BY SYDNEY B. J. SKERTCHLY. 65 
35. A theory might be true, and yet there be so many 
gaps in the evidence that it was unprovable, and it was 
lawful to say, “Wait for more evidence: it is the im- 
perfection of the geological record that is in fault, not the 
theory.” But if the theory be sound, each new discovery 
will narrow the gaps: if unsound it will widen them. It 
cannot be claimed that this test has worked out satisfactorily 
for many of the pet side-shows of the theory of Evolution. 
36. For instance: our knowledge of fossil mammalia 
has vastly increased of late years, and many minor gaps 
have been filled in. But the greater gaps are more gaping 
than ever. We know, for example, a great deal about the 
fossil pedigree of horses: but we are farther off than ever 
from knowing the ancestry of the Equiidae. Still more 
remote seems any hope of perfecting the genealogical tree 
of the Mammalia. The old saw about Nature not moving 
by leaps seems to be losing its teeth. 
37. When Wallace wrote his “Island Life” it was 
quite reasonable for him to hope, and write as if the future 
would reveal, the ancestors of our Marsupials in the rocks 
of Australia. The appeal to imperfection has lost its 
force to-day. We have explored the Australian and Tas- 
manian Tertaries pretty completely, and found them 
very rich in plant remains. Yet have we never found a 
trace of any land mammal at all. True, this is negative 
evidence: but if such creatures did not exist, what other 
than negative evidence is possible? Surely the negative 
evidence of every fisherman who has speared, or netted, 
or angled for, or poisoned, or dynamited fish in the Brisbane 
River is good evidence of the non-existence of trout in the 
stream ! 
38. When we get to Pliocene times, Marsupial remains 
are plentiful enough, showing there was no difficulty about 
their preservation. The fact is that the Marsupial was 
not in Australia ; and as none of his remains are found else- 
where, and as he has no living representative outside the 
Australian area, the only logical inference is that he is of 
Australian origin, and of recent date at that. But we 
shall have to say more on this point presently. The Ameri- 
can opposums, we shall see, are out of court. 
39. The conclusion forced upon me is that both our 
H—Royat Soc. 
