365 
as well as physiographically the Coco Group forms an integral part of the 
Andamans. Further, it shows that of the possibly predominating elements 
in their flora, the Indo-Chinese element, as a whole, is slightly weaker 
even in that part of the Andamans nearest to Burma than is an element 
indicating a Tenasserim influence and an element indicating a Malayan 
influence. This seems strange when we recollect that not only do the 
Cocos form that part of the Andamans nearest to Burma but that there is a 
shallow ridge, at times raised into islands, along the line between the 
Cocos and the nearest point on the Burmese mainland, whereas Tenas¬ 
serim is at the opposite side of a deep sea, while Malaya is separated from 
the opposite extremity of the Andaman group by a much greater distance 
and by much deeper straits than Burma is from the area under discussion. 
In order, if possible, to account for this peculiarity of distribution, it 
becomes necessary to discuss the probable origin of the flora of the group. 
The first step in such an inquiry is to ascertain the species in a flora 
that may possibly have been introduced and that do not therefore 
necessarily postulate for an isolated locality such as the Cocos any former 
connection with neighboui’ing land. It is, of coui’se, evident that if a 
previous land connection be shewn to be necessary to explain the pre¬ 
sence of any species in the islands this same land connection would 
sufldciently explain the presence of most of the species that occur there 
without requiring the suggestion of any extraneous means of introduc¬ 
tion. But until all the possibilities of introduction by means of physical 
agencies now at work under existing physiographical conditions are com¬ 
pletely exhausted, we are not at liberty to assume the existence of dis¬ 
similar physiographical conditions or a different application of the present 
physical agencies. 
There is, however, always great difiiculty in deciding absolutely 
what species are indigenous and what species are introduced in any 
locality, and here no species will be considered “indigenous” for which it 
is possible to suggest in the remotest fashion any means of introduction. 
At the risk therefore of including among introduced species many that 
are probably quite entitled to be termed indigenous, the possibilities are 
discussed under the headings of the various active introducing agencies. 
As this involves a use of the terms “ indigenous ” and “ introduced ” 
somewhat different from the sense in which they are generally accepted, 
it seems better that the possibly introduced species be spoken of as 
“migrant”; and the certainly indigenous residuary species termed 
“ remanent,” many of the “ migrant ” species being doubtless perfectly 
“ indigenous ” in the generally received sense. 
Even within the group of “ migrant ” species difficulties often arise 
owino- to certain species being assisted in one way from island to island 
° 175 
