EXCAVATORS. 351 



quite incredible, and they belong to different families 

 of the animal kingdom. Among the most active 

 and powerful we would mention the date-fish, and 

 many worms, of which the Serpula is the largest, and 

 most destructive, inasmuch as it extends constantly 

 through the living part of the coral stems. On the 

 loose basis of a brain-coral, measuring less than two 

 feet in diameter, we have counted not less than fifty 

 holes of the date-fish, some large enough to admit a 

 finger, besides hundreds of small ones made by 

 worms. But however efficient these boring animals 

 may be in preparing the coral stems for decay, there 

 is yet another agent perhaps still more destructive, 

 we allude to the minute boring-sponges, which 

 penetrate them in all directions, until they appear at 

 last completely rotten through." This last remark, 

 as to the boring sponges, should be borne in mind, 

 coming as it does from such an authority, when we 

 advert to the diversity of opinion, still existing, as to 

 the capacity of sponges as excavators. 



The boring annelids, or worms, have never had 

 their penetrating powers called in question, so that 

 it may be conceded that they are ever industriously 

 at work, in drilling their sinuous galleries, not only 

 through the dead stems of coral, but also into the 

 hard rock. They belong to numerous species, some 

 of them classed with the tube-forming annelids, from 

 their habit of lining their excavations, so as to con- 



