354 NOTES OF A BOTANIST 
Other day, from about midway along the Casiquiari, and he pro- 
mises to write me again, should there be opportunity, from 
Esmeralda. 
As to the modes of reaching the sources of the Orinoco, besides 
that of following the river itself, there seem to be several. When 
I was at the Barra, the most direct route seemed to be by the 
Rio Padauiri, whose mouth is a little eastward of the 64th 
meridian. This large river has its sources in the Serra de Tapiira- 
pecu or Ox's-tongue, and the Orinoco is considered to rise on 
the north-eastern slopes of the same serra. Persons who have 
ascended high up the Padauiri, in quest of salsaparilla, assure me 
they have met Indians from the sources of the Orinoco. The 
river Padauiri, however, gives dysentery and the ague to every one 
who enters it, and it was here my countryman Mr. Bradley caught 
the illness which proved fatal to him, while cutting piassaba with 
a party of Indians. The Marania is the next large river entering 
the Rio Negro on the same side, but its course is ascertained to 
be much shorter than that of the Padauiri. The Rio Cauaboris, 
which enters the Rio Negro on the 66th meridian, probably 
extends nearly to the Orinoco. In its lower part it makes a large 
curve to westward, nearly parallel to that of the Rio Negro, and 
I have been assured by Indians at Sao Gabriel that it ran not much 
to the eastward of that place. From Marabitanas, the frontier 
town of Brazil, I could distinctly see, though at a great distance, 
the serrania called Pira-puku or The Long Fish, whose base is 
laved by the Cauabon's. This lofty ridge seems to run westward, 
trending slightly northward, and the portion of it seen from Mara- 
bitanas extends through an angle of about 90° (from E. nearly to 
N.), its prolongation westward being hid from view by the forest 
on the opposite side of the river. With my telescope I could 
distinguish steep escarpments, bare of forest, but in no part could 
I distinguish the trees, the forest-clad portion being only recog- 
nisable from its colour. I suppose that in their highest part — an 
abrupt truncate peak about midway — they may be nearly 4000 
feet above the plain. Those who have ascended the river 
Cauabon's describe it as very picturesque and possessing a peculiar 
vegetation. Certain curious plants, said to resemble both palms 
and ferns, from the description given me can only be Cycades. I 
was delighted to meet with a Cycas in the Uaupes, though it never 
showed signs of flowering ; it is the only species of this tribe I 
have seen in South America. 
The Rio Cauabon's is easily reached from San Carlos by pro- 
ceeding up the Pacimoni, a tributary of the Casiquiari, and up 
its southern branch the Baria, from which there is a short portage 
to the Cauabon's ; but nothing of bulk could be taken this way, 
and I have reason to believe that the Cauabon's does not reach 
the Cerro de Tapii'ra-pecu. 
