53 



CHAPTER V. 



BURROWING MOLLUSCS. 



The Boring Snail of the Bois des Roches — Opinions as to the method of 

 burrowing— Shape of the tunnels— Sohtary habits of the Snail — The Gaper 

 Shell— The LimpE:T— The Piddock, its habits and appearance— Struc- 

 ture of the Shell, and its probable use — Method of burrowing— The Date 

 Shell— Its extraordinary powers of tunnelling — The Wood-borer and its 

 habits— The Razor Shell — Its localities and mode of life — TheSniPWORM 

 — Its appearance when young and adult — Its curious development — Its 

 ravages — Its value to engineers. 



Ill fitted as the Molluscs seem to be for the task of burrowing, 

 there are several species which are able not only to make their 

 way through soft mud, or into the sandy bed of the sea, but to 

 bore deep permanent tunnels into stone or wood. Even the 

 hard limestone and sound heart-of-oak timber cannnot defy 

 these indefatigable labourers, and, as the sailor or the dweller 

 on the coast knows full well, the rocks and the timber are often 

 found reduced to a mere honey-combed or spongy texture by 

 the innumerable burrows of these molluscs. 



There is now before me a piece of very hard calcareous rock, 

 in which are bored several deep lioles, large enough to admit 

 a man's thumb, and remarkably smooth in the interior, the 

 extremity being always rounded, Indeed, if a hole were made 

 in a large lump of putty by putting the thumb into it and 

 turning it until the sides of the hole became smooth, a very 

 good imitation of these miniature tunnels would be produced. 

 This fragment of stone was taken from a litde wood in Picardy, 

 called Le Bois des Roches, on account of the rocky masses that 

 protrude through its soil, and was brought to England by Mr, 

 H. J. B. Hancock, who kindly presented it to me. 



