Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 9
... meet the commissure . The trigonal area is relatively narrow and almost flat . It is ornamented by finely beaded radial costellae , one of which corresponds to the escutcheon carina . There is no median groove to the area . The marginal ...
... meet the commissure . The trigonal area is relatively narrow and almost flat . It is ornamented by finely beaded radial costellae , one of which corresponds to the escutcheon carina . There is no median groove to the area . The marginal ...
Page 33
... meets the flanks at prominent anterolateral shoulders . The escutcheon is very broad , sunken , and extends almost ... meet the posteroventral margin at right angles . Occurrence Pterotrigonia ( ? Pterotrigonia ) knighti ( Pringle ) is ...
... meets the flanks at prominent anterolateral shoulders . The escutcheon is very broad , sunken , and extends almost ... meet the posteroventral margin at right angles . Occurrence Pterotrigonia ( ? Pterotrigonia ) knighti ( Pringle ) is ...
Page 37
... meet at the marginal carina in an anteriorly directed chevron . Beyond 15 mm from the umbo , the area is unornamented . Museum . In the nepionic stages the distinctly tuberculate flank costae are subconcen- tric . Later flank costae are ...
... meet at the marginal carina in an anteriorly directed chevron . Beyond 15 mm from the umbo , the area is unornamented . Museum . In the nepionic stages the distinctly tuberculate flank costae are subconcen- tric . Later flank costae are ...
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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