KENNARD: HOLOCENE non-marine MOLLUSCA of ENGLAND. 247 



from the Forest Bed (Cromerian) of West Runton, Norfolk, as well 

 as from a number of Pleistocene deposits, being fairly common at 

 Woodston, Northamptonshire, and Clacton, Essex. It is possible 

 that it may yet be found living, but I think that the story of its 

 occurrence at Grange-over-Sands, Lancashire, probably arises from 

 an error in locality. 



Fruticicola (Ponentina) montivaga (Westld.) was found in the 

 deposits at Harlyn Bay, Cornwall, by the Rev. R. Ashington Bullen, 

 the only record for the species in England, and it had apparently 

 been able to maintain itself there for some considerable time. But 

 the possibility that it may be only an extreme form of Fruticicola 

 (Ponentina) subvirescens (Bellamy) must be remembered. 



Unio auricularius (Spengl.) has been dredged in some quantity 

 from the gravels of the Thames at Barn Elms and Mortlake. The 

 gravels from which these shells have been obtained have recently 

 been claimed to be of Pleistocene age. 



G. F. Lawrence, through whose hands passed all the specimens 

 that have been obtained, informed me that polished stone axes 

 also occur in these gravels, but no metal objects, thus proving con- 

 clusively that the associated shells are early Holocene and not 

 Pleistocene, a conclusion strongly supported by the other mollusca 

 found with the Unios {Proc. Malac. Soc. Lond., Vol. X, 1913, p. 332). 

 There are eight species of which it can be definitely said that 

 their area of distribution at the present day is much greater than 

 was formerly the case. They are : — 



Helicella draparnaldi (Beck). 



Jacosta [Gernuella) virgata (Da Cost.). 

 J, (Candidula) caperata (Mont.). 

 „ „ gigaxii (Pfr.). 



Theba cantiana (Mont.). 



Fruticicola {Capillifera) striolata (C. Pfr.). 



Helix aspersa Miill. 



Paludestrina jenkinsi (Smith). 

 Known only from the Holocene of Newquay, Cornwall, and Anstice 

 Cove, near Torquay, Devonshire, Helicella draparnaldi (Beck) has 

 now a very wide range, but an examination of the records reveals 

 the fact that many of these are based on occurrences in gardens 

 or even greenhouses, scarcely natural habitats. It is only in the 

 west of England that it occurs away from human habitations, 

 and there alone can it be considered a true native. As already 

 suggested, horticulture has probably been the chief agent in the 

 modern distribution of this form, and it is not improbable that 

 examples of this species were introduced into many parts of England 

 by this means during mediaeval times from the Continent. It is 

 often associated with monastic ruins. This dual origin may account 

 for the slight differences that have been noted in both the animal 

 and the test between the eastern and western forms of this species. 



