306 Mr. A. Hancock on a Burrowing Barnacle 
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 sht in the shell or 
matrix marks the position of the head (Pl. VIII. figs. 1 & 2). 
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 (PI. VIII. 
figs. 1 & 2.a)—the stain being well-defined and of an ovate or 
fan-like form, increasing in size for about 5;4ths of an inch back- 
wards, and having a few pale radiating lines, which converge 
towards the slit ; on these lines there are a few minute punctures 
irregularly distributed ; but whether for functional purposes, or 
merely accidentally resulting from the close approximation of 
the animal to the surface, could not be determined : they are not 
unfrequently partially closed up with calcareous matter. 
The stain is caused by the animal appearing through, which 
les immediately below the surface of the matrix. This must be 
broken before the animal (PI. VIII. figs. 3, 4, 5) can be removed, 
and then it is found to be ;4,ths of an inch long, and 52,ths of an 
inch wide at the broadest part, of an irregular ovate form consi- 
derably depressed behind, 6, where it expands into a broad circular 
disc ; and narrow and compressed in front, a, forming a sort of 
produced neck or head with a longitudinal slit, c’, on the upper 
surface ;—the general form resembling considerably a Roman 
lamp, the slit representing the orifice for the passage of the wick. 
The produced portion or head corresponds to the valvular part of 
the pedunculate Cirripede, and contains the body and arms or 
feet,—the slit beimg analogous to the usual opening for the pas- 
sage of these prehensile organs: there are, however, no shelly 
plates whatever, the mantle being soft, fleshy and highly con- 
tractile, having the surface distinctly marked with fine longitu- 
dinal muscular fibres below; this part arches deeply into the 
matrix, and joms rather abruptly the under surface of the de- 
pressed disc-like portion of the animal considerably behind the 
posterior end of the longitudinal slit. The margins of this slit 
are perfectly straight, thickened, and have somewhat the appear- 
ance of horn, but cannot be considered as forming distinct plates, 
though they compose, as it were, two valvular lips (figs. 3 & 5 c), 
Pas ys ee 
