Annals of the South African MuseumAnnale van die Suid-Afrikaanse Museum . 7571, 7572 (2 specimens), 7573-74, 7575 (2 specimens), 7595, 12776, D574,D1944 and two unnumbered specimens, there are also several unnumberedspecimens in the Port Elizabeth Museum. Description Shell medium sized (maximum length about 65 mm), trigonally ovate,elongate (H/L = 0,52-0,61), with the moderately elevated umbones situatedabout one-third of the shell length from the anterior. The posterodorsal marginis shallowly concave, the anterior margin strongly convex passing imperceptiblyinto the broadly convex ventral mar
Annals of the South African MuseumAnnale van die Suid-Afrikaanse Museum . 7571, 7572 (2 specimens), 7573-74, 7575 (2 specimens), 7595, 12776, D574,D1944 and two unnumbered specimens, there are also several unnumberedspecimens in the Port Elizabeth Museum. Description Shell medium sized (maximum length about 65 mm), trigonally ovate,elongate (H/L = 0,52-0,61), with the moderately elevated umbones situatedabout one-third of the shell length from the anterior. The posterodorsal marginis shallowly concave, the anterior margin strongly convex passing imperceptiblyinto the broadly convex ventral margin, and the respiratory margin narrowlyrounded. The valves are moderately inflated anteriorly (H/W = 0,33-0,36). The sunken escutcheon is narrow, lanceolate, smooth, and extends about50 per cent of the posterodorsal shell length. It rises slightly at the area is narrow, smooth beyond the nepionic stages, and with a longitudinalgroove that weakens and may become obsolete posteriorly. Inner and marginal LOWER CRETACEOUS TRIGONIOIDA FROM THE ALGOA BASIN 45. Fig. 24. Iotrigonia vau (Sharpe), x 1. A. Lateral view of the specimen in the South AfricanMuseum figured by Kitchin (1908). B-C. Lateral and dorsal views of a right valve in the PortElizabeth Museum. D. Right valve of a posteriorly elongate individual in the Port ElizabethMuseum. E-F. Lateral and dorsal views of a left valve in which the posterior branches of theflank costae are unusually swollen. carinae are lacking. The area is ornamented by transverse costellae for about7 mm from the beak, after which the ribs are restricted to the angulation separ-ating the area and escutcheon. The flank ornament of the nepionic stages, up to a distance of 10 mm fromthe umbones, comprises fine concentric ribs, about as wide as the pass obliquely across the area with a slight inflexion at the position of themarginal carina, and continue weakly on to the outer edge of the escutcheon. 46 ANNALS OF THE SOUTH A
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Keywords: ., bookauthorsouthafr, bookcentury1800, bookdecade1890, bookyear1898
