EOCK-BOIIEES. 61 



to support the weight of the frond; and thus the plant is 

 detached and driven on shore hy the waves. 



. "And so the forest tall that growetli, 



Uiulerneath the waters clear, 

 Does the little woodmau mollusk, 



Level every year; 

 From small causes, great results — 



Teaching you to persevere." 



ROCK-BOHEES. 



The fitmily Pholadce comprises a group of mollusks, the 

 horing habits of which have long been known; they penetrate 

 wood, hard clay, chalk, and rocks, and devastate the labours 

 of man; they attack the hulls of ships, the piles which form 

 the foundations of piers and break- waters, and they force them- 

 selves upon our attention by the loss of property, as well as 

 of life, which results from their hidden depredations. Of 

 this famil}', those belonging to the genus Pholiis may be more 

 especially likened to the Edomites of Scripture, because they 

 take up their abode in the rock, and hollow out for themselves 

 dwellings therein. AVith a shell as thin as paper, and brittle 

 as glass, the wonder is how these Eock-borers work their 

 way into and through hard stones. Some naturalists assert 

 that they effect this by means of an acid which decomposes 

 the substance of the rock, and renders it soft; others, that 

 the animal keeps turning round and round like an instrument 

 called an auger, and so gradually rasps away the surface of 

 the stone with the angles of its shell, but we question whether 

 the shell would not be worn out first in such a process. 

 The generic name of these "stone-piercers," comes from the 

 Greek word Pholeo — to hide, and the rocky chambers which 

 they hollow out for tliemselves, are as snug hiding-places as 

 can well be imagined; yet, hov/ever deep they may go into these 

 glooitiy caverns, as we should be apt to suppose them, they 

 need not be in darkness, for it appears that these Pholades 

 emit a most remarkable light, whether phosphorescent or not 

 does not appciir to be determined; so strong is it, that it is 



