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346 THE CAUSES OF THE XI 
in their continuity, or any very great distance 
between the points to be compared. 
Well now, so much for the record itself—so 
much for its imperfections,—so much for the con- 
ditions to be observed in interpreting it, and its 
chronological indications, the moment we pass 
beyond the limits of a vertical linear section. 
Now let us pass from the record to that which it 
contains,—from the book itself to the writing and 
the figures on its pages. This writing and these 
figures consist of remains of animals and plants 
which, in the great majority of cases, have lived 
and died in the very spot in which we now find 
them, or at least in the immediate vicinity. You 
must all of you be aware—and I referred to the 
fact in my last lecture—that there are vast 
numbers of creatures living at the bottom of the 
sea. These creatures, like all others, sooner or 
later die, and their shells and hard parts lie at 
the bottom; and then the fine mud which is 
being constantly brought down by rivers and the 
action of the wear and tear of the sea, covers 
them over and protects them from any further 
change or alteration ; and, of course, as in process: 
of time the mud becomes hardened and solidified, 
the shells of these animals are preserved and 
firmly imbedded in the limestone or sandstone 
which is being thus formed. You may see in the 
galleries of the Museum up stairs specimens 
limestones in which such fossil remains of existing” 
