Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 9
... subconcentric costae that are slightly narrower than the interspaces on the posterior half of the shell . In maturity , the ribs flex slightly upwards anteriorly , becoming slightly oblique , crowded and broader than the interspaces ...
... subconcentric costae that are slightly narrower than the interspaces on the posterior half of the shell . In maturity , the ribs flex slightly upwards anteriorly , becoming slightly oblique , crowded and broader than the interspaces ...
Page 10
... subconcentric and entire but mostly strongly oblique and nodate , in derived forms may form chevrons . Discussion This superfamily comprises the families Frenguelliellidae ( Frenguelliellinae and Laevitrigoniinae ) with subconcentric ...
... subconcentric and entire but mostly strongly oblique and nodate , in derived forms may form chevrons . Discussion This superfamily comprises the families Frenguelliellidae ( Frenguelliellinae and Laevitrigoniinae ) with subconcentric ...
Page 11
... subconcentric flank costation is irregularly nodate and the antecarinal sulcus is very wide and shallow . The Myophorellinae are frenguelliellid descendants in which the flank costae are oblique in maturity and ornamented with ...
... subconcentric flank costation is irregularly nodate and the antecarinal sulcus is very wide and shallow . The Myophorellinae are frenguelliellid descendants in which the flank costae are oblique in maturity and ornamented with ...
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Common terms and phrases
Algoa Basin Anditrigonia antecarinal sulcus anterior commissure anterolateral shoulder anteroventrally Apiotrigoniinae Bivalvia broad chevrons coarse commissure comprises convex Cooper Cretaceous Description Shell Diagnosis elongate escutcheon carina faunas finely crenulated flank costae flank ornament genus growth rugae growth striae Hauterivian Hoepen holotype inflated anteriorly interspaces Iotrigonia irregular Kobayashi kraussi Kitchin lanceolate large maximum length Lateral view lectotype left valve longitudinal groove Megatrigoniacea moderately Myophorella Myophoriidae Nakano neotype nepionic stages Neumayr nodate Nototrigoniinae opisthogyrous beaks Paranditrigonia paratypes persisting to maturity phyletic Port Elizabeth Museum posterior set posterodorsal margin Poulton Pterotrigonia radial costellae radial ornament Rennie respiratory margin Reyes ribs right valve rostrate shallowly concave shell length Skwarko smooth South African Museum Steinmanella herzogi Goldfuss straight strongly oblique subconcentric subfamily Sundays River Superfamily synonymy Tashiro Tithonian transverse costellae transverse ornament Trigonia Trigoniacea Trigoniinae trigonioid tubercles Type species Upper Valanginian V-shaped Valanginian vau Sharpe ventral margin ventricosa Krauss Yaadia