Subprionocyclus neptuni Subzone

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The subzone is characterised by a diverse ammonite assemblage that is distinctive of the Chalk Rock, including common Subprionocyclus spp., Sciponoceras, Allocrioceras spp., Didymoceras saxonicum, Hyphantoceras reussianum, Scaphites spp., Lewesiceras spp., Psedojacobites farmeryi and Tongoboryoceras rhodanicum (Wright, 1979; Gale, 1996). The subzone appears to equate with the lower part of the S. plana Zone, between the Bridgewick Marls and the Lewes Marl / Hitchwood Hardground (Gale, 1996).