996 Marvels of the Universe 
almost be considered to be an elongated variety of the Wood Piddock, so akin is it both in formation 
and characteristics ; and this is especially true of it in its early stages. Then it possesses a well- 
formed but very round clasp shell, from the hinder margin of which protrude the long siphons 
enclosed in a stout leathery tube. Near the junction of the siphons with the body proper the 
mantle is developed into a frill with a heavy fringe of cilia. 
This stage in the life-history of the Teredo is shown on the lower right-hand side of the full- 
page illustration. The foot is protruded, for the creature is ready to settle down and take up 
the final stage of its existence; that is, as an inmate of a burrow such as is shown perforating 
the wood. When it has found a suitable place it commences to bore, always with the grain of 
the wood, and then to line its burrow with a kind of cement which is exuded from the mantle 
and as it hardens becomes like porcelain. But soon it will undergo a very decided transforma- 
tion; for once again if we look to our illustration (page 997) we shall see that the globular 
shell and fringed mantle have entirely 
disappeared and, instead, we have the 
long thin ‘‘ worm” shaped like a nail 
with a rounded head, and all that is 
left of the shell are two thin, chalky 
shields. These have been drawn on a 
black background in order to show 
their peculiar shape more distinctly. 
It should be noted that two distinct 
types of Teredo—the Common Ship- 
worm and the Norwegian Ship-worm— 
shells are shown, for the species of this 
strange family are numerous. The 
larger of these two is the Norwegian 
Ship-worm, whose siphons may be 
developed to more than a couple of 
feet in length. 
In likening the Ship-worm to a 
nail which works its way into a plank, 
the simile of a well-known writer has 
been used; but if we adopt this 
description we must remember that 
the nail bores into the wood head 
foremost. The exact means employed 
to effect ingress into the hard material is not known, but as far as we can tell all the boring 
is done by the action of the foot. Possibly, also, the double “ tail’? already mentioned, of 
which each branch terminates in a paddle-shape valve or pallet, is used to enlarge and smooth 
the sides of the burrow. The Teredo does not, as is popularly supposed, feed on the wood which 
it excavates. All this is passed out as débris, while it nourishes itself on the microscopic life of 
the water. 
THE SHIP-WORM’S WORK. 
Cross-section of a piece of timber tunnelled by the Ship-worm. 
Although the wooden ship has almost gone, and of those that remain patent compositions and 
copper sheathing have rendered the majority useless to the Ship-worm, there is little likelihood 
that he will disappear from the high seas. He may have to change his name as being no longer 
appropriate, but it is probable that he will always find floating logs and planks to riddle ; and there 
are always temporary timber structures about our docks and quays that will serve to keep a remnant 
of the race, from which in due course—who knows ?—may be evolved a mollusc that can bore steel 
plate ! 
