374 NOTES OF A BOTANIST 
1854, when I was at San Carlos del Rio Negro 
(lat. 1° ^2>¥ ^ 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 Apur6 ; 
the former lot, however, are said to travel chiefly 
by way of the Japura from the Amazon. Those 
