TEREDO. 133 



testaceous^ and annulated or divided into ring-like 

 segments ; it is highly polished inside. The larger or 

 inner extremity is concave ; the other extremity is 

 conical. Adanson considered this appendage to be a 

 part of the shell. The Teredo is gregarious^ although 

 not of a sociable habit ; and, in the prosecution of its 

 burrowing operations, it is actuated by a conscientious 

 anxiety not to infringe on its neighbour. When a 

 collision is imminent, it secretes a cup-shaped dome or 

 plug in front, of a thinner texture than the rest of the 

 sheath; and it shuts itself up. Sometimes it makes 

 several of these outer walls, one after another. Young 

 and old equally do this. It then, being unable to eat 

 its way through the wood and thus procure a supply of 

 food, dies of starvation, preferring suicide to the alter- 

 native of invading and injuring its companions ! This 

 sacred duty, he assures us, is performed with almost a 

 reverential care. He evidently considered his '^ hero '' 

 (as he called the Teredo) the pink of chivalry and 

 honour. The wood is often so completely honeycombed, 

 that the party-walls which separate the burrows of the 

 Teredijies consist of mere films. Rousset compared 

 the wood in this state to an extremely light and porous 

 kind of rusk or biscuit. Sellius stated truly the object 

 and mode of the curious dome-like fabrication which I 

 have above described ; but there was no foundation for 

 the consequences pictured by him, except in his fertile 

 imagination. The progress and further growth of the 

 Teredo would necessarily be arrested by the barrier 

 which it had interposed in front. But that was all. 

 The food of the Teredo consists entirely of minute or- 

 ganisms, that are introduced with the water into the 

 incurrent or branchial tube ; and it does not consume 

 the wood as any part of its nutriment. Nor do I be- 



