. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. FOSSIL MOLLUSCA OF HONDEKLIP 167. Fig. 14. Argobuccinum casus. A. Range of paratypes. Scale = 20 mm. B. Holotype. Scale = 10 mm. Spiral ribbons becoming worn on body whorl, and seen to consist of 2 high ridges connected and covered by outer shell layer. Spiral ridges running on to dorsum of siphonal canal. Very faint rounded axial ridges seen in two specimens, 7 ridges between varices, becoming obsolete on body whorl. Remarks Of the cymatiids currently living on the west coast, A. casus most closely
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. FOSSIL MOLLUSCA OF HONDEKLIP 167. Fig. 14. Argobuccinum casus. A. Range of paratypes. Scale = 20 mm. B. Holotype. Scale = 10 mm. Spiral ribbons becoming worn on body whorl, and seen to consist of 2 high ridges connected and covered by outer shell layer. Spiral ridges running on to dorsum of siphonal canal. Very faint rounded axial ridges seen in two specimens, 7 ridges between varices, becoming obsolete on body whorl. Remarks Of the cymatiids currently living on the west coast, A. casus most closely resembles Argobuccinum pustulosum (Lightfoot). This latter is said to occur in two forms or subspecies (see Kilburn & Rippey 1982: 75), with A. pustulosum proditor (Frauenfeld, 1865) being the west-coast form. Argobuccinum casus generally has a narrower shell even than this west-coast form, lacks the rounded tubercles on the spiral bands, has rounded tubercles rather than elongate ridges on the inner surface of the outer lip, has a more clearly defined siphonal canal, and lacks the short marginal digitiform projections of the lower outer lip. Even on the few specimens showing faint axial ribs, where these intersect the spiral bands, no rounded tubercles are formed as in the living species. The present species was also compared with Pleistocene material of A. pustulosum (Lightfoot) from the Saldanha Bay area, and again, all the differences listed above are 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 original South African Museum. Cape Town : The Museum
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
