Pristiograptus ludensis occurs in uppermost Wenlock shales and the Wenlock limestone of the Ludlow area (England). The P. ludensis (formerly P. vulgaris) zone is therefore considered to belong largely if not entirely to the Wenlockian. It is suggested that the base of the P. nilssoni zone be considered the Wenlock-Ludlow boundary, rather than the base of the P. ludensis zone.

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