In the early 1900's shells of a large freshwater mussel, Margaritifera auriculari (Spengler), were discovered in calcreted gravel dredged from the channel of the Thames at several sites between Mortlake and Battersea in west London. These specimens were said to have been associated with Neolithic polished stone axes, supposedly as food remains. M. auricularia is now extinct in Britain, but it has been reported living in several large rivers in southern Europe although apparently not in recent years Three radiocarbon dates of 4140 ± 50,4340 ± 45 and 4860 ± 40 BP have been obtained from Thames specimens, supporting a Neolithic age for these shells. The theory that the shells represent debris from imported human food is discounted and it is considered more likely that M. auricularia was actually living in the Thames in Neolithic times. Its extinction in Britain should be seen as part of a general recession during the Postglacial, as revealed by fossil occurrences to the north and east of its present-day range. -- AATA