| Thus, the gerontic aperture of these dextrally coiled shells is situated on the left side in apertural view. |
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| The shells showed severe abrasion of the whorls, whereas their apertural margins were more resistant and were subjected to almost no abrasion. |
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| The edge of the outer lip is crenulated, and usually has a weakly convex profile when viewed from the apertural side of the shell. |
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| Mitral sclerites bilaterally symmetrical, subcircular in apertural view, and subconical in lateral view. |
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| The merging occurs near the apertural margin, indicating the specimen was fossilized shortly after ontogenetic merging. |
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| Thus, the presence or absence of an apertural slit does not necessarily have significance for high-level taxonomy. |
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| In summary, based mainly on its apertural features, the following new species is questionably assigned to genus Ringicula. |
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| In many ammonites the terminal body chamber is relatively large, inflated, and with a constricted aperture or apertural appendages. |
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| Only a few shells measured had teeth or conspicuous apertural thickening, and these features were not measured in this study. |
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| In addition, the apertural region of the conch is depicted as flaring outward, but any such flaring on the specimen itself is subtle at best. |
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| In contrary to those two shell layers produced in the apertural area of the shell, there is another which is made all over the pallium on the inside of the shell. |
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| Rapid growth of the inner and basal parts of the apertural margin during their late shell ontogeny caused twisting of the gerontic whorl both outwards and backwards. |
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| In Trajana, the varix is formed by an outer lip that expands and curls over toward the aperture, bringing the external ribbing over onto the apertural face of the varix. |
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| Ratio of shell length to inter-ocular apertural shell width was 1.94 for both sexes. |
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| Aperture is a simple opening in the center of the apertural face. |
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| Shell length and inter-ocular apertural width were measured for 2067 individuals and digital images of the left, right and dorsal sides taken. |
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| The two species differ in the ornamentation of the apertural margin. |
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| At around 90 mm shell length the color lines at the shell aperture were replaced by a fully white ventral apertural margin, used in previous studies to indicate post juvenile stages. |
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| Various bulla and unusual apertural coverings are present in many taxa severely complicating identification. |
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| Measures included maximum length, maximum width, length of final whorl, length of the spire, apertural length and width, sutural angle, and number of whorls. |
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| Apertural lip expanded and flaring, reflected and incrassate in holotype. |
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| Apertural lip expanded and flaring, not strongly incrassate. |
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