54 FEBRUARY. 



ample ivory-like shells, which yet cannot half contain 

 the whiter flesh of their ampler bodies, and the long 

 stout yellow siphons that project from one extremity, 

 reaching far up the hole towards the surface of the 

 rock. 1 



We lift one from its cavity, all helpless and unresist- 

 ing, yet manifesting its indignation at the untimely 

 disturbance by successive spasmodic contractions of 

 these rough yellow siphons, each accompanied with a 

 forcible jet d'eau, a polite squirt of sea- water into our 

 face ; while, at each contraction in length, the base 

 swells out. till the compressed valves of the sharp shell 

 threaten to pierce through its substance. 



Strange as it seems, these animals have bored these 

 holes in the stone; and they are capable of boring in 

 far harder rock than this ; even in compact limestone. 

 The actual mode in which this operation is performed 

 long puzzled philosophers. Some maintained that the 

 animal secreted an acid which had the power of dissolv- 

 ing not only various kinds of stone, but also wood, 

 amber, wax, and other substances, in which the excava- 

 tions are occasionally made. But it was hard to imagine 

 a solvent of substances so various, and to know how 

 the animals' own shells were preserved from its action ; 



1 Pholas dactylus ; the principal figure in Plate vi., represented as ex- 

 posed in its burrow by the splitting off of a portion of the limestone rock. 



