Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 13
... tubercles that increase in size posteriorly ; those of the escutcheon carina are elongated anteromedially and those of the marginal carina posteromedially . Each tubercle of the marginal carina corresponds with a flank costa . The area ...
... tubercles that increase in size posteriorly ; those of the escutcheon carina are elongated anteromedially and those of the marginal carina posteromedially . Each tubercle of the marginal carina corresponds with a flank costa . The area ...
Page 19
... tubercles tend to become elongated and may coalesce to form concen- tric growth rugae . In many individuals , the distal terminations of the ribs curve strongly to the anterior . Ornamentation does not extend on to the flattened ...
... tubercles tend to become elongated and may coalesce to form concen- tric growth rugae . In many individuals , the distal terminations of the ribs curve strongly to the anterior . Ornamentation does not extend on to the flattened ...
Page 24
... tubercles that vary in size and follow the growth striae . Posteriorly these tubercles are continuous with the growth rugae of the area . There is a very narrow lunule , about 40 per cent of the shell height . The ligament pit is ...
... tubercles that vary in size and follow the growth striae . Posteriorly these tubercles are continuous with the growth rugae of the area . There is a very narrow lunule , about 40 per cent of the shell height . The ligament pit 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