r shape, and the
greater length and thickness of their tails." Near the Tapajos we met a
third species, called _Mata-mata_. It has a deeply-keeled carapax,
beautifully bossed, and a hideous triangular head, having curious,
lobed, fleshy appendages, and nostrils prolonged into a tube. It is
supposed to have great virtues as a remedy for rheumatism. But the most
noticeable feature of the Amazonian fauna, as Agassiz has remarked, is
the abundance of cetaceans through its whole extent. From the brackish
estuary of Para to the clear, cool waters at the base of the Andes,
these clumsy refugees from the ocean may be seen gamboling and blowing
as in their native element. Four different kinds of porpoises have been
seen. A black species lives in the Bay of Marajo. In the Middle Amazon
are two distinct porpoises, one flesh-colored;[172] and in the upper
tributaries is the _Inia Boliviensis_, resembling, but specifically
different from the sea-dolphin and the soosoo of the Ganges. "It was
several years (says the Naturalist on the Amazon) before I could induce
a fisherman to harpoon dolphins (_Boutos_) for me as specimens, for no
one ever kills these animals voluntarily; the superstitious people
believe that blindness would result from the use of the oil in lamps."
The herbivorous manati (already mentioned, Chap. XV.) is found
throughout the great river. It differs slightly from the Atlantic
species. It rarely measures over twelve feet in length. It is taken by
the harpoon or nets of chambiri twine. Both Herndon and Gibbon mention
seals as occurring in the Peruvian tributaries; but we saw none, neither
did Bates, Agassiz, or Edwards. They probably meant the manati.

[Footnote 172: _Dephinus pallidus_. Bates observed this species at Villa
Nova; we saw it at Coary, 500 miles west; and Herndon found it in the
Huallaga.]

CHAPTER XXI.

Life around the Great River.--Insects.--Reptiles.--Birds.--Mammals.

The forest of the Amazon is less full of life than the river. Beasts,
birds, and reptiles are exceedingly scarce; still there is, in fact, a
great variety, but they are widely scattered and very shy. In the
animal, as in the vegetable kingdom, diversity is the law; there is a
great paucity of individuals compared with the species.[173] Insects are
rare in the dense forest; they are almost confined to the more open
country along the banks of the rivers. Ants are perhaps the most
numerous. There is one species over an inc