''Bistrialites'' is an involute, globose Clydonautilacean belonging to the

Liroceratidae Liroceratidae is an extinct family of nautilids, shelled marine molluscs, belonging to the Clydonautiloidea, consisting of generally smooth, involute, nautiliconic forms with a small umbilicus. The whorl section is usually depressed and broadl ...

with a reniform (kidney-shaped) whorl section, large funnel-shaped

umbilicus Umbilicus may refer to: *The navel or belly button *Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy *Umbilicus (plant), ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants *Umbilicus ...

, smooth surface except for spiral ornament in the region of the umbilical shoulder. ''Bistrialites'' comes from the

Lower Carboniferous Lower may refer to: * ''Lower'' (album), 2025 album by Benjamin Booker *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is sit ...

(Mississippian) of Europe.

''References''

*Bernhard Kummel, 1964. Nautiloidea – Nautilida;

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

, Part K. Geological Society of America and University of Kansas press, R.C. Moore (ed.) -- Liroceratidae K444 -K447. Nautiloids {{nautiloidea-stub