Bucaniidae

See text Bucaniidae is an extinct family of Paleozoic molluscs of uncertain position possibly being either gastropods or monoplacophorans in the superfamily Bellerophontoidea.

The family lived from the Lower Ordovician to the Devonian and have shells in which the apertural margins tend to flare.

J.B. Knight et al, in 1960[2] included the bucaniids in the Bellerophontidae as the subfamily Bucaniinae, and considered them true gastropods belonging to the prosobranch order, Archaeogastropoda, giving evidence that embryonic torson is not the cause of asymmetric coiling of typical gastropod shells.

Physiologic restriction points to the viscera being turned 180 degrees with the gills and anus to the front and the aperture positioned to best facilitate retreat inward by the head and foot.

[1] The type description reads as follows: Symmetric, involute shells; whorls rather numerous, merely in contact, or embracing slightly, all visible in the umbilicus; aperture often expanded abruptly; dorsal slit-band distinct, the slit itself generally very long and narrow, sometimes represented by a row of openings; surface with transverse lamellae or lines, usually crossed at right angles by short ribs.This article incorporates public domain text from reference.