IX, ©, 3 Robinson: Distribution of Philippine Mosses 208 
mate analysis, of course, many species must be considered to 
have been introduced. 
One consideration that should always be kept at least sub- 
consciously present in discussing the relationships of floras, is 
that a species has not necessarily had its origin in nature at the 
place or even in the country from which it was first described, 
not even if that place or country has supplied its specific name. 
Yet it is difficult to avoid a mental bias in this direction, above 
all when a species has been known for a long period of time 
only from the general region where it was first discovered, 
especially as it is practically always very difficult and usually 
impossible to get definite evidence as to its actual place of origin. 
In the case of species of mosses of wide distribution, this can 
only be a matter of inference. 
This inevitably colors the whole of the present discussion, for 
the ascertained moss flora of the Philippines has multiplied five- 
fold in the last ten years, and among these added species are 
very many that have been known for long periods of time from 
other regions. They are thus spoken of as Malayan, or as 
whatever else they appear to be, and there is the less general 
objection to this, in that the Philippines are known to be of 
comparatively recent geologic origin. Yet there have originated 
here, so far as present knowledge permits statement, no less than 
five endemic genera of mosses and numerous endemic species. 
It is by no means impossible, therefore, that here also may be 
the original home of many other species, that have been first 
collected in or described from other groups of islands, and will 
herein be discussed as if they more properly belonged to the 
latter. 
Nothing is more conspicuous to even the most careless ob- 
server, who climbs any of the higher mountains of the Philip- 
pines, than to find that at a certain elevation, differing on different 
mountains, the trees become more or less dwarfed, and are 
clothed with mosses and hepatics. This is so distinctive that 
this class of vegetation has received the name of “mossy forest.” 
The lower limit of this formation depends roughly on the humid- 
ity, and is higher as a rule on the higher mountains. A very 
large proportion of our mosses occur within this zone; the range 
of others extends to sea level. They are epiphytic or terrestrial, 
in somewhat strong contrast to the hepatics and lichens, very 
few are epiphyllous, and these not truly so, extending over the 
surface of leaves because they happen to find them along their 
line of growth. 
As a preliminary to detailed discussion, it is desirable to 
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