. Annals of the South African Museum. Annale van die Suid-Afrikaanse Museum. 270 ANNALS OF THE SOUTH AFRICAN MUSEUM. Fig. 61. Mortoniceras (Durnovarites) perinflatum (Spath). The holotype, Pictet collection, Natural History Museum, Geneva. From the Upper Albian of Vraconne, Switzerland, xl. Description The shell is moderately inflated and rather evolute (umbilicus 32-36% of the diameter), with a wide, shallow umbilicus and steep umbilical walls. The whorl section is almost quadrate (w/h = 0,93-1,05), with subparallel flanks. The umbilical shoulder is evenly rounded intercostally. Ribs begin at
. Annals of the South African Museum. Annale van die Suid-Afrikaanse Museum. 270 ANNALS OF THE SOUTH AFRICAN MUSEUM. Fig. 61. Mortoniceras (Durnovarites) perinflatum (Spath). The holotype, Pictet collection, Natural History Museum, Geneva. From the Upper Albian of Vraconne, Switzerland, xl. Description The shell is moderately inflated and rather evolute (umbilicus 32-36% of the diameter), with a wide, shallow umbilicus and steep umbilical walls. The whorl section is almost quadrate (w/h = 0,93-1,05), with subparallel flanks. The umbilical shoulder is evenly rounded intercostally. Ribs begin at the umbilical seam and are rectiradiate to the umbilical shoulder where they termi- nate in weak bullae. The latter give rise to 1-2 prorsiradiate flank ribs, 38-43 per whorl and broader than the interspaces. All ribs are ornamented by a midlateral tubercle and closely spaced upper and lower ventrolateral tubercles. On the venter, the ribs pass forwards, finally becoming effaced in the sulci bordering the siphonal keel. The ribs show spiral ornament which is especially prominent on the ventrolateral 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 [etc. ] The Museu
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Keywords: ., bookauthorsouthafr, bookcentury1800, bookdecade1890, bookyear1898
