| 11. | :Considering the evolute of a curve may help.
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| 12. | The shell of " Gastrohoplites " is variably involute to evolute.
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| 13. | It is neither a product of evolution, nor the cause of any evolute.
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| 14. | It follows that the contrapedal of a curve is the pedal of its evolute.
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| 15. | Vertices of " C " correspond to singular points on its evolute.
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| 16. | The shell is evolute, inner whorls exposed; whorls compressed and slightly overlapping.
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| 17. | Generally small, evolute with round, oval, square or rectangular whorl sections.
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| 18. | The shell is evolute, compressed in section.
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| 19. | The caustic of the normal map is the evolute of " M ".
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| 20. | Curves with the same evolute are parallel.
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