PREFACH. 
As the publications of a Geological Survey cannot properly be 
limited to the maps and sections, but would be incomplete without 
figures and descriptions of the fossil organic remains made use of 
for the determination of the geological ages of the different geolo- 
gical formations of the country,* it has been determined to issue a 
‘““Prodromus,” or preliminary publication of the Victorian Organic 
Remains in Decades, or numbers of ten plates each, with corre- 
sponding letterpress, on the plan of the Decades of the Geological 
Survey of England, followed by the Geological Surveys of Canada, 
India, and several other Governments. 
The Decades will contain figures and descriptions in the first 
place of the more characteristic fossils of each formation, of which 
good specimens may be in the National Collection ; so that observers 
in the field may make use of them for preliminary or approximate 
determination of the geological ages of the strata they may meet. 
A portion of the impression of the plates will be kept back until a 
complete systematic treatise on the fossils of each formation may 
be issued when the materials approach completion. 
In this sixth Decade, the first plate illustrates the extinct gigantic 
Kangaroo, Macropus Titan, so common in our superficial Pliocene 
Tertiary deposits ; the predecessor of the “ Old Man” Kangaroo of 
the same localities in our own times. 
* “ Paleontological researches forming so essential a part of geological investigations, such 
as those now in progress by the Geological Survey of the United Kingdom, the accompanying 
plates and descriptions of British fossils have been prepared as part of the Geological Memoirs. 
They constitute a needful portion of the publications of the Geological Survey.”—Sir Henry 
T. De la Beche, Director-General of the Geological Survey of the United Kingdom, in notice 
prefixed to the first of the Decades of the English Geological Survey. 
[3] 
