134 The Mollusca of Cambridgeshire 



Grantchester, in which no marine, species occur hut which an- 

 very rich in freshwater and terrestrial forms. Musi f tlms,- 

 at present known arc still inhabitants of Cambridgeshire, 

 while some have apparently died ont, though still living in 

 the bordering or in more distant counties. There are also 

 about half-a-dozen which are no longer British. On the other 

 hand there are two or three species not found in the gravels 

 which are living inhabitants of the county. 



Species from the local gravels which do not now live in 

 Cambridgeshire or at all events in the neighbourhood of Cam 

 bridge though still to be found within the British Isles are: 



Limax arbwum, Bouch. -Chant., which is widely distrihuird 

 on the Continent and in the British Isles, does not appear to 

 have been found alive in Cambridgeshire, though it occurs in 

 the bordering county of Northampton. It has also been found 

 in a Holocene deposit containing unglazed Romano-British 

 pottery at Harlton 1 . 



Acanthinuld lamellata (Jeff.), which now lives in England 

 as far south as the neighbourhood of Heading and also occurs 

 in Scotland, northern Ireland, Sweden and northern Germany. 

 This species has trended northward, at the same time becoming 

 rare or dying out in the south 2 . 



Helicodonta obvoluta (Mull.), the "cheese snail," wliich is 

 fairly common throughout Central Europe but is apparently 

 dying out in England, wherein it is confined to beech woods 

 on the chalk hills of Hants, Sussex and Surrey. The single 

 example which has been obtained from the Grantchester 

 Gravels is the only evidence of the range of this species 

 north of the above counties. 



Ena montana (Drap.) occurs locally but fairly numerously 

 in the south and west of England, but in East Anglia seems 

 to have been recorded only from West Si i Hoik. On the 

 Continent it ranges from Silesia to the Pyrenees. 



1 K. A. Bullen, Proc. Malacol. Soc. London, \., I'.M).",, )>. :Jls. 

 - I itle 15. I',. W<.o<lw:ircl, I'roc. M.ilacol. Sor. Lund., \., I'.M):;, p. li, 

 for details of the present ran^e of this speeii-s in 



