Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 9
... rib that thickens posteriorly and is crossed by growth lirae that give it a scaly corded appearance . The flanks are ... ribs terminate against the marginal carina of the right valve , but there is a narrow antecarinal sulcus to the left ...
... rib that thickens posteriorly and is crossed by growth lirae that give it a scaly corded appearance . The flanks are ... ribs terminate against the marginal carina of the right valve , but there is a narrow antecarinal sulcus to the left ...
Page 13
... ribs that pass with an inflexion across the marginal carina on to the area . The remaining flank costae are strongly oblique , posteriorly meeting the marginal carina at an angle of c . 30 ° . Except for the posterior few ribs , most ...
... ribs that pass with an inflexion across the marginal carina on to the area . The remaining flank costae are strongly oblique , posteriorly meeting the marginal carina at an angle of c . 30 ° . Except for the posterior few ribs , most ...
Page 29
... ribs running from the anterior commissure to the marginal carina , where they flex strongly forwards , forming an acute angle with the flank costae , to cross the area obliquely and pass weakly on to the outer part of the escutcheon ...
... ribs running from the anterior commissure to the marginal carina , where they flex strongly forwards , forming an acute angle with the flank costae , to cross the area obliquely and pass weakly on to the outer part of the escutcheon ...
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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