AN EARLY NEOLITHIC KITCHEN-MIDDEN. 75 



was commenced in the hope of obtaining some clue to the geological 

 and climatic changes of the county and with a view to collect a 

 good series of fossil plants. In neither of these respects was the 

 result satisfactory ; hut on the other hand we have obtained an in- 

 sight into a prehistoric period of which little was known. Several 

 other questions have been raised, and one of them I should like 

 to mention, as it concerns both archaeologists and naturalists, and 

 we need their help : 



Land snails are not generally thought to be of much account for 

 fixing the age of deposits ; but this is probably a mistake ; they are 

 likely to prove extremely valuable historic medals for the periods 

 before coins were used or history written. Several of our 

 commonest snails seem to have been introduced by human agency, 

 in all probability by accident. They seemingly did not come in all 

 together, but one by one, and if archaeologists will carefully collect 

 the land-shells, which are so abundant in nearly every grave on the 

 Downs, we ought soon to arrive at the date of their introduction, 

 and so be able to use them for fixing the dates of other antiquities 

 of doubtful age. The common Helix aspersa of our gardens, for 

 instance, I have never seen in any deposit satisfactorily shown to 

 be older than the Roman invasion. If this holds good it will be 

 a valuable guide. 



