THE GYMNOTUS. 599 



of the water, they require eyes adapted for seeing in both ele- 

 ments, and the arrangement described just meets this want. 



THE PARROT-FISH. 



The birds of the air have, in this region, their representa- 

 tives in the water. Among them is the curious and handsome 

 pirarara, or parrot-fish. It is a heavy, broad-headed creature, 

 with a bony shield over the whole head. Its general colour 

 is jet-black, its bright yellow sides deepening into orange here 

 and there. The yellow fat of this fish has a curious property. 

 The Indians assert that when parrots are fed upon it they 

 become tinged with yellow, and they often use it to render 

 their papagaios more variegated. 



THE GYMNOTUS. 



On the Amazonian waters is found the carapus, called 

 by the Brazilians sarapo, belonging to the genus Gymnotus ; 

 though far smaller than the electric gymnotus. They are very 

 numerous, and the most lively of the whole group. Their 

 motions are winding and rapid, like those of the eel ; but yet 

 different, inasmuch as they do not glide quickly forward, but 

 turn frequent somersaults, and constantly change their direc- 

 tion. 



LOCALIZATION OF FISH. 



The researches of Professor Agassiz prove that the localiza- 

 tion of species of fish in these waters is peculiarly distinct 

 and permanent, their migrations being very limited consist- 

 ing chiefly in removing from shallow to deeper waters, and 

 from these to shallow again, at those seasons when the range of 

 the shore in the same water-basin is affected by the rise and fall 



