386 
MOLLUSCA. 
Fig. 195. — Cineras Crauchii. 
posterior margin to that of the opposite valve : these five pieces cover the whole of the cloak. From the place 
where the ligament should he springs the fieshy peduncle. A strong adductor muscle unites the two valves near 
their beaks. The mouth of the animal lies concealed behind them, and the posterior 
end of the body, with all its little articulated feet, comes out a little further down, 
between the first four valves. The widest spread species in our seas {Lepas anatifera, 
Linn.) has got its name from having given rise to a fable of its being the original or 
parent of the Barnacle-goose. They grow attached to rocks, piers, to the bottom of 
ships, &c. We may distinguish the Pollicipes, Leach, which, besides the five prin- 
cipal valves, has several small ones near the pedicle. In some species these valves 
almost equal the primary in size. There is often an odd one opposite the normal 
odd one. \Scalpellum, Leach, consists of thirteen valves, six on each side and one 
dorsal ; and its peduncle is squamose.] Cmems, Leach.— The cartilaginous cloak 
incloses five valves, but of small size, so as not to occupy the whole surface. Otion, 
Leach.— The cloak contains only two very small valves, with three little pieces which 
scarcely merit that name ; and there are two tubular appendages in the shape of ears. 
Tetralismis, Cuv., has only four paired valves encircling the aperture, two being 
longer than the others. The animal is partly contained in the pedicle, which is wide 
and hirsute. They are, in some degree, Balani without a tube. {Lithotrya, Sow., 
is pedunculated like Anatifa, but has, at the base of the peduncle, a shelly appendage 
analogous to the testaceous base of Balanus, and possesses besides a peculiarity not 
to be found in any other genus of this class, that of penetrating stones for its habi- 
tation.] 
The Balanus, Brug,, or Acorn-Shells. 
The principal part of the shell consists of a testacous tube attached to various bodies, the aperture 
of which is more or less closed by two or four valves. This tube is formed of various pieces or com- 
partments, which appear to unloose or separate in proportion as the growth of the animal requires 
additional room. The branchiae, the mouth, the articulated tentacula, and the anal tube, differ little 
from the same parts in the Anatifa. 
In Balanus, properly so called, the tubular portion of the shell is a truncated cone, formed of six outer valves, 
separated by as many inner ones, three of which are narrower than the others. Their base is usually formed of a 
calcareous lamina, fixed to various bodies. The four valves of the operculum close the aperture exactly. The 
rocks, shells, and piers of all our coasts are, in a manner, covered with a species, the 
Lepas balanus, Linn. 
There have been separated from these the Acasta, Leach, whose base is irregular, con- 
vex outwardly, and not fixed ; the greater number live within sponges. [Sowerby reunites 
Acasta to Balanus.] Conia, Blainv., whose shell has only four exterior valves. [On the 
contrary, in the Octomeris, Sow., the pieces or valves amount to eight.] Asema, Ranz., 
whose shell has no well-marked exterior valves. Pyrgoma, Sav-, whose shell forms a very 
depressed cone, with only a very small aperture, almost as in a shell of the Fissurella. 
Ochthosia, Ranz., which have only three outer valves, and a bivalved operculum. Greusia, 
Fig.i 96 .-B.spinosus. ^ bivalved operculum. M. de la Lamarck sepa- 
rates, under the name of Coronula, the depressed species in which the 
valves are loosely cellular ; and under that of the species which 
form an elongated cone, but narrowest at the base, and girded with rings that 
mark the successive epochs of its growth. There are species of both genera 
which plant themselves on the skin of Whales, and penetrate into their lard. ^§ili 
Diadema, Ranz.— The shell is almost spherical, and has only two small 
valves, almost concealed in the membrane that closes their operculum. The i 97 ._conia radiata. 
opercula do not shut the aperture entirely without the aid of the mem- . 
brane that unites them. They also live upon Whales ; and we often find Otions attached to their surface. 
