. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . ext-fig. 3) differs from the present species in having coarse,simple flank costae, without bifurcation or intercalation. Prionocyclus cobbaniMatsumoto (1965: 21, pi. 4 (figs 1-4), text-fig. 7) and P. reesidei Sidwell (1932: 318,pi. 49 (figs 10-12); Matsumoto 1965: 21, pi. 17 (fig. 1)) also are more coarsely ribbed,with only 29-38 ribs per whorl, as is P. hyatti (Stanton) (1894: 176, pi. 42 (figs 5-8);Matsumoto 1965: 19, pi. 17 (fig. 3)); the latter species also has flank costae differentiatedinto those that are stro
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . ext-fig. 3) differs from the present species in having coarse,simple flank costae, without bifurcation or intercalation. Prionocyclus cobbaniMatsumoto (1965: 21, pi. 4 (figs 1-4), text-fig. 7) and P. reesidei Sidwell (1932: 318,pi. 49 (figs 10-12); Matsumoto 1965: 21, pi. 17 (fig. 1)) also are more coarsely ribbed,with only 29-38 ribs per whorl, as is P. hyatti (Stanton) (1894: 176, pi. 42 (figs 5-8);Matsumoto 1965: 19, pi. 17 (fig. 3)); the latter species also has flank costae differentiatedinto those that are strong, umbilically bullate and horned, and those that are weak,non-bullate, and hornless (Kennedy & Cobban 1988). Stratigraphical occurrence Prionocyclus novimexicanus (Marcou) is known from the upper Middle and low UpperTuronian of North America (Wyoming, S. Dakota, New Mexico), Japan and probably Angola. Genus Prionocycloceras Spath, 1926 Type species Ammonites guayabanus Steinmann, 1881; by original designation of Spath (1926: 80). 134 ANNALS OF THE SOUTH AFRICAN MUSEUM.
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Keywords: ., bookcentury1800, bookdecade1890, booki, booksubjectnaturalhistory
