320 A DAY AND NIGHT ON THE AMAZON, 



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 recog- 

 nized them for what they really are — fresh-water shells of the 

 family of the Naiades. As their resemblance is very remark- 

 able, 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 im- 

 mense 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 gTinding 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 east- 

 ward 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 theii- 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 



