x, c, s Merrill: Botanical Exploration of the Philippines 161 
from the area up to the latter part of the year 1912. Since 
the publication of this work no attempt has been made to con- 
tinue botanical exploration in the vicinity of Manila, yet casual 
collecting and observation in the past two years have added 
to the forms enumerated in the Flora of Manila representatives 
of three families, thirteen genera, and twenty-three species. 
If is absolutely certain that any continued intensive exploration 
of the area would add some scores of species to the list of those 
known from the vicinity of Manila, and yet the Flora of Manila 
was based on the collections accumulated during a period of 
ten years, with more than one year of systematic and intensive 
exploration of the area. What is true of Manila is undoubtedly 
true of the few other parts of the Malayan region that are well 
known botanically. 
In the Philippines those regions that may be considered to 
be fairly, but not exhaustively, botanically explored are small 
in area and few in number. Under this head, in addition to 
the region about the city of Manila extending some miles in- 
land to the east of Antipolo, we may also include a portion of 
the eastern slope of Mount Mariveles in Bataan Province, Lu- 
zon, and just across the bay from Manila; the region about 
the College of Agriculture at Los Banos, Laguna Province, 
Luzon; the region about Baguio, Benguet Subprovince, Luzon; 
and perhaps also the region about Bauco, Bontoc Subprovince, 
Luzon, and Mount Apo, District of Davao, Mindanao. These 
are the only areas in the Philippines where botanical explora- 
tion has been intensive and fairly continuous in all or most 
months of the year. 
A point to be considered, in the botanical exploration of 
densely forested mountains in the Philippines, is that even on 
those mountains which have been visited by many botanists and 
collectors, such as Mounts Mariveles, Santo Tomas (Tonglon), 
Maquiling, Arayat, and Banajao, botanical exploration has been 
confined to very narrow strips from the base to the summit; 
sometimes to a single strip as on Santo Tomas, sometimes to 
several strips as on Mount Banajao. Other mountains, such 
as Mounts Halcon, Pinatubo, Data, Ugo, Pulog, Polis, Mayon, 
Iraga, Isarog, Malindang, Canlaon, Pulgar, Victoria, and Ca- 
poas, are known botanically from collections made by single 
or few collectors on hurried trips. In many cases our knowl- 
edge of the flora of certain mountains is based on material 
collected on single trips, and the area actually explored would 
at most average a few meters in width. The richest flora is 
not found on the lower slopes or the exposed peaks and ridges, 
