Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 9
... slightly more than half the shell length , and is ornamented with radial rows of fine tubercles that , on D1876 ... slightly narrower than the interspaces on the posterior half of the shell . In maturity , the ribs flex slightly upwards ...
... slightly more than half the shell length , and is ornamented with radial rows of fine tubercles that , on D1876 ... slightly narrower than the interspaces on the posterior half of the shell . In maturity , the ribs flex slightly upwards ...
Page 24
... slightly opisthogyrous beaks . The ventral margin is very long , weakly convex , and the broad respiratory margin subtruncate . The escutcheon is fairly narrow , and about two - thirds the length of the shell . It is ornamented by ...
... slightly opisthogyrous beaks . The ventral margin is very long , weakly convex , and the broad respiratory margin subtruncate . The escutcheon is fairly narrow , and about two - thirds the length of the shell . It is ornamented by ...
Page 37
... slightly opisthogyrous beaks . Anterior margin broadly convex , flattish , passing into the very broad , gently convex ventral margin . The postero- dorsal margin is shallowly concave , and the respiratory margin subtruncate with a ...
... slightly opisthogyrous beaks . Anterior margin broadly convex , flattish , passing into the very broad , gently convex ventral margin . The postero- dorsal margin is shallowly concave , and the respiratory margin subtruncate with a ...
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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