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. 
