Cenoceras semistiatulum (D'Orbigny).
Matrix free undistorted nautilus. Shows septal chambers to perfection. Siphuncle opening showing Nautiloids of this quality from Freshwater are exceptionally rare finds. Found back in the mid 1980's.
Jurassic, Bajocian, Humphriesianum Zone.
Freshwater Caravan Park, Burton Bradstock, Dorset.
Nautilus : 8.5 cm diam.