. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. Fig. 133. Olcostephanus (Olcostephanus) baini baini (Sharpe) (?). The holotype of Roger sites douvillei Besairie (fide Collignon 1962) and also Roger sites baini var. ambikyi Besairie, from the Upper Valanginian of Ambiky, Madagascar (after Collignon 1962). x 1. Discussion As has been pointed out by many previous workers, O. baini (<$) forma typica bears a close resemblance to O. schenki (Oppel) (Fig. 132). It becomes apparent from the present study that the differences are merely those due to a c
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. Fig. 133. Olcostephanus (Olcostephanus) baini baini (Sharpe) (?). The holotype of Roger sites douvillei Besairie (fide Collignon 1962) and also Roger sites baini var. ambikyi Besairie, from the Upper Valanginian of Ambiky, Madagascar (after Collignon 1962). x 1. Discussion As has been pointed out by many previous workers, O. baini (<$) forma typica bears a close resemblance to O. schenki (Oppel) (Fig. 132). It becomes apparent from the present study that the differences are merely those due to a comparison of the inner whorls of a macroconch with a microconch form. Consequently, O. schenki (Oppel) is regarded as a junior subjective synonym of O. baini baini. Riccardi et al. (1971) considered O. schenki to represent the inner whorls of the O. atherstoni macroconch. However, as warned by Makowski (1962a: 21), they failed to recognize the homoeomorphy between macroconch forms. Hence the O. atherstoni fauna recorded by Riccardi et al. (1971) from west-central Argentina includes both O. atherstoni and O. b. baini, as evidenced by the presence of young macroconchs both with and without parabolae. This same phenomenon recurs in the Uitenhage fauna, the homoeomorphy being recognized by the differing rates of inflation of the two forms (Fig. 118). Olcostephanus douvillei (Besairie) (Fig. 133) was erected for strongly inflated forms with commonly three prorsiradiate secondaries per bulla, and parabolae on the inner whorls. This species is undoubtedly conspecific with the O. b. baini macroconch, representing merely an immature growth stage. Olcostephanus baini var. ambikyi Besairie has the same holotype as Q. douvillei and is thus a junior objective synonym. In 1930, Besairie figured an example of O. schenki (Oppel) which he con- sidered '. . tout a fait semblable aux figures d'Uhlig'. The large size and numerous secondaries, together with the presence of parabolae, suggest this.
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