114 HOMES WITHOUT HANDS. 



CHAPTER V. 



BURROWING MOLLUSKS. 



The Boring Snail of the Bois des Roches. — Opinions as to its Method of Burrow- 

 ing. — Shape of the Tunnels. — Solitary Habits of the Snail. — The Piddock, its 

 Habits and Appearance. — Structure of the Shell, and its probable Use. — Method 

 of Burrowing. — Use of the Piddock and other marine Burrowers. — The Balance of 

 Nature preserved. — The Wood-borer and its Habits. — The Date Shell. — Its 

 extraordinary Powers of Tunneling. — The Razor Shell. — Its Localities and 

 Mode of Life. — The Flask Shell and the Watering-pot Shell.— The Ship- 

 worm. — Its Appearance when Young and Adult. — Its curious Development. — 

 Its Ravages, and the best Method of checking them. — Its Value to Engineers. 

 — The Giant Teredo. — Form, Dimensions, and Structure of the Shell. — How 

 and where discovered. 



Ill fitted as the Mollusks seem to be for the task of burrow- 

 ing, 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 and wood. Even 

 the hard limestone and sound heart-of-oak timber can not defy 

 these indefatigable laborers, 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 mollusks. 



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

 in which are bored several "deep holes, large enough to admit a 

 man's thumb, and remarkably smooth in the interior, the extrem- 

 ity 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 little 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. 



In the winter time, each of these holes is occupied by a speci- 

 men of the Helix saxicava, a small snail, closely resembling the 

 common banded snail of our hedges {Helix nemoralis), and it is 

 thought that the holes are excavated by the snail which inhabits 



