The BactritidaeErben H.K. 1964; Bactritoidea, in the Treatise on Invertebrate Paleontology Vol K Nautiloidea, K491 –, Teichert, C and Moore R.C. Eds, GSA and Univ Kansas Press. 1964) 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.
