8 AMERICAN FERN JOURNAL 
the banks of streams in this vicinity the very rare 
Dryopteris cumingiana was collected in great abundance. 
The streams of the Juan Diaz-Pacora region fall. 
into two classes as regards the fern flora to be found 
along their banks. The larger rivers, as the Juan Diaz, 
Tapia, Tacumen, Tataria, and Pacora, with a width 
exceeding fifteen feet and a depth of two to five feet 
(at a time of average rainfall), are characterized by 
coarse species of Tectaria and Pteris, and by Dryopteris 
mollis, D. Mercurii, Blechnum occidentale, Asplenium 
obtusifolium, and the densely tufted Asplenium for- 
mosum. Probably the most abundant of the terrestrial 
ferns found in this habitat are Cyclopeltis semicordata 
and the many species of Adiantum. On the limbs of 
trees overhanging these streams are seen the giant 
Polypodium phyllitidis and Asplenium serratum, both 
in outline resembling somewhat our Scolopendrium 
vulgare. 
The steep banks of the smaller streams present quite 
a different fern flora. Two species of Leptochilus occur 
in great quantities, running on the clay soil and climb- 
ing over rocks and up trees. The narrow gorges are 
choked with specimens of the coarse ferns Danaea 
nodosa, Saccoloma elegans, Alsophila blechnoides, and 
Diplazium grandifolium. Climbing over shrubs and 
trees is Lygodium radiatum, a species nearly confined 
to the Isthmus. 
The first trip was made to this region September 30, 
1917, and the last May 12, 1918, so that opportunity 
was afforded for studying the flora during the succession 
of seasons. The amount of rainfall increased rapidly 
from September to November, reaching its maximum 
about the end of November. In December it fell off 
considerably; in January there were only two or three 
showers; in February and the first twenty days of 
March there was practically no rain at all; while in 
