608 



THE PIDDOCK AND THE SHIP- WORM. 



mou species popularly called Piddock, and found in profusion along 



the seacoast. 



The common Piddock may be found in vast numbers m every sea- 



The Common Razor-shell {Solen vagina). 

 covered chalk rock, into which it has the gift of penetrating so as to 

 })rotect itself from almost every foe. 



Mr. Woodward remarks, very justly, that the "condition of the Pho- 



lades is always related to the na- 

 ture of the material in which they 

 are found burrowing ; in soft sea- 

 beds they attain the largest size 

 and greatest perfection, whilst in 

 hard, and especially gritty, rock 

 they are dwarfed in size, and all 

 prominent points and ridges ap- 

 pear worn by friction. No notice 

 is taken of the hypothesis which 

 ascribes the perforation of rocks, 

 etc., to ciliary action, because, in 

 fact, there is no current between 

 the shell, or siphon, and the wall 

 of the tube." As soon as the ani- 

 mal has completely buried itself 

 it ceases to burrow, and only pro- 

 jects the ends of the siphon from 

 the aperture of the tunnel. 



Allied to the preceding mol- 

 luscs is the Ship-w^orm, so called from its depredations on the bottoms 

 of ships and all submerged wooden structures ; it is found in most seas, 

 and on our own 

 coasts works fear- 

 ful damage by 

 eating into piles, 

 planks, or even 

 loose wood that 

 lies tossing about 

 in the ocean. 



Wlien removed from the tube the Ship-worm is seen to be a long grav- 

 ish-white animal, about one foot in length and half an inch in thickness. 



I'uK PiDDocK {Pkolas dactybm). 



The Ship-worm [Teredo navalis). 



