. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. REVISION OF LATE VALANGINIAN CEPHALOPODA 327 --tffiliWflffk. Fig. 177. Olcostephanus {Olcostephanus) filosus (Baumberger) (after Bayle 1878), x 1. Olcostephanus elongatus (Tzankov) (Fig. 175) is based upon a strongly compressed, crushed juvenile only 20 mm in diameter. There are about 20 primaries on the outer whorl which terminate in bullae on the umbilical shoulder, from which arise 4-5 prorsiradiate secondaries, some of which occasionally bifurcate. Parabolae are lacking and the outer whorl shows
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. REVISION OF LATE VALANGINIAN CEPHALOPODA 327 --tffiliWflffk. Fig. 177. Olcostephanus {Olcostephanus) filosus (Baumberger) (after Bayle 1878), x 1. Olcostephanus elongatus (Tzankov) (Fig. 175) is based upon a strongly compressed, crushed juvenile only 20 mm in diameter. There are about 20 primaries on the outer whorl which terminate in bullae on the umbilical shoulder, from which arise 4-5 prorsiradiate secondaries, some of which occasionally bifurcate. Parabolae are lacking and the outer whorl shows a rapid increase in height (? due to crushing). This species is close to O. astieriformis but seems to be more densely ribbed and is thus doubtfully separable from O. symonensis (Bose). Olcostephanus filosus (Baumberger) (Fig. 176) is a rather compressed macroconch species with a moderately wide umbilicus and steep umbilical walls. About 26 slightly rursiradiate primary ribs terminate in bullae on the umbilical shoulder and give rise to bundles of 9-10, very fine, prorsiradiate secondaries between which are fine intercalatories. Parabolae apparently lacking. This species is readily distinguishable from O. astieriformis by its much denser, finer ribbing. Although O. filosus has somewhat more primary ribs than O. sayni, individuals such as that figured by Bayle (1878) (Fig. 177 herein) suggest that this character is somewhat variable and population studies are likely to show that O. filosus is a junior subjective synonym of O. sayni. Unfortunately the concept of O. filosus has become somewhat confused by the inclusion of the specimen figured by Matheron (1878) as Ammonites mittreanus [sic] d'Orbigny into Baumberger's (1907) species. Matheron's (1878) example (Fig. 178) is. 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 origi
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
