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Maduradinium
From Williams et al., 2017:
[Maduradinium, Cookson and Eisenack 1970a, p. 150
Type species: Maduradinium pentagonum, Cookson and Eisenack, 1970a (pl.10, fig.13)]
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Original description: [Cookson and Eisenack, 1970]:
Description:
Shell five-sided to nearly circular in outline with a readily detachable apical horn and one or two antapical projections. Girdle relatively ventral furrow. The archaeopyle is relatively large, precingular, six-sided with a straight to somewhat rounded outline.
Surface of shell finely granular, typically with scattered patches of more or less strongly developed, closely arranged thickings, especially in the vicinity of
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Stover and Evitt, 1978, p. 233:
Comment:
Cookson & Eisenack (1970) apparently consider the presence of "a readily detachable apical horn" as significant and report that, of the eight specimens studied, apical horns are lost in seven of them. The relative merit and taxonomic value of this condition is uncertain, but it seems dubious as a generic feature. The archeopyle is described as precingular and six-sided; judging from the illustrations, it appears more likely that the archeopyle is intercalary, which is compatible with its six-sided outline. If Maduradinium has an intercalary archeopyle, then the difference between Maduradinium and Lejeunia would be slight and suppression of the former should follow.
[Maduradinium, Cookson and Eisenack 1970a, p. 150
Type species: Maduradinium pentagonum, Cookson and Eisenack, 1970a (pl.10, fig.13)]
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Original description: [Cookson and Eisenack, 1970]:
Description:
Shell five-sided to nearly circular in outline with a readily detachable apical horn and one or two antapical projections. Girdle relatively ventral furrow. The archaeopyle is relatively large, precingular, six-sided with a straight to somewhat rounded outline.
Surface of shell finely granular, typically with scattered patches of more or less strongly developed, closely arranged thickings, especially in the vicinity of
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Stover and Evitt, 1978, p. 233:
Comment:
Cookson & Eisenack (1970) apparently consider the presence of "a readily detachable apical horn" as significant and report that, of the eight specimens studied, apical horns are lost in seven of them. The relative merit and taxonomic value of this condition is uncertain, but it seems dubious as a generic feature. The archeopyle is described as precingular and six-sided; judging from the illustrations, it appears more likely that the archeopyle is intercalary, which is compatible with its six-sided outline. If Maduradinium has an intercalary archeopyle, then the difference between Maduradinium and Lejeunia would be slight and suppression of the former should follow.