. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. - ; . --, ?,. Fig. 72. Olcostephanus (Olcostephanus) rogersi (Kitchin) ($). The holotype of Rogersites modderensis (Kitchin), BM-C32201. X 0,75. ribs become almost radial. From the umbilical bullae, bundles of three, very rarely only two, radial secondaries pass straight across the venter, although on the adoral portion of the body chamber, with the egression of the umbilical seam, they become distinctly prorsiradiate. There is a deep oblique parabola about 180° from the peristome, the adapical
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. - ; . --, ?,. Fig. 72. Olcostephanus (Olcostephanus) rogersi (Kitchin) ($). The holotype of Rogersites modderensis (Kitchin), BM-C32201. X 0,75. ribs become almost radial. From the umbilical bullae, bundles of three, very rarely only two, radial secondaries pass straight across the venter, although on the adoral portion of the body chamber, with the egression of the umbilical seam, they become distinctly prorsiradiate. There is a deep oblique parabola about 180° from the peristome, the adapical rib of which is prominently flared. The peristome is virtually identical to this parabola except that the posterior margin is even more prominently flared, while the adoral rib bears well-preserved lateral lappets which have a subhorizontal twist to them. Macroconch (?): in the slightly crushed holotype of O. modderensis (Kitchin) (Fig. 72), which represents merely the inner whorls of the macroconch of this species, well-developed rursiradiate primary ribs terminate in about 16 sharp umbilical bullae on the outer whorl. These give rise to bundles of commonly 3, occasionally 4, very coarse, radial secondaries, generally with an intercalated rib between bundles. The secondary ribbing may become slightly prorsiradiate as a parabola is approached. There is a very prominent, deep, oblique parabola on the outer whorl. The following is a description of the holotype of O. kitchini (Spath) based on a plastotype supplied by M. K. Howarth: the shell is gigantic, extremely inflated, with a very depressed whorl section. The umbilical seam of the outer whorl has already begun to egress, showing it to represent part of the body chamber. The umbilicus is narrow and very deep. The umbilical walls of the penultimate whorl are very steep, convex, and ornamented with 17 prominent rursiradiate primaries which begin at, or close to, the umbilical seam and terminate in prominent bullae on the umbili
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
