PRESIDENT S ADDRESS. 
1813 
comiitions which had preceded, and under which the Lepido- 
dendron flora liad flourished. Unable to endure this alteration, 
the older type of vegetation entirely disappeared from the southern 
hemisphere, being replaced in favourable positions, such as the 
East Australian region, by Antarctic forms, Avhich, collectively, 
1 shall call the Glossopteris flora. 
For long Geological periods this retained its hold upon the 
countries which it had occupied, sometimes so luxuriant under 
“ecpiable, moist and temperate conditions,” as to produce many 
great series of coal seams, but also, at intervals and in particular 
localities, checked by the recurrence of an extreme climate. 
Many alternations of elevation and subsidence took place in the 
meanwhile, but at last (after the formation of the Newcastle Coal) 
a change occurred, at a time when l>oth S. Africa and Australia 
were united by the Antarctic continent, which gradually put an 
end to the existence of Glossopteris in these regions, and in 
course of time replaced it by Teeniopteris, Thinnfeldia, & c. 
This alteration is recorded in S. Africa by the space between 
the Beaufort and Stormberg beds, in New South Wales by tluf 
interval between the Newcastle and Clarence River series, in 
^'ictoria by the Bacchus Marsh beds, and in Queensland and 
. Tasmania by broken series of changing character, as at Burruin 
and Jerusalem, which lead gradually to the coal measures of 
Ipswich, and of various localities in Tasmania, to the Victorian 
(,'arbonaceous series, and to the Clarence River beds of New South 
i Wales. 
In iKitli Queensland and Tasmania this latest coal is found in 
small detached basins, which olTer no evidence as to superposition 
to the surveyor, and can only be {)rovisionally arranged by exami- 
nation of their witry scanty flora. It would therefore appc*ar that 
subsequent p<!riods of excessive rainfall h;d to the silting up of 
these w^veral basins, and also to the erosion of the bars or natural 
115 
