Strigoceras gracile.
Strigoceras were a group of unusual Ammonites. They are characterised by a series of Strigations (these are raised longitudinal ridges) running right round the surface of the shell. These have been interpreted as a feature which may improve movement though the water column.and thus increase swimming speed. Fine complete specimen showing strigations and beautiful sutures. Really good Strigoceras are hard to obtain.
Jurassic, Bajocian, Truelli Bed.
Burton Bradstock, Dorset.
Ammonite : 11.5 cm diam.