374 NOTES OF A BOTANIST CHAP. 



1854, when I was at San Carlos del Rio Negro 

 (lat. r 53^-' S.), I saw them going northward in 

 November and returning southward in May, and 

 had the pleasure of having some of them stay to 

 dine with me. One of their halting-places on their 

 way to the Orinoco was on islands near the mouth 

 of the Casiquiari, at only a few hours' journey above 

 San Carlos. There I have seen them roosting on 

 the tree-tops in such long close lines, that by moon- 

 light the trees seemed clad with white flowers. 

 They descend to sandy spits of islands to fish in 

 the grey of the evening and morning, i.e. before 

 betaking themselves to their eyrie, and before 

 resuming their journey on the following day. The 

 scarcity of fish in rivers of clear or black water is 

 well known ; and even were they more abundant, 

 this very clearness of the water would render it 

 difficult for fish-eating fowls to catch them, unless 

 when there was little light ; hence, perhaps, the 

 Ibis's choice of hours for fishing; and the turbid 

 water poured into the Rio Negro by the Casiquiari 

 dulls its transparency at that point, which makes it 

 eligible for a fishing-station, leaving probably only 

 a single day's stage for the travellers to reach the 

 Orinoco. The Ibises, however, did not, as one 

 might have supposed, turn up the Casiquiari, but 

 held right on to the north, crossing the isthmus of 

 Pimichin, and descending the Atabapo to the 

 Orinoco. Some of them, I was told, would halt 

 on the Guaviare, whose turbid waters, alligators, 

 turtles, etc., quite assimilate it to the Solimoes or 

 Upper Amazon ; and others push on to the Apure ; 

 the former lot, however, are said to travel chiefly 

 by way of the Japura from the Amazon. Those 



