40 LIVING LIGHTS. 



CHAPTER VI. 



LAMP SHELLS. 



IN all the forms previously mentioned, the phosphorescence 

 is conspicuous; but in the little bivalve Pholas it is almost 

 hidden. The shells of the family Pholadidce are noted for 

 their boring habits ; penetrating into the hardest stone, as 

 granite and gneiss, literally entombing themselves, as shown 

 in Plate VII., Fig. 1, which represents a section of a block of 

 granite into which the little animals have penetrated. How 

 they can perform such a work, is something of a mystery ; 

 but the foot, which is provided with a hard dermal protection, 

 is probably the instrument used by the miner. 



The most remarkable evidence of their work, according to 

 Figuier, — though it is fair to say he has been disputed, — is 

 seen in the Temple of Serapis on the Pozzuolan coast, where 

 the pillars are perforated with holes, which this author claims 

 were made by the Pholas,^^ when by a sinking of the crust the 

 pillars were under water ; the columns, by a reverse motion, 

 having now re-appeared from the sea, bearing the evidences of 

 their submersion. 



As if to still further carry out the idea of the miner, the 

 animal bears its own light, which, though vivid, could but 

 little more than illumine the stony prison into which the 

 Pholas has willingly ensconced itself. In Borneo, a fresh- 



