DISPERSAL BY MAN. 263 



from time to time, especially in gardens and green- 

 houses. The finding of two Parmacella-slugs in a 

 garden near Newcastle, of a living shell of Helicina 

 anicena in a nursery at Holloway, and of three exotic 

 land-shells in an orchid-house in Nottingham was 

 referred to in the preceding chapter. No doubt they 

 occur, also, somewhat frequently in shops and ware- 

 houses, generally dead, but sometimes, as in the case of 

 Helix venniculata at Barnsley, in a living state. A 

 grocer at Louth once gave me dead shells of Helix 

 virgata (from amongst raisins) and Helix cespiUnn 

 (from a bag of nuts), and he afterwards found other 

 species. It is probable also that many kinds, brought 

 over from abroad, or received from foreign corre- 

 spondents, like the Helices and ClaKsilice above 

 referred to, or mentioned in the preceding chapter, 

 have been intentionally turned out. Helix terrestris, 

 which may possibly obtain a permanent footing, was 

 very probably thus introduced, and it has been recently 

 transplanted by the Rev. J. W. Horsley to his garden 

 at Woolwich. Some South American snails, as already 

 noticed, turned out in an English garden, are known to 

 have survived at least for three or four years. 



