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651 
box gorges, where seepage is constant during the dry season and where 
the insolation is low, delicate shade or mesophytie plants, usually ferns, 
are found. Here the tree fern, Alsophila contaminans is present and 
the very delicate Lindsaya concinna forms thick growths with Mvtcro- 
lepa pinnata, Nephrodium cuspidatum,; Schizmatoglottis, Geophila, 
and Gymnopteris, already mentioned as occurring in similar ecological 
situations, are also present. ‘Two liverworts, Anthoceros grandis and 
~one undetermined species of this group, are the only ones noted here. 
The temporarily less mesophytic conditions, due to steepness of the 
slopes or to exposure, or to both, and the temporary climax mesophytic 
vegetation due to unstableness of topography, dampness of soil, and 
low saturation deficit cited above are sufficient to show differences due 
to topographic situation. 
The formation is almost devoid of level stretches which at the same 
time are not exposed. However, gentle slopes are present and where they 
are not near to the edge*of ridges, they exhibit vegetative appearances 
as nearly akin to the stable climax condition as the climate is able to 
support. Such slopes are encountered in the small cirque-like basins 
situated at the heads of small streams, or still better on the south side 
of the Lamao, near the head waters of the Camayauan and Alangan 
rivers. It is here that the Dipterocarpacee, especially Shorea poly- 
sperma, S. contorta, and Hopea acuminata, reach their best development. 
Prominent, and reaching its largest dimensions (200 centimeters in 
diameter), is Agathis philippinensis, and, here also, the best growth of 
Plectronia viridis, Podocarpus blumet, and other associates of the second- 
story vegetation is encountered. 
The epiphytic vegetation, corresponding with the more favorable 
climatic conditions, is more abundant in contrast with the formations 
lower down. ‘The most conspicuous of the epiphytes is the bird’s-nest 
fern, Asplenium nidus. (See Pl. XXXIII.) This is present in pro- 
tected places, such as parts of the forest well back from the ridges, and 
on trees and rocks in the canyons of the Lamao River and its tributaries. 
The rubiaceous ant plant, I/yrmecodia echinata, is also present on the 
limbs of the tall trees. Several undetermined orchids and the ferns 
Davallia solida, Vittaria lineata, Anthrophyum reticulatum, and Poly- 
podium meyenianum are encountered, these species being more abundant 
in the gorges near the stream than they are on the ridges, but nearly all 
of these, as will be shown below, reach their best development at higher 
altitudes. 
Summary.—1. In contrast with the lower formations, that of the 
Shorea-Plectronia shows a climate conducive to a more mesophytic 
vegetation. (See climatic data for Station 3, which is in this formation.) 
2. Corresponding to these conditions the vegetation, as a whole, shows 
a less tropophytic character than that in the lower formations. 
3. However, physiographic situations show a marked variety in the 
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