328 MR. A. HANCOCK ON A BURROWING BARNACLE 
the fine specimens of Cliona gorgonioides which it contained. 
Since then, I have got this Cirripede alive from the boats at Cul- 
lercoats, also in Fusus antiguus: it has likewise occurred in Buc- 
cinum undatum, from the same locality. And on breaking an 
old specimen of the former, which has been many years in my 
collection, it was found to have been extensively attacked by this 
novel parasite. Indeed almost every dead specimen of the large 
fusus, brought in by the fishermen, from deep water, is more or 
less affected by it; and the only wonder is that it should have 
remained so long undetected. This perhaps may be explained 
by the fact that this animal only attacks dead shells, and always, 
so far as I have yet observed, from the inside, so that it is 
scarcely to be seen until the shell is broken. The columella is 
the chief seat of the ravages of this creature, though the sides of 
the whorls do not by any means escape, especially if the indi- 
viduals are numerous. When quite young they enter the sound 
shell, and as they grow, enlarge their residence, which is always 
of the exact size and form of the tenant. 
It is interesting to remark how completely this animal, toge- 
ther with Cliona, destroys the shells of the larger mollusks of 
our coast. Cliona enters by the outer surface of the living shell, 
and rapidly spreads over the whorls; but it is not, until after 
death, that the inner surface becomes much affected by it. Then 
this Cirripede commences its ravages on the columella, which it 
soon deprives of more than half its substance, and afterwards so 
reduces it and the inner surface of the whorls, that this once 
secure retreat of the mollusk, losing all power to resist external 
forces, speedily becomes a crumbling ruin. 
Little is to be seen externally,—a small slit in the shell or 
matrix marks the position of the head. This slit, which is one- 
eighth of an inch long, is rounded and gradually enlarged towards 
one end, and tapers to a tolerably fine point at the other, which 
is generally a little bent. At this extremity the shell is mostly 
stained of a reddish hue—the stain being well-defined and of an 
ovate or fan-like form, increasing in size for about zths of an 
inch backwards, and having a few pale radiating lines, which 
converge towards the slit; on these lines there are a few minute 
