HELIX ASPERSA. 245 
Though usually retiring to their habitual resort at the roots of trees, 
shrubs, or herbage, the sheltered base of walls or rocky hibernacula for 
their daily siesta, yet specimens are found not unfrequently affixed to the 
stems and leaves of shrubs or trees fully exposed to the sun’s rays; but 
this is more frequently the case with immature shells than adults, which 
have more probably a regular place of mid-day resort. 
In Australia, Mr. C. I. Musson has recorded this species as sheltering 
during estivation in large numbers inside the cut hollow stems of the 
bamboo, reminiscent of those ancient shells found fossilized inside the 
Calamite stems of the Carboniferous strata of North America. 
In addition to these casual places of shelter and rest, there are found in 
certain districts where the species abounds, innumerable vertical borings or 
perforations in the carboniferous limestone rocks, especially in those cliffs 
with a northern or north-eastern aspect, which have a very striking family 
likeness, and present similar features.  //eliv aspersa is credited with 
excavating these cavities in the rocks, which, im some districts are almost 
honeycombed by them, and though probably made and chiefly tenanted by 
H. aspersa, are occasionally occupied by other species not only for hiber- 
nation and estivation, but as places of regular resort for rest and shelter. 
Fic. 320.—Helicidian Cavities or Hibernacula in the limestone of Great Orme's Head, Llandudno, 
as seen from beneath (slightly reduced, from photograph by Mr. R. Welch). 
The ability of this species to excavate these rock dwellings in the course 
of ages can scarcely be questioned, as in addition to their demonstrated 
power to abrade limestone and chalk with their odontophores, M. Bouchard- 
Chantereaux, who studied these perforations at Bas Boulonnais, Boulogne, 
during many years, noting and measuring their gradual increase in depth, 
was convinced that H. aspersa was the author, especially as upon lifting 
the snails from the perforations, he found their mucoid secretion gave a 
distinctly acid reaction, perceptibly reddening litmus paper, and thus would 
tend to dissolve or disentegrate the rock. 
