they were specially
adapted to make progress. They lived through "Paleozoic" time, which,
according to Dana, represents twelve of the sixteen parts of all
geological time, beginning with the Primordial; or, calling the whole
geological time 48 millions of years, the trilobites lived 36 million of
years, or three-fourths of all geological time. From their great
persistence in time (accepting, for the sake of argument, the "ages" of
speculative geology) it would seem that they had a remarkably good
opportunity to make wonderful progress in structure. During that time
there were thousands of species, yet they made no progress. We do not
know that in all those "millions of years" a single higher form was
evolved from any one of the great multitude of species of trilobites. As
Darwin says of the goose, so one may say of the trilobite; it "had a
singularly inflexible organization." The remarkable thing about this,
however, is that previous to the "Primordial," while it was becoming a
trilobite, it must have had a singularly flexible organization, otherwise
it could not have obtained its complex structure; but when it reached the
"Primordial" it became very conservative.

Fairhurst says, in the work already quoted:

"It is a most remarkable fact that in the first geological period in
which undoubted fossils occur, all the sub-kingdoms except that of the
vertebrates are well represented, and that there is no evidence from
fossils that one sub-kingdom, or even that different classes of the same
sub-kingdom were evolved from each other. The great gulfs that separate
the animal kingdom into sub-kingdoms and classes existed then, and have
continued till the present time.... If we rely on known fossils as
evidence, we would be obliged to conclude that highly organized fishes
were suddenly introduced. The break in the supposed chain of evolution
between the invertebrates and the highly organized vertebrates of the
Lower Silurian is one of the greatest in the whole geological record. The
vast gulf between these structures must, I think, remain unbridged except
by the imagination."

The late Prof. Joseph LeConte, of the University of California, writes
in his book, "Religion and Science:" "The evidence of geology to-day is
that species seem to come in suddenly and in full perfection, remain
substantially unchanged during the term of their existence, and pass
away in full perfection. Other species take their places apparently by
sub