Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 25
... costellae , inner margin of shell crenulated posteroventrally ; 4 : = escutcheon with transverse costellae ; 5 = posteriorly produced to rostrate , often inflated anteriorly , in some with subterminal umbones , flank costae strongly ...
... costellae , inner margin of shell crenulated posteroventrally ; 4 : = escutcheon with transverse costellae ; 5 = posteriorly produced to rostrate , often inflated anteriorly , in some with subterminal umbones , flank costae strongly ...
Page 37
... costellae that become obsolete before reaching the commissure . In the 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 ...
... costellae that become obsolete before reaching the commissure . In the 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 ...
Page 39
... costellae along its outer margin , the inner margin being smooth . In some individuals the escutcheon is entirely ribbed or entirely smooth . Carinae are restricted to the nepionic stage . The area is narrow , bipartite , with oblique ...
... costellae along its outer margin , the inner margin being smooth . In some individuals the escutcheon is entirely ribbed or entirely smooth . Carinae are restricted to the nepionic stage . The area is narrow , bipartite , with oblique ...
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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