ead, when
attacked by an enemy, or immediately as it feels the hook in its jaws,
erects its two spines at nearly right angles with the plates of the head,
as if to render itself as difficult of being swallowed as possible. The
attitude is one of danger and alarm; and it is a curious fact, that in
this attitude nine-tenth of the Pterichthyes of the Lower Old Red
Sandstone are to be found."

A century has passed since Miller thought he had discovered a turtle
which was so modified in structure as to be a link between the turtles
and the fish. But to the present day geology has failed to furnish
evidence that such a link at one time existed.

This _absence, in the geological record, of transitional forms,_ is one
of the greatest difficulties of the evolutionistic theory. According to
the theory, the fossils found in the various layers of rock ought to
show gradual modifications, linking the various species of animals and
plants in a finely graduated system, with thousands of forms showing in
rudimentary structure those organs which in the more advanced forms
have become fully developed. However, no such progress from more to
less generalized types has been demonstrated, although many trained
investigators have searched the fossiliferous rocks for such evidence
of evolution. Professor Huxley in his _"Lay Sermons"_ admits that an
impartial survey of the positively ascertained truths of paleontology
"Either shows us no evidence of such modification, or demonstrates
such modification as has occurred to have been very slight; and as to
the nature of that modification, it yields no evidence whatsoever that
the earlier members of any long-continued group were more generalized in
structure than the later ones." LeConte says: "Although the species
change greatly, and perhaps many times, in passing from the lowest to
the highest strata, we do not usually, it must be acknowledged, find the
gradual transitions we would naturally expect, if the change were
effected by gradual transitions." He further speaks of the absence of
connecting links as "the greatest of all objections" against the theory
of evolution. (_"Evolution,"_ p. 234.) This absence of transitional
forms between different species has always been recognized as a serious
difficulty; and Mr. Darwin, in the attempt to obviate it, succeeds only
in showing how very serious it is. These are his words: "Geology
assuredly does not reveal any such finely graduated organic chain; a