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See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1861
1866
1872

→ are the descendants of 1866 1869 1872
have descended from 1859 1860 1861
→ which constitute the several species of the 1866 1869
constituting the six 1859 1860 1861
which constitute the 1872
→ genera; 1866 1869
genera. 1859 1860 1861
genera containing the several species; 1872
→ each 1869 1872
the 1859 1860 1861
each of the 1866
→ genus having 1869 1872
genera have all 1859 1860 1861
genera having 1866
→ and this probably will 1869
which would probably 1859 1860 1861
and this probably would 1866
and this will 1872
size and in
other
all other
characters to the species still living in South America; and some of these fossils may
have been
be
the actual progenitors of
the living
living
species. It must not be forgotten that, on
my
our
theory, all the species of the same genus →are the descendants of some one species; so
that
that,
if six genera, each having eight species, be found in one geological formation, and in
the next
a
succeeding formation there be six other allied or representative genera
with
each with
the same number of species, then we may conclude that
only
generally only
one species of each of the
six
....
older genera has left modified descendants, →which constitute the several species of the new →genera;
The
the
other seven species of →each old →genus having died out and
have
....
left no progeny. Or, →and this probably will be a far commoner case, two or three species
of
in
only two
two
or three
alone
alone
of the six older genera will
have been
be
the parents of the
six
....
new
genera;
genera:
the other
old
....
species and the other
old whole
whole
old genera
genera
having become utterly extinct. In failing orders, with the genera and species decreasing in
numbers
numbers,
as
apparently
....
is the case
of
with
the Edentata of South America, still fewer genera and species will
have left
leave
modified blood-descendants.
Summary
Summary
of
of
the
the
preceding
preceding
and
and
present
present
Chapters .—
Chapters. —
Chapter. —
Chapter .
Chapters .
Chapter .
I have attempted to show that the geological record is extremely imperfect; that only a small portion of the globe has been geologically explored with care; that only certain classes of organic beings have been largely preserved in a fossil state; that the number both of specimens and of species, preserved in our museums, is absolutely as nothing compared with the
incalculable
....
number of generations which must have passed away even during a single formation; that, owing to subsidence being
necessary
almost necessary
for the accumulation of
fossiliferous
....
deposits