| 11. | Where known, the siphuncle tends to be central to subcentral.
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| 12. | The siphuncle swelling at the apex is subtriangular in longitudinal profile.
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| 13. | The siphuncle is small, subcentral, and with recumbent necks.
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| 14. | It differs in having a subcentral siphuncle with somewhat inflated segments.
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| 15. | The siphuncle is subcentral, ventral of the dorsal septal flexture.
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| 16. | The siphuncle is subcentral with segments slightly expanded into the chambers.
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| 17. | The siphuncle is ventral, tubular and free of organic deposits.
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| 18. | The siphuncle is ventral, close to the longitudinally concave side.
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| 19. | Position and structure of the siphuncle were unknown as of 1964.
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| 20. | The siphuncle is ventral, marginal, with continuous actinosiphonate lamellae.
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