. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. Fig. 139. Olcostephanus {Olcostephanus) dacquei (Krenkel). The holotype, by monotopy, from the Mikadi region of Tanzania (after Krenkel 1910). x 1. to the inner whorls of the O. baini macroconch. Topotype material is necessary to determine the specific and subgeneric status of the Spanish species. Olcostephanus dacquei (Krenkel) (Fig. 139) is based upon a juvenile with a rather narrow umbilicus and a depressed, coronate whorl section. Prominent primary ribs terminate in 7 well-developed, somewhat rou
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. Fig. 139. Olcostephanus {Olcostephanus) dacquei (Krenkel). The holotype, by monotopy, from the Mikadi region of Tanzania (after Krenkel 1910). x 1. to the inner whorls of the O. baini macroconch. Topotype material is necessary to determine the specific and subgeneric status of the Spanish species. Olcostephanus dacquei (Krenkel) (Fig. 139) is based upon a juvenile with a rather narrow umbilicus and a depressed, coronate whorl section. Prominent primary ribs terminate in 7 well-developed, somewhat rounded umbilical tubercles from which arise 4-5 prorsiradiate secondaries, frequently with an intercalated rib between bundles. There are about 37 ribs per half whorl, as well as two prominent parabolae. This species differs from O. baini in possessing fewer umbilical tubercles from which arise finer, more numerous secondary ribs. The holotype of O. sublaevis Spath (Fig. 140) is entirely septate and seems to be based upon the inner whorls of a macroconch. Based upon Fatmi's (1977) interpretation of this species, there are about 20 rursiradiate primaries (cer- tainly more in Spath's holotype) which terminate in bullae on the umbilical shoulder and give rise to 4-6 slightly flexuous, prorsiradiate ribs. There is little to distinguish this species from the O. baini macroconch, of which it seems. Fig. 140. Olcostephanus {Olcostephanus) sublaevis Spath (?). The holotype from the Spiti Shales of Pakistan (after Spath 1939). 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
