| 41. | The siphuncle is large, located subcentrally to resting on the ventral margin.
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| 42. | The suture and siphuncle are characteristic of the family.
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| 43. | The ventral siphuncle is small, with oblong segments.
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| 44. | Septal necks are straight, making the siphuncle orthochoanitic.
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| 45. | The siphuncle is small, subcentral, and orthochoantic.
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| 46. | The siphuncle is located close to the ventral wall.
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| 47. | The siphuncle is slightly ventral of the center . (, 1964 K427)
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| 48. | The suture has broad ventral and lateral lobes, the siphuncle is central.
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| 49. | The siphuncle, which is narrow and tubular, is variable in position.
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| 50. | The distinguishing feature of Tajaroceras lies within its siphuncle.
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