[6 Ridley.—The Distribution of Plants. 
species. The epiphytic species have a smaller distribution than the terres¬ 
trial species, as the epiphytic area in the world is smaller than the non- 
epiphytic area. Of Lycopodium , three species, all terrestrial, occur in Asia, 
Africa, and America, and one, Z. complanatum, over the palaearctic zone and 
into the tropic mountain regions, but our variety thujoides looks very 
different from palaearctic complanatum and may be specifically distinct. 
The remaining species range over India or Africa to Polynesia, except 
three confined to the Malay Isles. 
Psilotunu Two species very readily propagated by bulbils as well 
as spores, growing on trees, rocks, and ruins freely, have a wide distribu¬ 
tion all over the tropics and to Japan and New Zealand. 
It will be noticed there is a very marked difference between the 
distribution of Selaginellaceae and Lycopodiaceae. According to the age 
and area hypothesis this would show that the Selaginellaceae were a very 
modern group and the Lycopodiaceae an ancient group, for which there 
is no further evidence. 
The real cause, I think, is this : the Selaginellas are low-growing, often 
creeping, plants, producing comparatively few spores, and, growing in dense 
forests, have a comparatively slow dispersal, while the Lycopodiaceae are 
either high-borne epiphytes on the top of lofty trees or grow in dry open 
places, and produce great abundance of spores which are readily dispersed 
by wind. It is interesting to note that one of the earliest plants to 
reappear on Krakatau after the destruction of its flora was Lycopodhim 
cernuum , of world-wide distribution, showing how rapidly this plant is 
dispersed by its light and abundant spores and its open-country habitat. 
Ferns. 
In the Malay Peninsula we have about four hundred species, A certain 
number, but not very many, are endemic, most extend over the Asiatic 
tropics, and many to Madagascar and Africa. Only about twenty also 
occur in America, and one or two of these may be escapes from cultiva¬ 
tion. Only three species occur also in Europe, viz. Pteris aquilina , Linn., 
Trichomanes radicans , Sw., and Lastraea thelypteris , Desv. 
Pteris aquilina , Linn., occurs nearly all over the world in temperate and 
tropical regions. It is quite absent from oceanic islands, and its earliest 
record is from late glacial or Neolithic deposits in Sweden (Gunnar Ander¬ 
son, in Clement Reid, c Origin of British Flora*, p. 168). I have some evi¬ 
dence that it is occasionally, at least, transported by man, the spores attach¬ 
ing themselves to cloth, gunny-bags, &c. It is abundant in sandy soil in the 
Malay Peninsula, but was quite absent from the plateau of Gunong Tahan 
when the locality, hitherto unvisited by man, was explored by Mr. Robin¬ 
son in 1906. In 1910 I visited the mountain, and beneath the floor of 
Robinson’s old hut, and beneath one occupied by a surveyor a year or two 
