Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 29
... anterior , with moderately inturned , slightly opisthogyrous beaks . Valves moderately inflated anteriorly ( H / W = 0,40-0,57 ) . Anterior margin strongly convex , passing imperceptibly into the broad , gently convex ventral margin ...
... anterior , with moderately inturned , slightly opisthogyrous beaks . Valves moderately inflated anteriorly ( H / W = 0,40-0,57 ) . Anterior margin strongly convex , passing imperceptibly into the broad , gently convex ventral margin ...
Page 37
... anterior commissure . The anterior 12 or so costae are narrower than or as broad as the interspaces , finely but prominently tuberculate , and weakly curved until they reach the anterior face where they curve strongly upwards to meet the ...
... anterior commissure . The anterior 12 or so costae are narrower than or as broad as the interspaces , finely but prominently tuberculate , and weakly curved until they reach the anterior face where they curve strongly upwards to meet the ...
Page 39
... anterior set that curves markedly only on the anterior face to meet the com- missure at right angles , and a fine , crowded posterior set . The anterior costae are as wide as or narrower than the interspaces ; those closest to the umbo ...
... anterior set that curves markedly only on the anterior face to meet the com- missure at right angles , and a fine , crowded posterior set . The anterior costae are as wide as or narrower than the interspaces ; those closest to the umbo ...
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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