Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . third of the flanks. The suture line is very incised with trifid L, U and I lobes and bifid saddles. Dimensions Wb. 47,2 (at distal end) Wh. 52,9. Discussion This specimen corresponds approximately to Caseys Lithancylus grandis(Sowerby) specimen figured in his plate 20, fig. lb, where ornament on the shaftchanges from normal to trituberculate ribbing. L. grandis, however, has analmost circular whorl section on the shaft and is not conspecific. L. fustis has adepressed whorl section; L. neleus (Anderson), L. mirabilis
Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . third of the flanks. The suture line is very incised with trifid L, U and I lobes and bifid saddles. Dimensions Wb. 47,2 (at distal end) Wh. 52,9. Discussion This specimen corresponds approximately to Caseys Lithancylus grandis(Sowerby) specimen figured in his plate 20, fig. lb, where ornament on the shaftchanges from normal to trituberculate ribbing. L. grandis, however, has analmost circular whorl section on the shaft and is not conspecific. L. fustis has adepressed whorl section; L. neleus (Anderson), L. mirabilis (Anderson) andL. australe Day have ovoid whorl sections. L. cyclopius (Anderson) has asubtrigonal section as the present specimen, but finer ribbing, as has L. tirolensisCasey. CRETACEOUS FAUNAS FROM SOUTH AFRICA 255 Thomsons (1974) Lithancylus sp. is poorly preserved, but appears to havefiner ribbing at the proximal end. Associated shafts of Ancyloceras {Adouliceras) spp. are all more massiveand have finer ribbing. Occurrence Lower Aptian of southern Mozambique. •JZt,. Fig. 25. Lithancylus sp. SAM-PCM5436 from Lubemba, Mozambique, Lower Aptian. x 1,2. 256 ANNALS OF THE SOUTH AFRICAN MUSEUM Genus Tropaeum J. de C. Sowerby, 1837Type species Tropaeum bowerbanki J. de C. Sowerby, 1837 from the Lower Aptian ofEngland, by monotypy. Diagnosis Generally large; coiling predominantly crioceratitid, but in early speciesthe body chamber may be distinctly uncoiled, giving rise to ancyloceratidor to aspinoceratid forms. Ornament on phragmocone consists of plain ribbingwith occasional umbilical or ventral tubercles in early or late stages. On the bodychamber a rapid change in ornament may take place, with the development ofheavy, distantly spaced ribs. Aperture may be contracted. Dorsum ornamentedby forward directed striae only. Discussion For details on the somewhat unusual manner in which the genus wasintroduced, and the accompanying nomenclatorial implications, see Casey(1960: 24), who
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Keywords: ., bookcentury1800, bookdecade1890, booki, booksubjectnaturalhistory
