elxviii Proceedings of the Asiatic Soc. of Bengal. [N.S., XVII, 
The work of naming and describing these comparatively 
recent plants, although difficult, is none the less important, 
for itis here that we find the immediate ancestors of the domi- 
nant vegetation of to-day. To those interested in the causes of 
the present—in many cases very peculiar—geographical dis- 
tribution of plants, the study of Tertiary and Post-Tertiary 
floras will serve as a particularly sound basis for speculation. 
This line of investigation may throw a welcome light upon the 
question, recently brought into prominence through the work 
of Dr. J. C. Willis and others, as to whether the wide geo- 
graphical distribution of a species at the present day may be 
taken, apart from other considerations, as a sign of the antiquity 
of its origin. 
The most important Tertiary plant-remains are the petrified 
woods, which appear to belong almost entirely to angiospermous 
plants, chiefly dicotyledons and palms. Dicotyledonous woods 
are extraordinarily abundant in the Irrawady System of Upper 
Burma (Theobald 1869 ; Cotter 1908, 1909; Holden 1916) which 
was consequently for many years known as the ‘’ Fossil Wood 
Group,”’ till similar fossils were recently discovered also ia the 
underlying Pegu System (Stuart 1910). These fossil woods of 
rom the Siwalik system near Hardwar and a number of other 
localities (Wadia 1919, pp. 235, 237). Some badly preserved 
coniferous wood was described long ago by Dr. Schleiden from 
the Cuddalore Sandstones of Trivicary under tne name Peuce 
Schmidiana (Schmid und Schleiden 1855, p. 36). 
Impressions of net-veined leaves, presumably of dicoty- 
ledons, have been recorded from the Ranikot Series (Eocene) 
of Sind (see Wadia 1919, p. 215), and from the Laki Series (also 
Eocene) of Baluchistan, Bikaner, Jammu, the Salt Range, 
Burma and Assam (see Wadia 1919, p. 216). In the shaly beds 
of the Siwalik system numerous leaf-impressions have been 
discovered. From the Middle Tertiary beds of Assam Prof. 
Seward described in 1912 a few net-veined leaves which he 
assigned to the artificial genus Phyllites (Seward 1912'), and 
these constitute almost the only published descriptions of Indian 
Tertiary leaf-impressions. 
e only other descriptions of the kind, known to me, 
are those of certain palm leaves assigned to the recent genus 
’ 
