Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 25
... nepionic stages , marginal carina often restricted to umbonal region , anteriorly produced so that umbones are generally not subterminal , area rela- tively narrow with concentric ornament in nepionic stages later smooth , flank costae ...
... nepionic stages , marginal carina often restricted to umbonal region , anteriorly produced so that umbones are generally not subterminal , area rela- tively narrow with concentric ornament in nepionic stages later smooth , flank costae ...
Page 37
... nepionic stages , the costellae of the escutcheon extend to the median longi- tudinal groove of the area , giving the inner area a beaded appearance for up to 15 mm from the beak . A beaded marginal carina may extend for the same dis ...
... nepionic stages , the costellae of the escutcheon extend to the median longi- tudinal groove of the area , giving the inner area a beaded appearance for up to 15 mm from the beak . A beaded marginal carina may extend for the same dis ...
Page 43
... nepionic stage , later smooth ; carinae generally restricted to nepionic stage ; area narrow , bipartite , smooth except in earliest growth stages ; flanks with generally fine sub- concentric costae anteriorly meeting fewer , broader ...
... nepionic stage , later smooth ; carinae generally restricted to nepionic stage ; area narrow , bipartite , smooth except in earliest growth stages ; flanks with generally fine sub- concentric costae anteriorly meeting fewer , broader ...
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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