THE SHIP WORM. 63 



it cannot proceed in one direction for any great distance, and 

 is obliged to make its burrows in a crooked form, which has 

 earned for the creature the specific title of corniformis, or horn- 

 shaped. Fossil woods are often found perforated with these 

 burrows. 



Destructive as it may be, the Shipworm will ever be an object 

 of interest to Englishmen, inasmuch as its shell-lined burrow 

 gave to Sir I. Brunei the idea which was afterwards so efficiently 

 carried out in the Thames Tunnel. And, though from the 

 alteration of surrounding circumstances, that wonderful monu- 

 ment of engineering skill has not until of late been so practi- 

 cally useful as was anticipated, it has proved of incalculable 

 value as pioneer to the numerous railway tunnels of this and 

 other countries. 



