. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. % Fig. 2. Whorl section of Eubaculites latecarinatus (Brunnschweiler). A. SAM-PCO5908. B. SAM-PCO5909. C. SAM-PC05913. All from locality C (TBD 1336) in the Alphard Group, x 1. Description Virtually all ontogenetic stages of this species are present in the collection, though it is not known if they all belong to the same individual. At the earliest preserved stage, at Wh = 12 mm, the whorl section is ovoid, with a narrowly rounded venter (Fig. 2C). At wh = 26 mm, however, the whorl section is more co
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. % Fig. 2. Whorl section of Eubaculites latecarinatus (Brunnschweiler). A. SAM-PCO5908. B. SAM-PCO5909. C. SAM-PC05913. All from locality C (TBD 1336) in the Alphard Group, x 1. Description Virtually all ontogenetic stages of this species are present in the collection, though it is not known if they all belong to the same individual. At the earliest preserved stage, at Wh = 12 mm, the whorl section is ovoid, with a narrowly rounded venter (Fig. 2C). At wh = 26 mm, however, the whorl section is more compressed with a flattened dorsum, very weakly inflated flanks and a broad, undulating ventral keel, separated from the flanks by weak, lateral depressions (Fig. 2B). The only ornament at this size consists of weak undula- tions over the ventral keel, and a poorly defined median ridge traversing the dorsum longitudinally (Figs 3A-C, 5D). Increase in size at this stage is rapid, 18,3 according to Matsumoto & Obata's (1963: 4) index (increase in heights \ distance '/ On later parts of the phragmocone and on the body chamber, the whorl section is distinctly pyriform, with a well-defined, crenate ventral keel, separ- ated from the flanks by a lateral furrow on either side, and a flat dorsum with a distinct median ridge (Fig. 2A, 3D) which is present on internal moulds and on the preserved shell. A specimen from the Maastrichtian of Zululand (Fig. 4) shows the adult features of the species, which still includes a total lack of lateral ornament but a slower growth index (13,4). In this Zululand specimen the dorsal median ridge appears slightly undulating. The suture is very incised, and the septae closely spaced. The saddles and lobes are low and broad (Figs 3A-C, 5D).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
