dvantage over most of the other species of the
genus. Their modified descendants, fourteen in number at the
fourteen-thousandth generation, will probably have inherited some of
the same advantages: they have also been modified and improved in
a diversified manner at each stage of descent, so as to have become
adapted to many related places in the natural economy of their country.
It seems, therefore, to me extremely probable that they will have taken
the places of, and thus exterminated, not only their parents (A) and
(I), but likewise some of the original species which were most nearly
related to their parents. Hence very few of the original species will
have transmitted offspring to the fourteen-thousandth generation. We may
suppose that only one (F), of the two species which were least closely
related to the other nine original species, has transmitted descendants
to this late stage of descent.

The new species in our diagram descended from the original eleven
species, will now be fifteen in number. Owing to the divergent tendency
of natural selection, the extreme amount of difference in character
between species a14 and z14 will be much greater than that between
the most different of the original eleven species. The new species,
moreover, will be allied to each other in a widely different manner. Of
the eight descendants from (A) the three marked a14, q14, p14, will be
nearly related from having recently branched off from a10; b14 and
f14, from having diverged at an earlier period from a5, will be in some
degree distinct from the three first-named species; and lastly, o14,
e14, and m14, will be nearly related one to the other, but from having
diverged at the first commencement of the process of modification, will
be widely different from the other five species, and may constitute a
sub-genus or even a distinct genus.

The six descendants from (I) will form two sub-genera or even genera.
But as the original species (I) differed largely from (A), standing
nearly at the extreme points of the original genus, the six descendants
from (I) will, owing to inheritance, differ considerably from the eight
descendants from (A); the two groups, moreover, are supposed to have
gone on diverging in different directions. The intermediate species,
also (and this is a very important consideration), which connected the
original species (A) and (I), have all become, excepting (F), extinct,
and have left no descendants. Hence the six ne