Rodzaj Mathilda Semper, 1865
Gatunek typowy Opis Protoconch hyperstrophic, diverging about 100–145° from teleoconch axis, smooth or, in some Mesozoic species, with adapical and abapical, axial folds. Teleoconch slender to broadly cone−shaped. Upper side with round to quadrangular, apertural lip, often slightly channeled at columella and under major spiral ribs of body whorl. First teleoconch whorl already with at least a subset of adult axial and spiral sculpture. Exposed primary sculpture on upper side consisting of 3 or more spiral ribs, 1 or 2 of main spiral ribs markedly more prominent than others. Number of spiral ribs increasing during ontogeny. At rib intersections, spiral ribs crossed by weaker axial ribs, threads or enhanced growth lines, usually with sculpture of rounded, more or less coarse, nodes. Base concave or slightly inflated, with several spiral threads or ribs, surrounding solid columella, or narrow umbilical chink, or funnel−shaped umbilicus. Synonimy Zasięg czasowy Mid Jurassic to Recent Literatura Kaim, A. 2004. The evolution of conch ontogeny in Mesozoic open sea gastropods. Palaeontologia Polonica 62, 3–183. Semper, O. 1865. Du genre Mathilda. Journal de Conchyliologie 13 (3), 328-341. |
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