over a region several
thousands of miles in length, and from five to seven hundred miles in
width. It is evident, he considers, that this basin was a fresh-water
basin, these deposits fresh-water deposits. It is true that calcareous
layers thickly studded with shells have been found interspersed with the
clay; but though supposed to be marine fossils, he recognised them for
what they really are--fresh-water shells of the family of the Naiades.
As their resemblance is very remarkable, the mistake as to their true
zoological character is natural: indeed, many travellers have confounded
some fresh-water fishes from the Upper Amazon of the genus of
Pterophyllum with the marine genus Platax. He considers that the
immense glacier which probably existed at the same time that ice,
thousands of feet thick, covered the centre of Europe, must have been
formed in this valley, and then, ploughing its bottom over and over
again, and grinding all the materials beneath it into a fine powder,
must ultimately have forced its way through the colossal sea-wall which
it had built up eastward into the Atlantic.

A DAY AND NIGHT ON THE AMAZON, WITH THEIR SIGHTS AND SOUNDS.

Day is beginning to dawn, the birds are astir, the cicada have begun
their music; flocks of parrots and macaws, and other winged inhabitants
of the forest, pass by in numbers, seeking their morning repast;
beautiful long-tailed and gilded moths like butterflies fly over the
tree-tops. Rapid is the change from the dark night. The sky in the
east assumes suddenly the loveliest azure colour, across which streaks
of thin white clouds are painted. The varied forms of the numberless
trees, imperceptible during the gloom of night, now appear, the smaller
foliage contrasting with the large glossy leaves of the taller trees, or
the feathery, fan-shaped fronds of palms. For a time the fresh breeze
blows, but flags under the increasing power of the sun, and finally dies
away, the heat and electric tension of the atmosphere becoming almost
insupportable.

The heat increases as the day draws on. Languor and uneasiness seize on
every one;--even the denizens of the forest betray it by their motions.
By this time every voice of bird or mammal is hushed. Only in the trees
is heard at intervals the whir of the cicada. The leaves, so soft and
fresh in the early morn, now become lax and drooping. The flowers shut
their petals. The natives, returning to their huts, fall asleep in