150 



SAXICAVOUS MOLLUSCA. 



of its submersion. At the height of ten feet above tlie base 

 of the three standing pillars which remain, and in a position 

 exactly corresponding in all, is a zone of six feet in height,* 

 where the marble has been scooped into cells by these 

 mollusca (Fig. 26). The holes are to the depth of four 



Fig. 2G. 



inches ; and it is observed that the nodules of quartz and 

 feldspar, which sometimes occur in the hard limestone of the 

 pillars, are untouched. In what manner this temple was 

 submerged and again left dry has much puzzled and per- 

 plexed philosophers, and the discussion is, fortunately, 

 beyond our province ; but it becomes us to inquire by what 

 means shell-iish make these holes, for which, apparently, 

 they are most unfit. 



The point has been much debated, and it seemed so hard 

 to solve, that Rondeletius saw nothing for it but to suppose 

 that the sea-water, lodging in the rocks, was itself trans- 

 formed into Pholades and other saxicavous mollusca; and 

 other philosophers, as Mr. Bingley good-naturedly calls 

 them, were driven to the belief that they entered the rock 

 while it was yet in a soft state, which afterwards hardened 

 by degrees around them. Two explanations of the process 



* Spallanzani says that the height from the ground is about nine feet, 

 and that the perforated band is only " about two feet in breadth." Two 

 species of Mytilus or Modiola and " other litiiophagous worms " have worked 

 to produce it. — Tntv. in the Two Sicilies, i. 84, 85. 



