What is "bucaniidae"

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. Most genera have a slit and selenizone, others some modification of this feature.