f every
zoological class--infusoria, hydras, fresh-water shells (chiefly
Ampullaria, Melania, and Unios), aquatic beetles (belonging mostly to
new genera), fishes, reptiles, water birds, and cetaceans. The abundance
and variety of fishes are extraordinary; so also are the species. This
great river is a peculiar ichthyic province, and each part has its
characteristics. According to Agassiz, the whole river, as well as its
tributaries, is broken up into numerous distinct fauna.[170] The
_pirarucu_, or "redfish" (the _Sudis gigas_ of science), is at once the
largest, most common, and most useful fish. The Peruvian Indians call it
_payshi_. It is a powerful fish, often measuring eight feet in length
and five in girth, clad in an ornamental coat-of-mail, its large scales
being margined with bright red. It ranges from Peru to Para. It is
usually taken by the arrow or spear. Salted and dried, the meat will
keep for a year, and forms, with farina, the staple food on the Amazon.
The hard, rough tongue is used as a grater. Other fishes most frequently
seen are the prettily-spotted catfish, Pescada, Piranha, Acara, which
carries its young in its mouth, and a long, slender needle-fish. There
are ganoids in the river, but no sturgeons proper. Pickerel, perch, and
trout are also wanting. The sting-ray represents the shark family. As a
whole, the fishes of the Amazon have a marine character peculiarly their
own.

[Footnote 170: We await the Professor's examination of his "more than
80,000 specimens" before we give the number of new species.]

The reptilian inhabitants of this inland sea are introduced by numerous
batrachians, water-snakes (_Heliops_), and anacondas. But alligators
bear the palm for ugliness, size, and strength. In summer the main river
swarms with them; in the wet season they retreat to the interior lakes
and flooded forests. It was for this reason that we did not see an
alligator on the Napo. At low water they are found above the entrance of
the Curaray. About Obidos, where many of the pools dry up in the fine
months, the alligator buries itself in the mud, and sleeps till the
rainy season returns. "It is scarcely exaggerating to say (writes Bates)
that the waters of the Solimoens are as well stocked with large
alligators in the dry season as a ditch in England is in summer with
tadpoles." There are three or four species in the Amazon. The largest,
the Jacare-uassu of the natives, attains a length of twenty feet. Th