Although Koenig gave no reason for the change, the ex- 
tra vowel was in all probability introduced in order to 
make the name grammatically correct, and was not the 
result, as Pittier states, of a typographical error, ‘‘a slip 
of the pen or the officious but ignorant interference of 
the translator. ’’ 
Whatever the reason for the change, the name Cas- 
tilloa became firmly established in literature, and its use 
was continued unquestioned for nearly a hundred years. 
In 1908, however, O. F. Cook’ (in his memoir on the 
Central American Rubber Tree) pointed out that the use 
of Castilloa for the genus could be ‘‘justified by no rec- 
ognized rule of botanical nomenclature.*’ Pittier’, who 
monographed the genus in 1910, concurred in this opin- 
ion. Certainly there have been no recent changes in the 
laws of priority or other rules of nomenclature that would 
make the use of Castilloa any more permissible at the 
present time. 
In America at least, Castilla is quite generally con- 
sidered to be the name which must be taken up for this 
genus, even though Castilloa may be grammatically cor- 
rect. As evidence of this, recent publications of such 
authorities as Bailey', Britton and Wilson’, Record and 
Mell’, and Standley'’"’*" may be cited. here is evi- 
dence also that taxonomists in other parts of the world 
are reverting to the older name. Burkill’, for example, 
uses Castilla and comments briefly on the ‘‘mischance’’ 
which was responsible for the adoption of Castilloa. 
Although over thirty years have elapsed since Cook 
pointed out that Castil/a was the correct name for the 
rubber trees of Central America and Mexico, it is not at 
all surprising that most of the literature on economic 
botany continues to use the more familiar Casti/loa. It 
is strange, however, that the competent taxonomists in 
England and on the continent continue to condone the 
[ 162 
