping of processes can be easily recognized, but difficult to interpret. The processes are apparently hollow. On some specimens they stand on slender shafts, widen halfway up into broad, bizarre surfaces, and narrow again distally into thin branches or spines. Balustrade formations and bridges connecting the ends of processes as in Cannosphaeropsis are common. Arcuate recesses are usually at the base and, in contrast to Chiropteridium, do not exhibit any membranous overlays. Hence, they represent the direct boundaries of the shafts of the processes. One specimen from sample 35 attests a deviant form with processes on the entire surface and strikingly low jags on the archeopyle margin.
Occurrence: Early Eocene.