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Xylochoarion hacknessense
Xylochoarion hacknessense, Erkmen and Sarjeant, 1978, p. 404, 406
Holotype: Erkmen and Sarjeant, 1978, text-figs.1,5-6
Paratypes: Erkmen and Sarjeant, 1978
Locus typicus: Yorkshire, England
Stratum typicum: Callovian
Original diagnosis: Erkmen and Sarjeant, 1978:
A species of Xylochoarion having a broadly ellipsoidal to elongate ellipsoidal cyst, somewhat compressed dorsoventrally. One pole may hibit two asymmetrical outbulges of which one (that at left?) is much more pronounced than the other; or both poles may appear rounded. Spines numerous (c. 450 on a complete cyst), their length typically less than one quarter of the cyst breadth, though processes at the poles may approach that fraction. The form of the spines is highly variable. They may be slender or relatively thick, closed or open dorsally, sometimes showing basal thickening or union of two adjacent processes; they are only rarely simple, sometimes capitate, typically symmetrically or asymmetrically bifurcate, the tips of branches of adjacent processes sometimes being united. Cingulum rather narrow and indicated only by absence of processes.
Dimensions:
Holotype: length of cyst 78 µm, breadth 40 µm, length of processes 7-11 µm.
Paratype I: length of incomplete cyst 75 µm, breadth 57 µm, length of processes 8-12 µm.
Paratype II: length of incomplete cyst 51 µm, breadth 64 µm, length of processes 7-11 µm.
Paratype III: length of operculum 45 µm, breadth 41 µm, length of processes 7-10 µm.
Range of dimensions: length of operculum 31-55 µm (mean 39 µm), breadth 41-61 µm (mean 50.6 µm), length of incomplete cysts 61-75 µm (mean 70 µm), breadth 45-65 µm (mean 53 µm). Estimated range of measurements of complete cysts thus: length 78-82 µm (mean 80 µm), breadth 40-60 µm (mean 50 µm), length of processes 7-12 µm (mean 9.5 µm). Number of specimens measured: 17, of which only 2 were complete.
Holotype: Erkmen and Sarjeant, 1978, text-figs.1,5-6
Paratypes: Erkmen and Sarjeant, 1978
Locus typicus: Yorkshire, England
Stratum typicum: Callovian
Original diagnosis: Erkmen and Sarjeant, 1978:
A species of Xylochoarion having a broadly ellipsoidal to elongate ellipsoidal cyst, somewhat compressed dorsoventrally. One pole may hibit two asymmetrical outbulges of which one (that at left?) is much more pronounced than the other; or both poles may appear rounded. Spines numerous (c. 450 on a complete cyst), their length typically less than one quarter of the cyst breadth, though processes at the poles may approach that fraction. The form of the spines is highly variable. They may be slender or relatively thick, closed or open dorsally, sometimes showing basal thickening or union of two adjacent processes; they are only rarely simple, sometimes capitate, typically symmetrically or asymmetrically bifurcate, the tips of branches of adjacent processes sometimes being united. Cingulum rather narrow and indicated only by absence of processes.
Dimensions:
Holotype: length of cyst 78 µm, breadth 40 µm, length of processes 7-11 µm.
Paratype I: length of incomplete cyst 75 µm, breadth 57 µm, length of processes 8-12 µm.
Paratype II: length of incomplete cyst 51 µm, breadth 64 µm, length of processes 7-11 µm.
Paratype III: length of operculum 45 µm, breadth 41 µm, length of processes 7-10 µm.
Range of dimensions: length of operculum 31-55 µm (mean 39 µm), breadth 41-61 µm (mean 50.6 µm), length of incomplete cysts 61-75 µm (mean 70 µm), breadth 45-65 µm (mean 53 µm). Estimated range of measurements of complete cysts thus: length 78-82 µm (mean 80 µm), breadth 40-60 µm (mean 50 µm), length of processes 7-12 µm (mean 9.5 µm). Number of specimens measured: 17, of which only 2 were complete.