Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . posed in the umbilical seam. Increase in diameter is rapid. The costal whorl section on the phragmocone is distinctly quadrate,sometimes even wider than high in early stages, whereas the intercostal sectionis more rounded (Figs 106B, 108). Towards the later part of the phragmoconethe whorl section becomes more rounded (Fig. 107B), higher than wide, andeventually dome-shaped on the body chamber (Fig. 105A). Ornament on thephragmocone consists of prominent ribs bearing very strong tubercles andseparated by wider intersp
Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . posed in the umbilical seam. Increase in diameter is rapid. The costal whorl section on the phragmocone is distinctly quadrate,sometimes even wider than high in early stages, whereas the intercostal sectionis more rounded (Figs 106B, 108). Towards the later part of the phragmoconethe whorl section becomes more rounded (Fig. 107B), higher than wide, andeventually dome-shaped on the body chamber (Fig. 105A). Ornament on thephragmocone consists of prominent ribs bearing very strong tubercles andseparated by wider interspaces. The umbilical (1) tubercles are conical toradially elongated, pointed slightly inwards and with bases extending alittle distance down the umbilical wall. The lateral (2) tubercles are situatedat midflank or on the dorsal third of the flanks and are conical to clavate, andseparated from the umbilical tubercles by a depression on the ribs. The sub-marginal (3), marginal (4), and external (5) tubercles are situated closer to each CRETACEOUS FAUNAS FROM SOUTH AFRICA 139. Fig. 104. Texanites quadrangulatus CoUignon, 1966. SAS-A2580. X 0,58. Other than the umbilical and lateral ones throughout ontogeny, but especiallyon the inner whorls. Here the submarginal tubercles may be tremendouslyenlarged and partially fused to the marginal tubercles, having the appearanceof Paratexanites. The external (5) tubercles are very clavate and generally ashigh as, or higher than, the central keel. Bifurcations occur, but not the later part of the phragmocone and the body chamber, all ornamentbecomes subdued (Fig. 104). 140 ANNALS OF THE SOUTH AFRICAN MUSEUM _^^%#%
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Keywords: ., bookcentury1800, bookdecade1890, booki, booksubjectnaturalhistory
