The introduction of Cochlicella acuta and Cochlicella barbara into Britain and the extinction of Xerocrassa geyeri in Cornwall

Abstract

The introduction into Britain of two helicid species, Cochlicella acuta and C. barbara, is discussed in the knowledge that old carbon may have influenced the chronology; modern specimens of C. acuta from Cornish sand dunes gave radiocarbon dates which are 600−800 years old. The introduction of C. acuta is confirmed to the early Bronze Age and it may have been present in the late Neolithic. C. barbara arrived in Cornwall prior to its first observation in the 1960s but, in view of the old carbon problem, a precise date cannot be determined. Xerocrassa geyeri became extinct in most of southern Britain in the early Holocene, but survived at Gwithian in Cornwall for several more millennia, with radiocarbon dating suggesting that it could have been present there until the later part of the early Bronze Age.