rence in areas like Iquitos, where man has greatly dis- 
turbed the natural habitat. Nevertheless, the role of 
hybridization in altering the trees which have been called 
Hevea humilior may have been exaggerated. Further- 
more, these trees do not depart from Hevea pauciflora 
var. coriacea, in its broad sense, to such an extent as has 
been suggested. 
Hevea pauciflora var. coriacea, as | understand it, em- 
braces the material from the Guianas (77. confusa), from 
the widely spread localities of the great Rio Negro val- 
ley, from the Solimoes and Japura, from Iquitos (7. 
humor), and probably also from the Marmellos (#7. 
camporum); it is certainly one of the most variable con- 
cepts of the genus, but I think that it is a concept en- 
joying a fundamental biological homogeneousness. ‘The 
material of Hevea humilior from Iquitos, like that which 
I have collected near Leticia (Colombia) and which sev- 
eral workers have gathered at Sao Paulo de Olivencga, is, 
indeed, different from the more northern representatives, 
but [am in agreement with Ducke that it can be referred, 
without any reservation, to H. pauciflora var. coriacea. 
Later, we may possibly find that Hevea humilior as well 
as HT. camporum should be accommodated within AH. 
pauciflora var. coriacea in the rank of forma, through 
the use of a trinomial, but such a step must await further 
morphological studies for final settlement. Since these 
present notes are not primarily taxonomic, but are meant 
to be chiefly nomenclatural, [ do not propose to discuss 
the minor variations and differences at this time, nor do 
I intend to consider here the suggestions which Baldwin 
and Seibert have made concerning the genetic makeup 
of the concept. These topics will be deferred for consider- 
ation in a general biological study of the taxonomy, 
morphology, and phytogeography of the Hevea pauci- 
flora complex. 
