I.—INTRODUCTION. 15 
} Joo t} obtained, 2a. gh mae Be | Pate 
by Dowling. T 
complete, is nevertheless wr The vegetation of Chittagong 
may be said to be mainly that characteristic of Arracan, with, how- 
ever, as might be expected, a considerable admixture of species 
a of Cachar and Khasia, and with not a few special 
form 
Of Tipper era we know even less than we do of Orissa. What we 
do know of the level and the submontane north-western portion we 
mainly owe to Clarke. Taken by themselves, these lower tracts 
might be considered no more than a portion of Eastern Bengal, 
with an unusual admixture of species characteristic of Silhet. But 
this Silhet element in the flora is sufficiently vee to make it 
convenient to deal with this tract, the Comilla district, apart from 
Be and to treat it in connection with its own highlands. As 
regards these highlands, we know little beyond what is to be 
learned from the work of Roxburgh os et name: Hamilton, 
done eighty to a hundred years ago. n, indeed, appears to 
be the only botanist who has ane rae hills of ‘‘ Southern 
Tripura.” Few of Hamilton’s specimens, and none of his Tippera 
ones, are now in India. Roxburgh’s specimens, too, are gone, but 
fortunately India has not been robbed of his drawings, a number of 
which represent interesting and, but for these drawings, still un- 
known plants from Hill Tippera. What we do know of the vege- 
tation of these Tippera hills indicates that in the northern parts it 
is an extension of the flora characteristic of the Bhuban and other 
ranges of hills in Cachar and South Silhet, outliers of the Lushai 
range; in the southern parts the flora is a repetition, with variations, 
of the vegetation of Chittagong. 
The Lower Gangetic Plain, or Bengal proper, which from the 
uniiosanity: of its configuration a be expected to oxbilis 1 a 
Lotin 
for mity OL 
so dignewdsat as ce demand further sabdivisions Fortanately, iten 
examined in detail, the area is found to lend itself naturally to our 
purpose. That portion of the Gangetic delta nearest to the sea, an 
intricate system of sea-creeks and half-formed islands, densely 
clothed with a tidal forest of a purely Malayan type, separates 
itself spontaneously from the alluvial rice-plain to the north, 
where the river-banks at least are higher, where tanks can be 
dug that will retain fresh-water, and where only the larger streams 
