. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 310 ANNALS OF THE SOUTH AFRICAN MUSEUM. Fig. 161. Olcostephanus {Olcostephanus) singularis (Baumberger). The lectotype, designated herein, from the Swiss Jura (after Baumberger 1908). x 1. of the umbilical seam displayed by O. uitenhagensis in maturity, as well as commonly retaining bullate umbilical tubercles to the peristome. Olcostephanus singularis (Baumberger) (Fig. 161) is the closest species to O. uitenhagensis. It has a moderately inflated shell with a strongly depressed whorl section and sho
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 310 ANNALS OF THE SOUTH AFRICAN MUSEUM. Fig. 161. Olcostephanus {Olcostephanus) singularis (Baumberger). The lectotype, designated herein, from the Swiss Jura (after Baumberger 1908). x 1. of the umbilical seam displayed by O. uitenhagensis in maturity, as well as commonly retaining bullate umbilical tubercles to the peristome. Olcostephanus singularis (Baumberger) (Fig. 161) is the closest species to O. uitenhagensis. It has a moderately inflated shell with a strongly depressed whorl section and shows marked egression of the umbilical seam on the outer (?fmal) whorl. About 12, rounded, swollen, umbilical tubercles on the outer whorl give rise to bundles of 5-6 slightly prorsiradiate secondaries, between which are 2-3 intercalated ribs. Parabolae are lacking. This species differs from O. uitenhagensis in that the umbilical tubercles are swollen and rounded even on the inner whorls as witnessed by O. klaatschi (Wegner) which is merely based upon a juvenile of Baumberger's (1908) species. Olcostephanus rabei (Besairie) (Fig. 69A-B), as noted by Besairie (1936), is indeed very close to the inner whorls of O. uitenhagensis. However, without knowledge of the final whorls, the true affinities of O. rabei are obscure as it also closely resembles O. sakalavensis. Occurrence This species has been known with certainty only from South Africa, although Reyment & Tait (1972) have recently reported its occurrence in 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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