322 NATURAL SCIENCE [November 
series of stratified rocks in a continuous chain and to unerringly 
distinguish any particular horizon in discussion by its particular 
ear mark, namely, the special fauna and flora whose debris are 
found in it. 
This I need not say is the corner stone of modern strati- 
graphical geology, and this, so far as we can see it, will remain. 
I have nothing to say about the key which is an absolutely in- 
dispensable one. What I propose to criticise, however, is the 
arrangement founded upon the facts thus ascertained, and I 
propose to attack it in two ways and on two grounds. If our 
object is to ascertain the past sequence of events in any particular 
spot on the earth’s surface, we cannot do better than make a boring 
at the particular spot and describe in detail the successive beds 
lying upon one another or which we can fairly conclude once lay 
upon one another in that particular spot. This will undoubtedly, 
so far as that spot is concerned, give us the sequence of events. 
If the record be complete it will, of course, be a complete story. 
If some pages be torn out of the book it will, of course, be in- 
complete. This we may or we may not be able to infer. What 
is clear is that the column of different strata thus pierced represents 
not a general universal geological pedigree, but the geological 
pedigree of one particular spot only. ‘This, of course, is universally 
admitted. No fact is more elementary than that two wells dug 
in the same parish may present us with very different columns 
of strata. Some thin out, some grow thicker, some disappear, 
and some make their appearance. The one cardinal fact, however, 
remains, that so long as we remain in the same “ Zoological 
Province” so long will these beds when found together be found 
arranged in the same order. 
This being so it is perfectly justifiable and perfectly logical so 
long as we remain in the same zoological province to collect all the 
beds occurring within that province and to arrange them in 
sequence, and having done so to make that sequence a test and 
touchstone by which the relative position of any particular bed in 
any particular section may be ascertained ; always remembering, 
however, that we do not mean by this arrangement that the 
sequence of events in every spot within this area was precisely the 
same. In some cases certain stages were possibly absent.as the 
record seems to infer, or a particular stage in one area may have 
become a complicated series in another. These are, however, 
matters of detail in which we have no necessity to guard ourselves 
since they are obvious and simple. What it is important to 
remember, and what has been made the subject of adverse comment 
by more than one distinguished palaeontologist, is the fact that the 
arrangement we have been considering only holds good and is alone 
