72 THE UNIVERSE. 



CHAPTER 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 enables 

 them to pierce 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 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 being elegantly ornamented with projecting 

 lamellae or symmetrically arranged points. Their two ends 

 are opened wide. From one issue the respiratory and nu- 

 tritive tubes, which lengthen themselves out from the bot- 

 tom of the cavity inhabited by the mollusc, in order to 

 pump up the sea-water, with its myriads of animalcules. 

 From the other, still more open, proceeds the foot, a thick, 

 powei fal, living sole, intended to play a great part in the 

 life of ihe 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 



