8 
Polypodiacece from various parts of the island, which are not known, about 
San Eamon. If these be considered each by itself, there is not one which 
can be regarded as a probable immigrant from the north. 
To return to the wav„e figure, we see. that no wave from north of Luzon 
has brought any ferns to Mindanao. Of the many waves from Malaya, 
some have reached only to Mindanao, a few to the Visayan Islands, the 
greatest force of them to Luzon, and a few still farther. It is not 
irrelevant to point out here that the Malayan element is little short of 
absolute, even in Luzon. One hundred and twenty-two, or 80 per cent, 
of the San Eamon ferns with the outside distribution of which I am at 
all acquainted, occur in Luzon. Beside sharing such a proportion as 
this of the ferns of the southern Philippines, Luzon has many charac- 
teristic Malayan species still unknown elsewhere in the Philippines. 
Beside these, it has a few Himalayan species. Since the accepted distri- 
bution of some species such as Nephrodium flciccidum, Meniscium cuspi- 
datum, etc., not yet found in China, is from the Himalayas through 
Malaya to Luzon, and many species have this range and China, in addi- 
tion, it is not unlikely that plants now known only from the Himalayas 
and Luzon, or even from these and China, have at some time been 
continuously distributed through Malaya. Therefore, the existence of 
these species is not in itself strong evidence of a direct migration between 
Luzon and continental Asia. 
There are a few ferns known only from Luzon and the regions north 
of it: Polystichum varium Pr., P. deltodon Diels, Nephrodium erythroso- 
rum Hook., Athyrium anisopteron Christ, and Plagiogyria stenoptera 
Diels. Of these, Polystichum varium is as likely to have originated in 
one part of its range as in another. The Nephrodium is as likely to have 
migrated northward, because the greatest development of its genus and 
section ( Lastraea ), is Malayan. Plagiogyria is most probably a north- 
ward migrant from Luzon because the Philippines have about as many 
species in the genus as all the rest of the world. Finally, Woodwardia 
radicans has been regarded as a northern element of this flora but our 
plant is intermediate between the Japanese and Formosan form (IF. 
orientalis Swtz.) and the widespread typical form found in Java; there- 
fore, it is strongly probable that the Japanese plant was derived from 
Luzon. The boreal element in the fern-flora even of Luzon is, then, 
exceedingly insignificant. 5 
I have spoken of the Mindanao fern flora as immigrant from Malaya. 
The greater part of my evidence proves only a close affinity, but not the 
direction of migration. That this has been northward for the ferns as 
a whole is indicated by the high proportion of endemic species (showing 
the Philippines to be not truly continental islands, while floras are 
6 This is by no means so true for the whole of the flora of Luzon. Some 
families better represented to the north, such as Oompositae, show relatively 
large numbers of immigrants here. 
