54 STRANGE DV/ELLINGS. 



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 

 molluscs when the rocks in question formed part of the ocean 

 bed, and that the snails merely inhabit the ready-formed holes. 

 Mr. Pinkerton upholds this opinion, and states that at least 

 three other species of helix possess similar habits, the garden 

 and the banded snail being among the number. 



I have compared the burrows of the mollusc, which we will 

 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 finger into the hole as far 

 as the second joint, and repeat the process. Now introduce 

 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 

 it must do so by means of an acid secretion proceeding from 

 the foot, which corrodes the rock and renders it easy to be 



