266 
FLORA OF THE SUNDRIBUNS. 
Distributed westward only (India and Ceylon) ... 2 
Undistributed {Oheronia Gammiei^ Cirrhopetalum Roxburghii, 
Pteris vittata) ........ 3 
The number of Indo-Chinese species that the Sundribuns share 
with Sikkim, which cannot, however, be regarded as a western region, 
is rather striking. It is not a little remarkable that three of the species 
not hitherto collected anywhere except in the Sundribuns should be 
species of a class eminently adapted for dispersal by means of an 
agency so constantly active in the area as wind. 
The distribution of the 41 probably river-borne species does not call 
for detailed analysis, and the only remarks that have to be made re- 
garding them turn on the question as to whether their presence in the 
Sundribuns is due to their having been brought down by the Ganges 
or the Brahmaputra. The topography of the region indicates that 
in most cases the Ganges is more likely to have been the agent, though 
with a number of the species either river may 'have been responsi- 
ble, ' while there are a few species, such as Micromeium pubescens, 
Teramnus jiexilis, Eugenia frulicosa^ Conyza semipinnatifidai 
Lippix geminata^ Pandanus f(Btidus^ Deemonorops Jenkinsianusi 
Cyperus inundafus, that, having regard to their known distribution and 
in some cases also to their actual locality in the Sundribuns, we must 
believe to have been brought down by the Brahmaputra and not by 
the Ganges, if this means of dispersal be really responsible for their 
presence in our area. One species, moreover, for which the writer 
assumes tentatively this means of dispersal offers some difficulty. 
This is Cryptocoryne ciliata.^ a species very plentiful in Lower 
Bengal and one that is carried about in this particular manner, by 
upward-flowing tides : it is, however, fair to remark as well as by 
falling ones. The difficulty lies in the fact that this Cryptocoryne is 
confined to Lower Bengal, so far as India is concerned, and as it is 
also a Malayan species, the question arises whether it may not really be, 
as Mr. Clarke considers, a characteristic Sundribun plant, the pre- 
sence of which in India is due to introduction by the sea. The objection 
to this conclusion is, after all, only that it does not appear to enter 
the Sundribun forests, or to establish itself in our area till clearings 
have been effected — a not insuperable objection when the case of 
species like Blamea amplectens var. maritima^ Paspalum distichum, 
Fimhristylis polytrichoides var. halopkila, Solanum trilohatum^ 
Azima tetracantha^ Psilotrichum ferrugineum^ Agyneia bacciformis 
and Sphssranthus africanus are considered. The great difference 
between the Cryptocoryne and these other species lies in its submerged 
habit ; it is easy to understand why the other species mentioned 
should find the conditions of the swamp-forests inimical to their welfare ; 
