not to be a Castilloa at all, but a Perehea. I searched everywhere 
for this species without ever coming across it, nor had any of the 
various experienced native collectors I questioned ever heard of 
any other but the Caucho tree (C. Elastica) 
KOSCHAY, in a letter which last year appeared in the March issue 
of the u Tropenpflanzer'” describes four different Castilloa as oc- 
curring in Costa Rica. Of these C. twin, has already been men- 
tioned". Of the rubber yielding Castilloa, the best is the one 
possessing a whitish bark ; it yields plenty of excellent rubber. 
Another variety has a black bark with a rough and irregular 
surface, it yields a rubber as good as the white variety, but the 
tree is rapidly exhausted. A further variety is characterised by a 
reddish bark, very thin and fragile ; it yields very little latex, but 
the rubber produced is of good quality. 
To this must be added that the Castilloa of Panama appears to 
differ from all other known varieties by the occasionally quite 
enormous size of the leaves. Leaves 20 inches in length occur very 
commonly, especially upon young trees. For this reason it has 
been suggested that the Castilloa of Panama is a, separate species. 
Now, as regards the trees at Las Cascadas, while at first sight 
they certainly strike one as typical Castilloa elastica, on closer ex- 
amination show a number of differences which, at any rate in the 
absence of flowers, render the identification of the species none too 
easy. In the first instance, the bark of the$,e trees, although very 
smooth, is certainly neither yellow nor white, but a delicate pale 
pinkish brown. The leaves even on the older trees are not very 
great, but still distinctly larger than the leaves on grown up trees 
of C Elastica in Guatemala, Honduras, Nicaragua ancl Mexico. 
The hairv covering on the fovver side of the leaves is much less 
striking, but the young leaf shoots at the end of the branches ap- 
pear quite as densely haired as those of any typical Castilloa. Also 
the phenomenon above referred to as so characteristic of Castilloa 
is very strikingly displayed by all the Castilloa trees at Las 
Cascadas. 
Ofi the other hand, the only valueless species of Castilloa, C. tunu 
is absolutely unknown on the isthmus, and in my wandering I have 
never encountered it. It is equally certain that the Las Cascadas 
Castilloa is entirely different from KOSCHAY’S black and red varie- 
ties ; the appearance of its bark could not possibly be described in 
in the terms used by KOSCHAY for the latter two trees. In how far 
Koschay's white Castilloa corresponds to the Las Cascadas tree is 
difficult to say, The bark of the latter might, with some appearance 
of justification, be described in KosChAy’s term as whitish, but con- 
sidering that the large silvery patches on it do not appear to be the 
actual colour of the bark, but seem to be due to a lichen, and con- 
sidering further that all the lichen-free portions of the bark are by 
no means whitish, but as I stated before, of a light pinkish brown 
colour, I prefer to adhere to this latter description. 
Taking all these points in conjunction it will readily be seen that 
the Las Cascadas rubber trees exhibit all the characteristics of 
Castilloa elastica in regard to the general appearance of the tree, 
