54 
STRANGE DWELLINGS. 
In the winter time, each of these holes is occupied by a 
specimen of the Helix saxicava, a small snail, closely resem- 
bling the common banded snail of our hedges ( Helix nemoralis ), 
and it is thought that the holes are excavated by the snail 
which inhabits them. Mr. Hancock, who re-opened in the 
columns of the Field newspaper a controversy respecting these 
snails, which was initiated in 1839, is of opinion that the snails 
really form the hole, and that they burrow at the average rate 
of half an inch per annum. The late Dean Buckland was of 
the same opinion. Other naturalists, however, think that the ■ 
holes were originally excavated by pholades and other marine !j 
molluscs when the rocks in question formed part of the ocean j 
bed, and that the snails merely inhabit the ready-formed holes. J 
Mr. Pinkerton upholds this opinion, and states that at least 1 
three other species of helix possess similar habits, the garden j 
and the banded snail being among the number. 
I have compared the burrows of the mollusc, which we will j 
call the Boring Snail, with those of the pholas and lithodomus, 
both of which will be presently described, and find that there is 
no resemblance in their forms, the shape and direction of the 
holes being evidently caused by an animal of no great length 
in proportion to its width. In my own specimen, every hole 
is contracted at irregular intervals, forming a succession of 
rounded hollows. If we return to our lump of putty, we may | 
form the holes made by the thumb into a very good imitation 
of those in which the Boring Snail lives. After the thumb has 
been pushed into the putty and well twisted round, put in the 
fore-finger as far as the first joint and turn it round so as to 
make a rounded hollow. Push the linger into the hole as far 
as the second joint, and repeat the process. Now introduce j 
the whole of the finger, enlarge the extremity of the hole and ; 
round it carefully, when there will be a very correct represen- ! 
tation of the tunnel formed in the rock. 
Granting that the snail really does form the burrow, we have 
still to discover the mode of working. Mr. Hancock says that 
the foot, which corrodes the rock and renders it easy to be 
