This conception is one which harmonizes completely with the views here advocated, and with those of Mr.Herbert Spencer, who also calls in direct modification to the aid of "Natural Selection." That merely minute, indefinite variations in all directions should unaided have independently built up the shoulder structure of {73} the pterodactyles and carinate birds, and have laterally depressed their optic lobes, at a time so far back as the deposition of the Oolite strata,[56] is a coincidence of the highest improbability; but that an innate power and evolutionary law, aided by the corrective action of "Natural Selection," should have furnished like needs with like aids, is not at all improbable.

The difficulty does not tell against the theory of evolution, but only against the specially Darwinian form of it.

Now this form has never been expressly adopted by Professor Huxley; so far from it, in his lecture on this subject at the Royal Institution before referred to, he observes,[57] "I can testify, from personal experience, it is possible to have a complete faith in the general doctrine of evolution, and yet to hesitate in accepting the Nebular, or the Uniformitarian, or the Darwinian hypotheses in all their integrity and fulness." [Illustration: THE ARCHEOPTERYX (of the Oolite strata).] It is quite consistent, then, in the Professor to explain the {74} difficulty as he does; but it would not be similarly so with an absolute and pure Darwinian.
Yet stronger arguments of an analogous kind are, however, to be derived from the highest organs of sense.

In the most perfectly organized animals--those namely which, like ourselves, possess a spinal column--the internal organs of hearing consist of two more or less complex membranous sacs (containing calcareous particles--otoliths), which are primitively or permanently lodged in two chambers, one on each side of the cartilaginous skull.

The primitive cartilaginous cranium supports and protects the base of the brain, and the auditory nerves pass from that brain into the cartilaginous chambers to reach the auditory sacs.