Amazonian planada. The genus is typical of higher ele- 
vations. It could be referred to as an element of the 
‘‘upland”’ flora of the Amazonian region, but that ex- 
pression might connote the eastern slopes of the Andes, 
where the genus apparently is not represented. Since 
Cunuria prefers the higher areas in the Amazonian re- 
gion, it may be interpreted as a very old genus that has 
spread from the ancient Venezuela-Guiana land-mass. 
Both Schultes (in Caldasia 8, no. 12 (1944) 124-1380; in 
Chron. Bot. 9, no. 2/8 (1945) 123-127) and Baldwin (in 
Journ. Heredity and in Am. Journ. Bot., /oc. cit.) 
have suggested that the hills rising sharply out of the 
Amazonian plain in the Rio Negro—Rio Uaupés’ area of 
Brazil and Colombia possibly represent a route, now dis- 
continuous, along which plants migrated southwestward 
from the Venezuela-Guiana region. There may also have 
been another route southward from the Guianas. Bald- 
win (doc. cit. and in Am. Journ. Bot. 88 (1946) 215-216) 
has considered the Uaupés area to be the center of vari- 
ability of both Hevea and Cunuria. 
Representatives of Cunuria are known from the an- 
cient mountains in southern British Guiana and Surinam. 
The genus is also represented in southern Venezuela 
along the Casiquiare. It is common along the upper Rio 
Negro in Brazil and along the lower Rio Uaupés in Bra- 
zil and Colombia as well as in the area around Sio Paulo 
de Olivenea (one of the highest localities along the Rio 
Solim6es) and in the vicinity of Mandos (a relatively high 
area near the confluence of the Rio Negro with the So- 
lim6des, with a vegetation rather like that of the region 
of Serra de Sapucud, mentioned below). Cunwria is ex- 
ceedingly abundant on the slopes of Cerro de La Pedre- 
® The Rio Uaupés, flowing through Colombian as well as Brazilian 
territory, is known as the Rio Vaupés in Colombia. 
[ 829 ] 
