754 
PROCEEDINGS OF SECTION H. 
wood sufficiently soft and porous for its purpose, it pauses, attacks the 
ligneous substance, and soon produces a little depression or opening, 
which will be the entrance to the future tunnel.” 
Each hole made by the animal is lined with a calcareous deposit, 
and the end of the hole where the Teredo is working is rounded off 
hemispherically. I have found that a period of six months’ immersion 
of timber in the river Fitzroy is sufficient not only for the entrance 
of the Teredo but also for doing a considerable amount of damage to 
any timber structure. I have also noticed that the zone of its 
operations here is generally from a point midway between high and 
low water marks downwards to the bottom of the timber. Some 
authorities state that the animal does not work below the level of the 
mud at the river bottom, but I have observed piles eaten by the Teredo 
to a depth of 5 feet below the mud-line of the river bottom, although 
I believe it always enters the timber above mud-level. 
The kind most prevalent in the river Eitzroy is the Teredo 
gig ant ea ; it grows to a length of about 30 inches, and about i-inch 
in diameter. The anatomy of the Teredo has not yet been fully 
determined, and there has also been uncertainty about the method 
of its boring operations. So far the animal appears to have preserved 
this “trade secret” of its method of penetrating into and tunnel- 
ling through the hardest known kinds of timber. The question 
which has hitherto been left as au undecided one by naturalists 
is as to whether the Teredo actually bores into the timber by the 
aid of its shells with an auger-like action, or by means of some 
solvent secreted by it acts on the wood at the end of the tunnel, 
making it soft and capable of being gouged or scooped out by the shells 
with which it is provided. Osier says, “ It bores by means of its shells, 
fixing itself by the surface of the foot, which it uses as a sucker, and 
then rasping the wood with the rough front edges of the shell valves.” 
A\ T . Thompson holds “ that it works by means of a solvent secreted 
from the surface of the animal.” Albany Hancock thinks “the 
excavating power of the Teredo is due to siliceous particles embedded 
in the anterior portion of the integument in front of the valves. ” This 
has been denied by others, who discredit the idea of the existence of 
these sili cions particles. .Jeffreys believes that “the foot is the 
organ by which it bores.” I have been for some time engaged in 
observations of the Teredo with a view to ascertaining, if possible, the 
secret of its working, but so far have not been able to settle the point 
to my complete satisfaction. I intend to continue my observations 
further, and note the matter in passing, in the hope that some members 
of the Biology Section of the Association may be able to join in the 
future investigation of this subject. 
THE RAVAGES OF THE TEREDO. 
The destructive work of this animal is very frequently under the 
notice of the shipbuilder and the civil engineer; and from what I have 
seen of its ravages in different parts of Australia, 1 consider the 
economic aspect of the habits of the Teredo is one of very great 
great importance. The destruction of valuable river and harbour works 
built of timber is very great, and the loss throughout Australia from 
this cause must amount to a considerable sum of money. As an 
