CAUSES OF DECAY AND DESTRUCTION OF TIMBEE 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 
Photo hi/] . [-•!• O'uhridge. 
Fig. 36.— Worm-eaten Timber. 
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 
