hi-> 



THE UNIVERSE. 



It is, however, clear that among the Pholades living in 

 the calcareous rocks of our shores, the strongly made foot 

 undertakes the task in question. By its ceaseless move- 

 ments this fleshy sole, little by little, wears away the rock 



31 Dactyloid Pholailes in their Holes— PAo^as dacii/lus. 



Avhich the water has softened. In fact, the rock, which 

 is so hard in its dry state, is on the contrary very soft 



awa)', but because we see certain stone-eating mullnscs preserve their eiiiJenuis 

 in the midst of the coral rocks and chalk into which they penetrate. As to the 

 pholads of our shores, I have proved the fact by demonstrating that all the in- 

 terior of the hole, on a level with the shell, is covered with a layer of mud, wliicli 

 would prevent the action of its spines npon the projecting points Lif the stone. 



It was M. Fleuriau de Bellevue who thought that the pholads make their way 

 into stone by means of an acid, and as he had noticed that these molluscs are 

 luminous in the dark, he drew the inference that the fluid produced by them was 

 probably phosphorous acid. This opinion is inadmissible, and the phenomenon 

 mentioned by the able observer in question is beyond all doubt only due to the 

 luminous Microzoa so abundant in the sea, and which ];roduce its phosphor- 

 escence. 



