TEREDO SHIP WORM. 133 



destructive to our shipping. It readily enters the 

 stoutest timbers, and ascends the sides of the 

 loftiest ships, most insidiously destroying them. 

 When the hulk of a ship is any time under 

 water, the Teredines appropriate it to their own 

 use, and soon commence the work of destruction, 

 They begin with the softest part, and at first 

 the apertures they make are so small as scarcely 

 to be perceptible. Their manner of carrying on 

 their labour is remarkable : they are careful 

 never to intrude upon the habitation of a neigh- 

 bour, and even where a piece of wood has been 

 so excavated as to resemble a honeycomb, no 

 communication or passage has been discovered 

 between the perforations, though often separated 

 only by the slightest lamina of wood. They 

 always bore in the direction of the grain of the 

 timber ; if they meet in their course with another 

 shell or knot, they make a turn ; when the obsta- 

 cle is small, they wind round it, and then proceed 

 onwards, but when large, rather than continue 

 any distance across the grain, they make a short 

 turn back in the form of a syphon. The attacks 

 of this insidious enemy have not been confined 

 to shipping ; our dock yards also bear sad testi- 

 mony to their work of devastation. In Holland, 

 where the inroads of the sea, and of the great 

 rivers by which that country is intersected, 

 have been restrained with immense labour by 

 dykes, the Teredines have proved very destruc- 

 tive, piercing and even destroying the piles 

 which sustained them. 



