single concentration of this species I found at Sao Felipe. 
Immediately in back of this tiny town there are several 
meandering brooks which, in the rainy season, become 
creeks. The land about three quarters of a mile behind 
the town rises gently, and one finds Hevea guianensis 
var. lutea and H. pauciflora. Brooks rise on these ele- 
vations, but when they reach the low flat land lying 
immediately behind the town and stretching above and 
below along the river, they broaden and meander and, 
in the wet season, are lost in the general inundation 
which lasts from four to six months. It is in this low- 
lying land that one finds Hevea microphylla. In the 
vicinity of Sio Felipe, in the areas where it is found, it 
occurs to the exclusion of Hevea Benthamiana, and in 
densities which I estimated, along the creeks, at an aver- 
age of about 7 to 10 per hektar. From Sao Felipe up to 
the mouth of the Rio Icana, AZevea microphylla is found 
in high concentration. Hevea Benthamiana grows near 
Sio Felipe, but on slightly higher banks which, unlike 
the meandering creek beds, protrude appreciably (up to 
twelve feet or more) during the dry season and become 
quite firm and dry. The land on which /Zevea micro- 
phylla oceurs at Sio Felipe, as elsewhere, is almost al- 
ways boggy even though it is rather sandy. That AZevea 
microphylla sometimes occurs in estradas with A. Ben- 
thamiana is not ecologically significant, for an estrada is 
a twisting and direction-less, so to speak, path made by 
a tapper to reach his trees. Hevea microphylla is never 
tapped, but a tapper may pass any number of trees of 
this species to reach stands of HT. Benthamiana. The 
estrada, in other words, may cut across the lower lying 
areas inhabited by HZ. microphylla. 
In my field book, I wrote the following passing ob- 
servations while going up the Rio I¢ana in April 1948: 
‘Inthe Ieana, Hevea microphylla is by far the common- 
[ 1384 ] 
