62 
STRANGE DWELLINGS. 
however, retain this form for more than six and thirty hours, but 
undergoes a further process of development, and is then fur- 
nished with a distinct apparatus for swimming and crawling. 
It also possesses rudimentary eyes, and in that portion of the 
body which may be considered the head, there are organs of 
hearing resembling those of certain molluscs. When it has 
passed its full time in this stage of development, it fixes upon 
some favourable locality, and then undergoes its last change, 
which transforms it into the wormdike mollusc with which 
naturalists are so familiar. 
The ravages committed by this creature are almost incredible. 
Wood of every description is devoured by the Ship worm, whose 
tunnels are frequently placed so closely together that the parti- 
tion between them is not thicker than the paper on which this 
account is printed. As the Teredo bores, it lines the tunnel with' 
a thin shell of calcareous matter, thus presenting a remarkable 
resemblance to the habits of the white ant When the Teredos 
have taken entire possession of a piece of timber, they destroy 
it so completely, that if the shelly lining were removed from the 
wood, and each weighed separately, the mineral substance would 
equal the vegetable in weight. 
The Shipworm has been the cause of numerous wrecks, for it 
silently and unsuspectedly reduces the plankings and timbers 
to such a state of fragility, that when struck by the side of a 
vessel, or even by an ordinary boat, large fragments will be 
broken off. I have now before me two specimens of ‘ worm- 
eaten ’ timber, one of which is so honey-combed by this destruc- 
tive mollusc, that a rough grasp of the hand would easily crush 
it. Yet this fragment formed part of a pier on which might have 
depended a hundred lives, and which was so stealthily sapped 
by the submarine miners, that its unsound state was only dis- 
covered by an accident. 
Another species of the same genus, Teredo corniformis , is 
remarkable for the locality in which it is found. This curious 
mollusc burrows into the husks of cocoa-nuts, and other thick 
woody fruits which may be found floating in the tropical seas. 
In consequence of the locality which it selects for its habitation, 
