182 The Queensland Naturalist. Vol. I. 
land, Germany, Austria, Italy, etc., are we not justified 
in saying that the molluscan fauna of the European Pliocene 
sea is as well known as that of the North Sea of the present 
day ? Here, surely we have to strain language to find 
imperfection in the geological record. I will not enlarge 
upon this portion of the subject ; your own observation 
and reading will supply sufficient illustrations. But I 
would, in passing, note a bit of valuable negative evidence. 
Searles Wood in all this opulence of shells found no trace 
of a Nautilus. Is it not fairer to infer that these cephalopods 
did not live in that Pliocene sea, than to assume that they 
did and have not been found ? Negative evidence of a 
certain kind, used judicially, becomes positive evidence. 
But it is a dangerous weapon save in skilled hands. 
21. — Of course, you will say it is not in a single forma- 
tion that we find great breaks, but in the unconformities 
between formations. This is noon-day clear. But I 
shall proceed to prove there is exactly the same class of 
lacuna in the palaeontology of a homogenous stratum 
as we find in an unconformity. Neither supply the kind 
of evidence the Darwinian relies upon. 
22. — I want to show you there is in many cases clear 
evidence of unbroken physical continuity with absolutely 
broken palaeontological continuity. Wliere we get a strong 
unconformity, as between the Cretaceous and Tertiary 
in England, accompanied (as it always is) with a great 
change of fauna, we are justified in appealing to the 
imperfection of the geological record as the reason why the 
intermediate forms are absent. So, too, when we find 
distinct faunas in two conformable beds, say a sandstone 
and a limestone, Ave are correct in ascribing the phenomena 
to the differing physical conditions. 
23. — But Avhat is the explanation Avhen we have the 
same physical conditions, absolutely continuous so far as 
structure is concerned, and yet a change of fauna ? AIIoav 
me again to use European illustrations, since the geology 
of Europe has been so much more completely investigated 
than that of Australia. 
24. — We have many formations which are practically 
homogenous in physical structure from top to bottom, 
some a few feet thick, some many hundreds. The Chalk, 
for example, is pretty pure carbonate of lime throughout 
its 1.500 feet of thickness. It is softer at the top than 
lower down ; there are thin seams of “ pip^ clay ” here 
and there a few inches thick. But over thousands of 
square miles there is not as much mechanical difference 
as one sees betAveen high and low water-mark on the shores 
of Moreton Bay. There is no break of any importance. 
Certainly not a break representing those hundreds of 
thousands, or even millions of years DaiAvin Avants for the 
