the apical angle may be small or large, and the protoconch is globular to egg-shaped. The Bactritida comprise two families, the Bactritidae and the Parabactritidae.

Bactritidae

The Bactritidae are characterized by long orthoconic to cyrtoconic shells with a small apical angle (less than 10°) and septal necks that are orthochoanitic. Chamber length is variable. The Bactritidae contain eight recognized genera. Bactrites has the longest range, from the Lower Devonian to the Upper Permian, and even possibly from the Silurian.The

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