Hexameroceras

Hexameroceras is a genus of nautiloid cephalopods belonging to the order Oncocerida that lived during the middle and late Silurian. Its fossils have been found in North America in Indiana, New York, Ohio, and Wisconsin, and in Europe in the Czech Republic (Czech Republik according to TUREK, 2009).

Hexameroceras is similar to Tetrameroceras but has 3 pairs of dorsolateral sinuses (lateral embayments in the aperture) and narrow mid-dorsal projection or salient. The shell, as for the family, is breviconic, i.e. short, curved toward the apex, straight toward the aperture. The siphuncle is ventral, nummuloidal and contains inwardly radial actinosiphonate deposits.

• Walter C. Sweet, 1964. Nautiloidea - Oncicerida, Treatise on Invertebrate Paleontoloty, Part K. Geological Society of America.
• Turek, V. (2009): Colour Patterns in Early Devonian Cephalopods from the Barrandian Area: Taphonomy and taxonomy.- Acta Palaeontologica Polonica 54 (3): 491 - 502; Warschau. (PDF) Colour Patterns in Early Devonian Cephalopods from the Barrandian Area: Taphonomy and taxonomy

• Turek, V.. & Manda, Š. (2011): Colour pattern polymorphism in Silurian nautiloid Phragmoceras BRODERIP,1839. Bulletin of Geosciences 86(1), 91–105 (9 figures, 1 table). Czech Geological Survey, Prague. ISSN 1214-1119 1240_turek_manda.vp.
• Dzik, J. (1984): Phylogeny of the Nautiloidea.- Palaeontologica Polonia 45 (WITH 72 TEXT·FIGURES AND 47 PLATES). Warschau/Krakau 1984_45.pdf
• Hexameroceras in Fossilworks Gateway.