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1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1861
1869
1872

distinct 1859 1860 1861 1866
new and distinct 1869
new, though closely allied 1872

plainly leads to the 1861 1866 1869 1872
leads me to 1859 1860

though only some of them, which 1866 1869 1872
which 1859 1860 1861

During the periods of
subsidence
subsidence,
there would probably be much extinction of life; during the periods of elevation, there would be much variation, but the geological record would then be
less
least
perfect.
It may be doubted whether the duration of any one great period of subsidence over the whole or part of the archipelago, together with a contemporaneous accumulation of sediment, would
exceed
exceed
the average duration of the same specific forms; and these contingencies are indispensable for the preservation of all the transitional gradations between any two or more species. If such gradations were not
fully
all fully
preserved, transitional varieties would merely appear as so many distinct species. It
is,
is
also,
also
probable that each great period of subsidence would be interrupted by oscillations of level, and that slight climatal changes would intervene during such lengthy periods; and in these cases the inhabitants of the archipelago would
have to
....
migrate, and no closely consecutive record of their modifications could be preserved in any one formation.
Very many of the marine inhabitants of the archipelago now range thousands of miles beyond its confines; and analogy plainly leads to the
believe
belief
that it would be chiefly these far-ranging
species
species,
though only some of them, which would oftenest produce new varieties; and the varieties would at first
generally
generally
be local or confined to one place, but if possessed of any decided advantage, or when further modified and improved, they would slowly spread and supplant their parent-forms. When such varieties returned to their ancient homes, as they would differ from their former
state
state,
in