E DIODON.

The smaller inhabitants of the ocean are also represented in these
fresh-waters. The little mamayacu, a species of diodon, which in the
ocean attains a foot in length, is found in the Amazon three or four
inches long, of a pretty green colour, banded with black. On being
caught--which it easily is--it becomes in the hand as round as a ball.
The natives, when a person gets corpulent, tell him that he has grown as
fat as a mamayacu.

The ocean species, from having the skin about the abdomen looser than
that above, floats, when it becomes distended with air, with its back
downwards. It can thus move about as rapidly as in its usual position,
by aid of its pectoral fins. By the movement of its jaws it makes a
curious noise, and can give with its sharp teeth a severe bite. The
skin is also covered with small spikes, which, when thus inflated,
become erect and pointed.

It thus, though at first sight looking as helpless as can be, is well
able to defend itself.

The diodon has been known to be swallowed alive by a shark, in whose
stomach it was found floating, probably supported by the air with which
it had become inflated. It is asserted that it also frequently eats its
way, not only through the coats of the shark's stomach, but through the
sides of the monster, which is thus killed. Probably the little diodon
of the Amazon has a similar means of revenging itself on the voracious
monsters to whom it falls a prey; and though it might not be able to
liberate itself through the scaly back of an alligator, it would
inevitably kill the monster, or cause him such pain as to make him
repent having swallowed so indigestible a morsel.

The magnificent pirarucu or anatto, of vast size, with its ornamental
coat of mail, and broad large scales margined with bright red, peoples
the waters in immense numbers. It is most frequently caught by the
native fishermen; and when salted, forms the staple food of all classes
on the banks of the Lower Amazon. It swims at great speed, and attains
the length of eight feet when full-grown, and five feet in girth. The
Indian name of pirarucu is given to it from the native words _pira_,
fish, and _urucu_, red; in allusion, says Mr Bates, to the red colour
of the borders of its scales.

Among the other fish most frequently caught are the surubim and
piraepieua (species of Pimelodus); very handsome fishes, four feet in
length, with flat spoon-shaped heads, and prettily spotted a