CHAPTEE V. 



BURROWUiTG MOLLUSCS. 



The BoiiiNG Snail of the Bois des Eochea — Opinions as to its method of 

 burrowing — Shape of the tunnels — Solitary habits of the Snail — The Piddock, 

 its habits and appearance— Structure of the Shell, and its probable use — 

 Mi'.thod of burrowing — Use of the Piddock and other marine burrowers — The 

 balance of Nature preserved— The Wood-bober and its habits — The Date 

 Shell — Its extraordinary powers of tunnelling — The Kazor Shell — Its locali- 

 ties and mode of life— The Flask Shell and the 'Watebixg-Pot Shell — The 

 Shipwokm — 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 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 and wood. Even the 

 hard limestone and sound heart-of-oak timber cannot 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 innu- 

 merable burrows of these molluscs. 



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 

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

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

 ing 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 Eoches, 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. 



