THE RIVER TROMBETAS 
small herb of the Violet tribe, lonidium oppositi- 
folium. Various species of the same genus grow 
in other parts of Brazil, where their roots afford a 
sort of Ipecacuanha, quite equal as an emetic to 
those of the true Ipecacuanha (Cephaelis), but not 
so mild in their operation. I did not, however, 
again fall in with any lonidia until many years 
afterwards, when I came upon them in the Andes 
of Quito at 9000 feet elevation. 
Shady rills, that came down the declivity on the 
right bank of the river, nourished a good many 
ferns on their banks, but no very noticeable species. 
Of palms rising to the height of trees there 
were seven or eight kinds, all of which I had seen 
also on the Amazon ; but there were several palms 
of humbler growth, species of Bactris and Geonoma, 
which I had not noticed before. 
Damp shady hollows, where the vegetable 
mould lay deep, were often overspread with 
Helosis brasiliensis , Mart, (of the natural order 
Balanophoraceae), one of the lowest forms of flower- 
ing plants, looking quite like the young state of 
some fungus (Agaricus or Polyporus), until what 
seems to be an unexpanded cap is found to be a 
solid oval head, of a reddish-brown colour, studded 
with minute flowers of the most rudimentary 
structure. I have seen it at several points in the 
Amazon valley, and it reappears near the coast of 
the Pacific, at the western foot of the Andes. 
The following additional observations on the 
caxoeiras or cataracts of the Aripecurii are all I 
could make during the four rainy days of my stay 
there. 
The first caxoeira is a distinct fall of a few feet 
