CAUSES OF DECAY AND DESTRUCTION OF TIMBER 263 



produced by eggs, and is so prolific that the eggs from a 

 single specimen may number a million in one season; they 

 are free swimming in three hours, have a well-developed 

 shell before the end of the day, are very hardy, and nearly 

 all seem to develop to maturity. Its method of operation 

 ' is to bore by means of small and beautifully formed 



I'lllltn I'll] 



FIG. 30. Worm-eaten Timber. 



[A. L. Oubridge. 



Pieces on left and right show the action of the Teredo 

 the latter is from a plank which was in Genoa Harbour for 

 three months. The centre piece shows the work of the 

 Limnoria. 



shells, and it deposits a thin calcareous coating upon the 

 newly cut surface . of the wooden tunnel which it makes, 

 forming an enamelled lining through which the animal 

 can glide backwards and forwards as it expands or con- 

 tracts. It commences operations from the outside by 

 boring across the grain of the wood, and once a short 

 distance within, it generally turns and works parallel to 



