80 THE UNIVERSE 



CHAPTEE III 



STONE-BORERS AND WOOD-BORERS. 



We have just seen how invisible architects make the 

 depths of ocean bristle with forests of coral or layers of 

 madrepore; we have now to busy ourselves about workmen 

 of another class : the true miners, who build nothing, but 

 instead hollow out for themselves vaults in the submerged 

 rocks. Their ceaseless, and as yet inexplicable, toil assails 

 and pierces deeply into the most compact stones. We are 

 astonished, in splitting marble, to find living shells in the 

 midst of blocks which the chisel of the sculptor only 

 cuts with difficulty. 



The most renowned of the stone-borers we are acquainted 

 with, the Pholades, ordinarily scoop out their abodes in 

 the calcareous rocks of our shores. They are thin, white 

 shells, their valves l:)eing elegantly ornamented with pro- 

 jecting lamellfe or symmetrically arranged j)oints. Their 

 two ends are opened wide. From one issue the respir- 

 atory and nutritive tubes, which lengthen themselves out 

 from the bottom of the cavity inhabited hj the mollusc, in 

 order to pump up the sea-water with its myriads of ani- 

 malcules. From the other, still more open, proceeds the 

 foot, a thick, powerful, living sole, intended beyond doubt 

 to play a great part in the life of the solitary animal. 



There are pholas-hunters just as there are prawn-fishers. 

 The former can be distinguished with singular facility at a 

 very great distance, owing to the brilliant whiteness of their 



