14 Our British Snails 



find the big Helix pomatia, only found in a few 

 English counties, and very local there. If we 

 were very fortunate, we might find a sinistral, 

 or ** left-handed " specimen. In the case of the 

 pomatia on the right hand there is shown the 

 thick epiphragm which the mantle secretes before 

 the mollusc hibernates. It hardens on exposure 

 to the air like plaster-of-paris ; but is not a true 

 operculum, for that is a constant possession of 

 the shells which have it. Opercula are mainl}^ 

 found in marine or fluviatile shells, and may be 

 either horny (like the winkle) or stony. Amongst 

 our British land shells Cyclostoma elegans and 

 Acicula lineata alone have true opercula, though 

 others form some thin epiphragm for the exclusion 

 of cold air and enemies when they hibernate. 



Most shells grow to the right, and a freak which 

 does the contrary is so rare that of the millions 

 of the common H. virgata that I have seen and 

 handled, only one delighted me with its left- 

 handedness. If it is early summer (nearly all 

 snails hide, burrow, and sleep during the winter), 

 look about on the grass for some half-chalky, 

 half -stony shields, which are the winter front 

 doors of H. pomatia, now discarded ; while 

 sharper eyes might even descry the flinty little 

 darts with which they have been love-making. 

 The illustration on p. 15 shows three of these 

 darts, much magnified. Only the most highly 

 developed Helices possess these courting weapons. 



