﻿No. 3. PHOLAS. 

 Peirce Stone. Inhabitant an Ascidia. 



The animals of this tribe perforate clay, spongy stones and wood, very young; 

 and as they increase in size they enlarge their habitation, and thus become 

 imprisoned. Before these animals attempt to penetrate stones, they soften them 

 by discharging a quantity of phosphorescent fluid, which decomposes or cor- 

 rodes the substance, as effectually as any chemical solvent, and prepares it for 

 the reception of the shells, which they are enabled to insert in the manner of 

 a screw, the worm being spiral and toothed; the animal then begins to make an 

 entrance with the larger end of the shells, and thus all possibility of return is 

 cut off. They are always found below high-water mark, and a mass of rock may 

 sometimes be seen wholly perforated by them. They have two orifices or 

 openings capable of elongation, in the manner of a proboscis: one of them is 

 supposed to be the mouth, and has the faculty of spouting water: most of them 

 contain a phosphorescent liquor of great brilliancy in the dark, which also 

 illuminates whatever it touches or happens to fall upon. 



The Pholas is so called from the Greek <p&/Xaj, to lurk in cavities, or 

 seek a hiding place. 

 The Pholas dactylus affords the character of nearly the whole tribe. The 

 very extraordinary powers possessed by these animals of penetrating into solid 

 bodies, when compared with their apparent imbecility, have justly excited 

 the astonishment of Philosophers and Naturalists of all ages. When divested 

 of their shell, they are roundish and soft, with no instrument that in the least 

 seems fitted for boring into stones, which they are known to do, or even for 

 penetrating the softest substance. They are indeed furnished with two teeth; 

 but they are placed in such a situation as to be incapable of touching the hol- 

 low surface of their stony dwellings. They have also two corners to their 

 shells, which open or shut at either end; but these are totally unserviceable to 

 them as miners. The instrument with which they perform all their operations, 

 and by means of which they bury themselves in the hardest rocks, is only a 

 broad, fleshy substance, somewhat resembling a tongue. With this soft, yield- 

 ing instrument, while yet young and small, they work their way into the sub- 



