. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. CRETACEOUS FAUNAS FROM SOUTH AFRICA 165 weaker, and eventually lateral ornament consists of broad, low ribs that end or weaken considerably before reaching the clavate ventrolateral tubercles. At the same time there is a tendency towards a decrease in the number of bifurcations. On the outer whorls of the specimens available, virtually all ribs are single. De- tail of the ornament varies considerably, from densely costate as in SAS Z1616 (Fig. 27) to sparsely costate in NMB D1146 (Fig. 24). The speci
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. CRETACEOUS FAUNAS FROM SOUTH AFRICA 165 weaker, and eventually lateral ornament consists of broad, low ribs that end or weaken considerably before reaching the clavate ventrolateral tubercles. At the same time there is a tendency towards a decrease in the number of bifurcations. On the outer whorls of the specimens available, virtually all ribs are single. De- tail of the ornament varies considerably, from densely costate as in SAS Z1616 (Fig. 27) to sparsely costate in NMB D1146 (Fig. 24). The species may grow to a very large size. The suture is highly incised (Fig. 28). Discussion In the absence of type specimens, interpretation of this species presents difficulties. It is here interpreted in terms of the specimen from near Altenessen. Fig. 24. Peroniceras (Peroniceras) westphalicum (von Strombeck. 1859). NMB D1146, specimen with typical ornament consisting of low. broad ribs, x 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 South African Museum. Cape Town : The Museum
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
