Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 7
... umbones well developed ; carinae and radial costellae to area persisting to maturity ; marginal carina corded ; antecari- nal groove variable , often restricted to left valve . Genus Trigonia Brugière , 1789 Type species . Venus sulcata ...
... umbones well developed ; carinae and radial costellae to area persisting to maturity ; marginal carina corded ; antecari- nal groove variable , often restricted to left valve . Genus Trigonia Brugière , 1789 Type species . Venus sulcata ...
Page 25
... umbones are generally not subterminal , area rela- tively narrow with concentric ornament in nepionic stages later smooth , flank costae subconcentric ; 2 beyond nepionic stages flank costae V - shaped , with tendency to form nodes at ...
... umbones are generally not subterminal , area rela- tively narrow with concentric ornament in nepionic stages later smooth , flank costae subconcentric ; 2 beyond nepionic stages flank costae V - shaped , with tendency to form nodes at ...
Page 29
... Umbones fairly prominent , rounded , situated about 30 per cent of the shell length from the anterior , with moderately inturned , slightly opisthogyrous beaks . Valves moderately inflated anteriorly ( H / W = 0,40-0,57 ) . Anterior ...
... Umbones fairly prominent , rounded , situated about 30 per cent of the shell length from the anterior , with moderately inturned , slightly opisthogyrous beaks . Valves moderately inflated anteriorly ( H / W = 0,40-0,57 ) . Anterior ...
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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