Additions to the molluscan fauna of the early Middle Pleistocene deposits at Sugworth, near Oxford, including the first British Quaternary record of Perforatella bidentata (Gmelin)

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Shells recovered from large bulk samples of tise interglacial sediments from Sugworth, originally processed for vertebrate remains by Dr. A. J. Stuart, have provided several additional records. These include Discus ruderatus, Cochlicopa lubricella, Gyraulus acronicus, Clausilia bidentata and have confirmed records of Clausilia pumila. The most noteworthy record however, is Perforatella bidentata, a woodland snail with an east European modern range, hitherto unknown from the British Quaternary. Several elements of the mollusean fauna suggest a certain degree of climatic continentality. An early Middle Pleistocene interglacial age, pre-dating the Anglian, is reaffirmed on the basis of molluscan and vertebrate evidence. Independent support is also provided by amino acid ratios derived from the shells of Valvata. A recent suggestion that the deposits should be assigned to the late Hoxnian, on the basis of altimetric arguments, is rejected.