A LOWER LLANVIRN GRAPTOLITE FAUNA FROM THE SKIDDAW SLATES, WESTMORLAND

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Abstract
Summary: The Wet Sleddale extension of Manchester Corporation’s Haweswater scheme in Westmorland included the excavation of an aqueduct tunnel to the west of Shap village and entirely within the Skiddaw Slates of the Bampton Inlier. Excavated materials have provided abundant, well-preserved graptolites of late Didymograptus bifidus Zone (Lower Llanvirn) age and their description complements the revision by Jackson (1962) of the graptolite faunas, earlier than the D. bifidus Zone, of the Skiddaw Slates. Twenty-seven species and subspecies belonging to at least nine, and possibly eleven, genera have been recovered. Two new species are described: Diplograptus hollingworthi sp. nov. and Climacograptus tailbertensis sp. nov. Important features of the fauna include the dominance of biserial graptolites and the paucity of specimens referable to the several pendent species of Didymograptus. The extreme rarity of Didymograptus bifidus (J. Hall) is adduced as further evidence in support of the claim that the D. bifidus Zone of North America does not correlate with the British D. bifidus Zone.