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 neighbour, 

 and even where a piece of wood has been so ex- 

 cavated as to resemble a honeycomb, no commu- 

 nication 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 obstacle 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 insi- 

 dious enemy have not been confined to shipping ; 

 our dock yards also bear sad testimony 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 res- 

 trained with immense labour by dykes, the Tere- 

 dines have proved very destructive, piercing and 

 even destroying the piles which sustained them. 



