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rocks on the earth’s surface—a fact which is too often over- 
looked—and they are only of local value where the breaks 
or limits of characteristic life and stratigraphical connection 
can be seen to coincide. 
Conclusions from Paleontology, based upon the association 
of typical organisms with typical rocks in one part of the 
earths surface, certainly form a strong presumption in favour 
of their application in a distant part of the earth where such 
combined associations seem to harmonise, and no doubt in 
a large measure this holds good, but they are also apt, by force 
of preconception, to mislead the Palzontologist where the 
evidences of Stratigraphy are obscure or in conflict. Nothing 
has so strongly demonstrated the value of Jukes’ cautions as 
a field geologist, in the consideration of such matters, as the 
discovery of the existence in Australia cf a land flora of 
European Mesozoic aspect, interstratified with a marine fauna 
of a distinctly marked European Paleozoic facies. It is not 
without advantage that mistakes were made by/Paleontologists 
over this question, for it has profitably warned us that, in all 
such matters, we are too apt to crystalise opinion ; to fall back 
upon an old locally useful generalisation, rather than be at 
the trouble to readjust the true relations of fresh facts 
and fresh combinations in areas far removed from the centre 
where the first generalisation was formed, and where, probably, 
it still holds good. Much unnecessary warmth of controversy 
between able and well-informed authorities might have been 
obviated hitherto if questions regarding centres of origin 
had received due attention in a broad and philosophical spirit 
when discussing the new facts and relations in Stratigraphy 
and Paleontology, which at first sight seemed to be evidences 
of “ conflicting testimonies of the rocks.” It cannot be too 
frequently asserted that the associated facts of stratigraphic 
and organic relation in one part of the world can never be 
severed or successfully subordinated by generalisations or 
deductions, however skilfully made, from  dissimiliarly 
associated facts or relation in another distant part of the 
world ; and it is this conviction, enforced by the difficulties of 
local experience in the investigation of Tasmanian geology, 
extending now over a period of 15 years, which induces me 
to concur with Mr. Jukes (p. 22, “Sketch of the Physical 
Structure of Australia, 1850”) in the statement that, 
before we can rest satisfied with “existing classification of 
the rocks of Carboniferous, Permian, or Mesozoic age, we must 
study more thoroughly many questions, such as the 
original centre of production of the animals (or plants), and 
the time necessary for their migration and general spreading 
over the globe. Whether they might not have become ex- 
tinct at the spot where they first began to exist before they 
