BIVALl'E MOLLUSC A. 331 



require the aid of cooking to render it palatable) would appear in the 

 dark as if they had swallowed phosphorus ; and the fisherman who, 

 in a spirit of economy, supped on this mollusc in the dark, would 

 give to his little ones the spectacle of a fire-eater on a small scale. 



The perforations produced in stone by the Pholads have become 

 important evidence in a geological point of view. In many countries 

 there are evident signs of a considerable past sinking and then up- 

 heaval of the earth. But in no place is the evidence of this clearer 

 than in a monument of high antiquity on the Pozzuolan coast, known 

 as the Temple of Serapis (PLATE XL). 



In speaking of the culture of oysters by the Romans we shall have 

 occasion to mention the disappearance of the Lucrine Lake, and its 

 replacement by an enormous mountain, the Monte Nuovo. Now, 

 Pozzuolo is situated at the foot of Monte Nuovo. We need not add 

 that the whole neighbourhood is volcanic. Pozzuolo touches on the 

 Solfaterra, on the Lake Avernus, and is not far from Vesuvius ; and in 

 the bay is the monument of other days, erroneously called the Temple 

 of Serapis. In reality it was most probably a thermal establishment, 

 established for its mineral waters, although the world has now agreed 

 to call it a temple. 



However that may be, the building has been nearly levelled by the 

 hand of Time, aided by the hand of man; and the ruins now consist of 

 three magnificent marble columns of about forty feet high. But the 

 curious and important fact is, that these three columns, at about ten 

 feet above the surface, are riddled with holes, and full of cavities bored 

 deeply into the marble, and these borings occupy the space of about 

 three feet on each column. The cause of these perforations is no longer 

 doubtful. In some of the cavities the shell of the operator is still 

 found, and it seems settled among naturalists that it belongs to a 

 species of Pholas, although M. Pouchet, a naturalist of Rouen, denies 

 this. "As far," he says, "as I have been able to judge from the 

 fragment which I extracted from this temple, which is destitute of 

 the hinge, it is infinitely more probable that this mollusc is a species 

 of the genus Coralliophaga" In spite, however, of M. Pouchet's 

 scepticism, the mass of evidence is opposed to his theory. 



There are two modes of explaining the fact to which we have called 

 attention. To enable the stone-boring molluscs, which live only in 

 the sea, to excavate this marble, the temple and columns must have 

 been buried several fathoms deep in sea-water. It is only in these 

 conditions that the borers could have made burrows into, and laboured 

 at their ease, in the marble columns. 



But since the same traces of perforation are now visible ten feet 



