Promicroceras planicosta (Sowerby)
Beautifully preserved calcitic Ammonite on grey limestone. The 'classic' Lyme Regis Ammonite.
Jurassic, Upper Sinemurian, Obtusum Zone. Black Ven, Charmouth / Lyme Regis, Dorset.
Ammonite : 2.5 cm diam.