VOYAGE UP THE COAST TO PARA'. 143 



creek, having first fastened the seine across from shore 

 to shore at a lower point, and when they have gained 

 a certain distance above it, they spring into the water 

 with a great plash and rush down the creek in a line, 

 driving the fish before them into the net. One draught 



o o 



alone filled the boat half full of fish. Mr. Agassiz was 

 especially interested in seeing alive for the first time the 

 curious fish called " Tralhote" by the Indians, and known 

 to naturalists as the Anableps tetrophthalmus. This name, 

 signifying " four-eyed," is derived from the singular struc- 

 ture of the eye. A membranous fold enclosing the bulb of 

 the eye stretches across the pupil, dividing the visual 

 apparatus into an upper and lower half. No doubt this 

 formation is intended to suit the peculiar habits of the 

 Anableps. These fishes gather in shoals on the surface 

 of the water, their heads resting partly above, partly below 

 the surface, and they move by a leaping motion somewhat 

 like that of frogs on land. Thus, half in air, half in water, 

 they require eyes adapted for seeing in both elements, and 

 the arrangement described above just meets this want. 



August ~L9th. To-night at ten o'clock we go on board 

 the steamer, and before dawn shall be on our way up 

 the river. This has been a delicious week of rest and 

 refreshment to me. The quiet country life, with morning 

 walks in the fresh, fragrant lanes and roads immediately 

 about us, has been very soothing after four months of 

 travel or of noisy hotel life. The other day as we were 

 going into town we found in the wet grass by the road- 

 side one of the most beautiful mushrooms I have ever 

 seen. The stem was pure white, three or four inches in 

 height, and about half an inch in diameter, surmounted by 

 a club-shaped head, brown in color, with a blunt point, 



