40 
that it is worn away. Tf the worm has been long in the shell, the 
grooves formed are deep, and the longer they remain the deeper 
they become. When measured from the outside inwards they are 
longer and more tubular ; but this is owing to the fact that the 
growth or increase in the size of the shell forces the entrances 
further outwards and upwards, or downwards, as the case may 
be, according to whether it is the upper or lower valve which is 
affected. Ultimately the openings have the keyhole-like aspect 
which look as if they had been bored, but which, if carefully 
examined, will show that they have passed through the various 
phases before mentioned, becoming shallower inwards and 
ceasing to be grooved at all . With regard to the worm boring 
into limestone, shale, &c., mentioned by English writers, 1 
think it is quite possible that a young worm may take possession 
of a small depression, and as it grows gradually enlarge it by 
its constant movements in and out, until it has formed its 
tube in the same Such tubes may serve for a succession of 
generations, being still increased in size by each occupant, as is 
the case with some of our sea-urchins which form holes in the 
sandstone of Port Jackson. But still there would be an absence 
of boring in the sense used with reference to this worm. Pro- 
fessor McIntosh, in the Ann. and Mag. of Nat. Hist., vol. 24, 
ser.^1868, p. 278, speaks of its boring into any shell that is thick 
enough to be bored. 
The Remedy. 
There are several ways in which to deal with the worms, with 
a view to their destruction. Those which I am about to give are 
the result of direct experiment, and if carried out in a proper 
manner, will prove effectual. When I returned to Sydney, after 
my fortnight’s sojourn at Newcastle^, I brought back a large 
quantity of diseased oysters. These I experimented on in various 
ways during a period of two months, having them under obser- 
vation daily during the whole of that time. Some of the worst 
cases were placed in fresh water, which had the effect of killing 
the worms and some of the oysters ; the latter were no doubt 
killed by the putrescent germs developed in the mud after the 
death of the worms. Others which were kept without water for 
fourteen days, were afterwards placed in salt water for several 
days, and in all cases the worms were destroyed, whilst the 
oysters appeared to be in a healthy condition. Some which were 
kept in an extempore aquarium for over two months, were 
cultivated until the whole of the worms had died out. This 1 
attribute to the water supplied, not on account of its being bad, 
but from the fact that it was moderately clear and free from 
mud, which seems so essential to the life of the worm. 
From the above series of experiments we may conclude that 
placing the oysters in fresh water for a few days will destroy the 
