NovEMBER 15, 1910] Tue Ferns or Mount Aro 
tions elsewhere, but did not on Apo, because I had just 
been there. In 1905, Mr. R. S. Williams, of the New York 
Botanical Gardens, made an extensive collection in the district 
of Davao, including a fair proportion at and above Todaya. 
Mr. Elmer collected here from April to October, 1909, using 
Todaya as a base. He spent fifteen days at Baclayan in 
August, and a few days in September, making three trips 
to the summit. Six visits were made at different times to 
the summit of Mt. Calelan. 
For several reasons it seems worth while, in connection 
with the study of this collection, to list all the species known to 
occur at any considerable altitude on the mountain mass of Apo 
-J 
and Calelan. The total number of these is more than two hundred 
and fifty. While exact data for a comparison are wanting, it 
is probable that this is the richest known fern flora in the world. 
Raciborski, in his Pteridophyten der Flora von Buitenzorg, takes 
up three hundred and fifty one species; but this includes 
a very considerable number merely “Aus Java angegeben,’’ or whose 
known places of occurrence are fairly remote. The two hundred 
and fifty two here listed from the mountain do not include some 
dozens which have been collected in the neighboring coastal plain. 
In speaking of the local distribution of these ferns, I 
must refer for general information and for the basis of com- 
parison to my paper on the Comparative Ecology of San Ramon 
Polypodiaceae. The number of species known from the dif- 
ferent étages is as follows:— 
Apo San Ramon 
(Filicineae) (Polypodiaceae) 
Alpine brush: L6... 5 0 
Mommy forest ..... 4 76 10 
-Ban famemb ccs ose 96 59 
High lot -n Pee 62 81 
The species of the coast and Savanna woods are not taken 
into account here. If a fair proportion of attention had been 
-given to the collecting in the high forest region about the 
base of Apo, it is safe to assume that it would have yield- 
ed a larger number of species than we have from the same 
type of environment at San Ramon, though not in the same 
proportion that the rain forest species are more numerous 
on Apo and Calelan. 
