specimen under Hevea membranacea, but included it un- 
der H. pauciflora, reterring to H. membranacea as ‘‘bene 
distineta.’’ He does not distinguish Hevea membranacea 
from H. pauciflora directly, but from groups of other 
species, and he fails to refer back to his 1866 publication 
of the epithet membranacea. 
It appears that Huber (in Bol. Mus. Para. 2 (1897) 
252) accepted Hevea membranacea as a good species, for 
he enumerated it amongst species which ‘‘ probably” 
were used in the production of rubber. In 1906, how- 
ever, Huber (in Bol. Mus. Para. 4 (1906) 620) apparently 
made no mention of Hevea membranacea in his synopsis 
of the genus. Ule (in Engler Bot. Jahrb. 50, Beibl. 114 
(1918) 17) likewise listed Hevea membranacea as one of 
the species of the northern part of the Amazon. In 1910, 
Pax (in Engler Pflanzenr. [V, 147 (1910) 126) kept up 
Hevea membranacea as distinet from H. pauciflora, sep- 
arating it from Hf. pauciflora in his key (I. ce. 120) on 
only one character — the membranaceous consistency of 
the leaflets, but carefully pointing out (1. c. 118) through 
what limited material this concept was known. 
In 1929, Ducke (in Rev. Bot. Appl. 9 (1929) 629; in 
Arch. Jard. Bot. Rio Janeiro 5 (1980) 156) listed Hevea 
membranacea as occurring in British Guiana and the 
northwestern part of the Estado do Amazonas in Brazil. 
Shortly thereafter, he employed this binomial (in Arch. 
Jard. Bot. Rio Janeiro 6 (1938) 56) to designate trees 
growing on granitic soil at SAo Paulo de Olivenea on the 
Rio Solimoées and along the Rio Uaupés. He also de- 
scribed (1. c. 57) the variety /etogyne, differing primarily 
in a minor character of the pistillate flower. In 1935, 
Ducke (in Arch. Inst. Biol. Veg. Rio Janeiro 2 (1935) 
239) reduced this variety toa form. In 1946, he reduced 
Hevea membranacea to synonymy under FZ. pauciflora 
(in Bol. Téen. Inst. Agron. Norte no. 10 (1946) 24) and 
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