fluence with the Vaupés and the Colombian border. Since 
this species is endemic to caatingas, however, its dispersal 
is necessarily interrupted and usually confined to the 
hinterlands. Therefore, further explorations may and 
doubtlessly will increase our knowledge of its range. 
Inasmuch as the Fr6es collections from Jauareté were 
made exactly on the Colombo- Brazilian boundary, it is 
safe to include Hevea rigidifolia in the enumeration of 
Colombian species of the genus (Schultes in Bot. Mus. 
Leafl. Harvard Univ. 12 (1945) 11). In 1945, I published 
the following remarks in this connection (here translated 
from the Spanish) (in Rev. Acad. Col. Ciéne. Exact. Fis- 
ico. Nat. 6: nos. 22-23 (1945) 386): ‘*This species, col- 
lected by the English botanist, Richard Spruce, in caatin- 
gas in the lower Vaupés near Panuré, Brazil, is repre- 
sented in herbaria only by the type collection. The type 
locality at Panuré is very near the boundary between 
Colombia and Brazil and, for this reason, it seems prob- 
able that Hevea rigidifolia will also be found in the 
Vaupés of Colombia below Mitt.’ It should be sought 
in the Rio Querari as well. 
For the same reason, I suspect that in time we shall 
also be able to assign Hevea rigidifolia to the Venezuelan 
flora. [t should be expected to occur in the general vicin- 
ity of the Piedra de Cocuy. Pittier (Manual de las plan- 
tas usuales de Venezuela (1926) 262) indicates that Hevea 
rigidifolia forms a part of the Venezuelan flora, but I 
strongly suspect that this statement is based upon col- 
lections of the very thick-coriaceous Hevea pauciflora 
(Spruce ex Bentham) Muell.-Arg. var. coriacea Ducke, 
“In the small but critically interesting collection of Hevea which 
Paul H. Allen, of the Missouri Botanical Garden, made in this gen- 
eral area in 1943 and 1944 for the Rubber Development Corporation, 
H., rigidifolia is not represented. (See Baldwin in Amer. Journ. Bot. 
34 (1947) 268 for reference to Allen 3049.) 
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