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very evidently the better. The fern flora of Mindanao as a whole 
naturally shows a stronger predominance of Celebes affinities. The most 
conspicuous example is Acrosorus , with one species on Mount Apo, one 
in Celebes, and a third in Samoa. 
II. LOCAL GEOGRAPHY. 
San Eamon is situated on the Sea of Jolo, 14 miles from Zamboanga. 
The coastal plain here is at most 5 kilometers broad, and at least 50 
meters in altitude at the back, from which small mountains rise abruptly. 
The back part of this plain, and the mountains, are clothed with virgin 
forest, while land near the shore is for the most part in cultivation. 
The streams, the largest of which is the Sax Eiver, are superficial on 
the plain to which they add more than they erode. Along the Sax a 
flood-plain a few meters wide has been developed less than 2 kilometers 
into the mountains. Above this, the river descends through a canon, in 
most places quite without any level floor, the walls of which are in but few 
places too steep to be wooded. At the head of this canon, at an altitude of 
200 meters, the river forks, its two parallel branches entering through 
practically impassable gorges. The ridge between these is 600 meters 
high at its abrupt lower end. This, and the neighboring ridges and the 
mountains nearer the coast, are remains of a plateau, which, 6 kilometers 
farther inland, at an altitude of about 800 meters, is still well preserved, 
the creeks being hardly 50 meters below its level. Prom the hack of this 
plateau, altitude 900 meters, Mount Balabac rises abruptly to 1,200 
meters. The summit it fiat, but small. 
As I find it convenient to classify the vegetation, we have here : 
The strand; including all places where the plants are subject to the deposition 
at any time of salt from the atmosphere. . 
The salt marsh; only a few spots, the only fern in which is Achrostichum 
aureum. 
The savanna-ioood, including: 
(а) The low jungle; low places near the coast, wet throughout the dry season. 
( б ) The parang; drier lowlands, without large trees, whether as a result of 
the dryness of the soil or because the trees have been removed. 
The high forest (in Brandis’ sense) ; a forest containing large trees, in which 
there is a pronounced dry season; this includes part of the coastal plain and the 
lower mountains and ridges. 
The rain forest ; a forest in which the dry season is broken by showers and 
practically no plants are deciduous; this includes the high plateau and the slopes 
of Mount Balabac. 
The mossy forest; stunted woods with an exuberance of epiphytes; this is 
rather feebly developed on the main summit. 
Like other classifications, this one is artificial; the several divisions 
blend, they are not absolutely coordinate, and they are not units, but it 
is convenient, applicable to the field, and more approximately correlated 
with the ferns’ physiology than is any other classification that preserves 
any semblance of geographical cohesion. From the standpoint of the 
