104 
THE SALT-WATER AQUARIUM. 
Mussels are bivalve mollusks, living in strong shells of an oblong trian¬ 
gular form, terminating in a point. The head of the animal is situated to¬ 
ward the point near the 
hinge. Mussels abound on 
rocks, and the piles of piers 
and quays, to which they at¬ 
tach themselves by bunches 
of strong fibres. When they 
move, which they sometimes 
do, they thrust a tongue-like 
foot out of the shell, and, 
fixing it some way in advance, draw themselves onward. The Mussel should 
always have a place in the Aquarium. It is a very hardy creature, and 
although familiar to every one, is by no means an uninteresting object of 
contemplation. It especially commands our admiration, whenever, by means 
of its byssus (formed by a number of silk-like threads), it anchors itself to 
the sides of the tank, becoming so fixed that it would take pretty consider¬ 
able force to dislodge it. 
Barnacles are often to be found 
upon the sea-shore, drifted thither 
upon the wood of a wrecked ship, or 
other floating body. We have seen 
a ship’s mast, which had long driven 
about at sea, literally covered with 
them. They are often found cling¬ 
ing in great numbers to the bottoms 
of ships, greatly retarding their speed. 
They grow or live in clusters, each 
barnacle consisting of a membrana¬ 
ceous branch or arm, which is fixed 
to some body, the animal being in¬ 
vested with compressed shells, at¬ 
tached to the pedicel. The larger 
barnacles cluster with the smaller in 
the same group, and form bunches 
of various sizes. They are fur¬ 
nished with many tontacula, with 
which they gather their food. 
When ships covered with the Bar¬ 
nacle arrive in our ports, the Barna¬ 
cles are eagerly scraped off by men, 
who take them for sale as marine curiosities, or who make their delicate 
white porcelain-like shells into some kinds of fancy shell-work. The Bar¬ 
nacles themselves are eaten on some coasts of Africa, where they are very 
abundant. The shell of this animal is at the end of a long fleshy stalk, 
