r Huxley, with a laudable caution and
moderation too little observed by some Teutonic Darwinians, guarded himself
carefully from any imputation of asserting dogmatically the theory of
"Natural Selection," while upholding fully the doctrine of evolution.

But, after all, it is by no means certain, though very probable, that the
Connecticut footsteps were made by very ornithic reptiles, or extremely
sauroid birds. And it must not be forgotten that a completely carinate[128]
bird (the Archeopteryx) existed at a time, when, as yet, we have no
evidence of some of the Dinosauria having come into being. Moreover, if the
remarkable and minute similarity of the coracoid of a pterodactyle to that
of a bird be merely the result of function and no sign of genetic affinity,
it is not inconceivable that pelvic and leg resemblances of Dinosauria to
birds may be functional likewise, though such an explanation is, of {132}
course, by no means necessary to support the view maintained in this book.

[Illustration: THE ARCHEOPTERYX (OF THE OOLITE STRATA).]

[Illustration: SKELETON OF AN ICHTHYOSAURUS.]

But the number of forms represented by many individuals, yet by _no
transitional ones_, is so great that only two or three can be selected as
examples. Thus those remarkable fossil reptiles, the Ichthyosauria and
Plesiosauria, extended, through the secondary period, probably over the
greater part of the globe. Yet no single transitional form has yet been met
with in spite of the multitudinous individuals preserved. Again, with their
modern representatives the Cetacea, one or two aberrant forms alone {133}
have been found, but no series of transitional ones indicating minutely the
line of descent. This group, the whales, is a very marked one, and it is
curious, on Darwinian principles, that so few instances tending to indicate
its mode of origin should have presented themselves. Here, as in the bats,
we might surely expect that some relics of unquestionably incipient stages
of its development would have been left.

[Illustration: SKELETON OF A PLESIOSAURUS.]

The singular order Chelonia, including the tortoises, turtles, and
terrapins (or fresh-water tortoises), is another instance of an extreme
form without any, as yet known, transitional stages. Another group may be
finally mentioned, viz. the frogs and toads, anourous Batrachians, of which
we have at present no relic of any kind linking them on to the Eft group on
the one hand, or