Shells of Common Occurrence. 143 
Of the Helices proper, we figure fifteen different 
species ; they are mostly too well known to require to 
be more than mentioned. Of these the largest and 
most familiar, Helix aspersa, or common snail (Tig, 
23), is the largest and most destructive in the 

26-27. 
3. Helix aspersa (the Common Snail), Miller. 24-25. H. 
revelata (the Green Snail), Férussac. 26-27. H. nemoralis 
(the Girdled Snail), Linneus. 
garden. Its usual diameter is an inch and a-half. 
It is olive coloured, with dark brown bands. The 
shell is in reality not slimy, though apparently rough 
on the surface. It is alleged that barrels are ex- 
ported as a dainty to America, and that the London 
markets are largely supplied with it as a remedy 
for pulmonary complaints. In the United States 
it has been successfully acclimatized, and is now 
