a. 
244 HELIX ASPERSA. 
HrBeRNATION AND AistivatTion.!—Helix aspersa is a socially gregarious 
hibernant, and very sensitive to cold, sometimes beginning to congregate 
together as early as September, when clusters may occasionally be found 
at the roots of shrubs in hedgerows and elsewhere. Later, with the 
gradually increasing cold, the mouth of the shell is permanently closed 
with the usual epiphragm, and the animals take up their quarters for the 
winter, usually clustering together within holes in rocks or walls, or buried 
even to the depth of several inches in the soil in hedgerows or at the 
foot of walls or herbage. If the periods of frost be intense or long con- 
tinued, the animals shrink further and further within their shells, 
constructing additional epiphragms, until sometimes there may be as 
many as six or even eight, one behind the other, becoming gradually 
thinner and more delicate as they are more internally placed. 
Fic. 319.—Helicidian cavities at Miller's Dale, Derbyshire, more fully exposed by the flaking 
away by frost of the face of the cliff (photographed by Mr. R. Welch). 
When thus prepared against the winter’s cold, they can withstand a 
considerable degree of frost without i injury, as, ace cording to Mr. E. J. Lowe, 
a specimen confined beneath a bell glass, upon a slate base, survived a 
temperature of 14° Fahr. or 18° of frost, a cold which destroyed specimens 
of Arion ater, Limax Navus, Limax maximus, Agriolimax agrestis, and 
Milax sowerbii confined in the same receptacle. 
Immature specimens withstand the cold better than adults, retiring later 
and reappearing earlier. ‘They also revive during the milder days of 
winter, and move about in mild evenings, perhaps’ retiring only during 
periods of actual frost, their more vigorous circulation probably accounting 
for their greater activity and hardihood. 
1 Monog. i., p. 308. 
