Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 29
... rounded , situated about 30 per cent of the shell length from the anterior , with moderately inturned , slightly opisthogyrous beaks . Valves moderately inflated anteriorly ( H / W = 0,40-0,57 ) . Anterior margin strongly convex ...
... rounded , situated about 30 per cent of the shell length from the anterior , with moderately inturned , slightly opisthogyrous beaks . Valves moderately inflated anteriorly ( H / W = 0,40-0,57 ) . Anterior margin strongly convex ...
Page 39
... rounded . The escutcheon is broad , deeply sunken , lanceolate , with weak oblique costellae along its outer margin , the inner margin being smooth . In some individuals the escutcheon is entirely ribbed or entirely smooth . Carinae are ...
... rounded . The escutcheon is broad , deeply sunken , lanceolate , with weak oblique costellae along its outer margin , the inner margin being smooth . In some individuals the escutcheon is entirely ribbed or entirely smooth . Carinae are ...
Page 43
... rounded to obliquely truncate ; escutcheon crossed by weak transverse costellae in nepionic stage , later smooth ; carinae generally restricted to nepionic stage ; area narrow , bipartite , smooth except in earliest growth stages ...
... rounded to obliquely truncate ; escutcheon crossed by weak transverse costellae in nepionic stage , later smooth ; carinae generally restricted to nepionic stage ; area narrow , bipartite , smooth except in earliest growth stages ...
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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