Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 9
... convex anterior margin . The ventral margin is broadly convex and the moder- ately short respiratory margin obliquely truncate . The escutcheon is lanceolate , slightly more than half the shell length , and is ornamented with radial ...
... convex anterior margin . The ventral margin is broadly convex and the moder- ately short respiratory margin obliquely truncate . The escutcheon is lanceolate , slightly more than half the shell length , and is ornamented with radial ...
Page 27
... convex ; escutcheon carina lacking , marginal carina restricted to nepionic stages ; bipartite area initially with concentric ribs , later smooth ; flank costae primitively subconcentric anteriorly and subvertical and crowded pos ...
... convex ; escutcheon carina lacking , marginal carina restricted to nepionic stages ; bipartite area initially with concentric ribs , later smooth ; flank costae primitively subconcentric anteriorly and subvertical and crowded pos ...
Page 29
... convex , passing imperceptibly into the broad , gently convex ventral margin ; the posterodorsal margin is shallowly concave and the respiratory margin rounded . The very elongate , lanceolate escutcheon is sunken and smooth . There is ...
... convex , passing imperceptibly into the broad , gently convex ventral margin ; the posterodorsal margin is shallowly concave and the respiratory margin rounded . The very elongate , lanceolate escutcheon is sunken and smooth . There is ...
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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