96 On the Land and Fresh- water Molliisca 



the district, aud no species of Vertitjo has been recorded. 

 Some species exist in all probability, but none of my friends 

 who have searched for shells have found them, nor have I 

 been more fortunate, although in other parts of the country 

 I have experienced no difficulty in detecting Vertu/os when 

 inhabiting the locality. 



Balia per^-ersa, Linn. — I found this snail once, commonly, 

 under the bark of a dead poplar, near the Decoy, West 

 Mersea, and this is the only situation in which I know of its 

 occurrence. 



Clausilia rugosa, Drap. — Locally abundant, and occur- 

 ring in many parts of my district sparingly. I think they are 

 most frequent on the Boulder Clay formation. I have not 

 recognized any of the named varieties. 



CocHLicopA TRiDENS, Pult. — I liave uo doubt this occurs, 

 although I have never found it. It occurs sparingly at 

 Wiston, on the Suffolk side of the Stour. 



C. LUBRicA, Miill. — Frequent in all parts of the district, but 

 I have not been able to distinguish any of the named 

 varieties. 



AcHATiNA AcicuLA, Mil 11. — I havc ncver met with the living 

 snail, but dead shells are found in all parts of the district. 

 It is said to occur only on calcareous soils, but I find the 

 shells most frequently in the sandy and gravelly soil around 

 the town. In the rubbish and growing sods of grass on the 

 Eoman wall it is frequently noticed, and some years since a 

 Roman cloaca near the castle was opened, and m the soil at 

 the bottom of the di-ain this shell occurred in thousands. 

 There is one way to find it that I have never seen mentioned. 

 It is to search the tops of the hills of the small ants in the 

 open fields, on any soil, and amongst the earth the insects 

 bring up the shells may generally be found, frequently 

 washed clean by the rain which has percolated the soil. 



CARYCHIIDiE. 



Carychium minimum, Mlill. — Common everywhere in damp 

 spots in meadows, hedges and woods. Easily found by 

 employing the winnowing process. 



