“But in one particular sense the more recent forms must, on my theory, be higher than the more ancient.”

Again:-

“Agassiz insists that ancient animals resemble to a certain extent the embryos of recent animals of the same classes; or that the geological succession of extinct forms is in some degree parallel to the embryological development of recent forms. . . .  This doctrine of Agassiz accords well with the theory of natural selection” (p. 338).

“The theory of natural selection” became “our theory” in 1869.  The opinion of Agassiz accords excellently with the theory of descent with modification, but it is not easy to see how it bears upon the fact that lucky races are preserved in the struggle for life—­which, according to Mr. Darwin’s title-page, is what is meant by natural selection.

Again:-

“On the theory of descent with modification, the great law of the long-enduring but not immutable succession of the same types within the same areas, is at once explained” (p. 340).

Again:-

“It must not be forgotten that, on my theory, all the species of the same genus have descended from some one species” (p. 341).

“My theory” became “our theory” in 1869.

Again:-

“He who rejects these views on the nature of the geological record, will rightly reject my whole theory” (p. 342).

“My” became “our” in 1869.

Again:-

“Passing from these difficulties, the other great leading facts in palaeontology agree admirably with the theory of descent with modification through variation and natural selection” (p. 343).

Again:-

The succession of the same types of structure within the same areas during the later geological periods ceases to be mysterious, and is simply explained by inheritance (p. 345).

I suppose inheritance was not when Mr. Darwin wrote considered mysterious.  The last few words have been altered to “and is intelligible on the principle of inheritance.”  It seems as though Mr. Darwin did not like saying that inheritance was not mysterious, but had no objection to implying that it was intelligible.

The next paragraph begins—­“If, then, the geological record be as imperfect as I believe it to be, . . . the main objections to the theory of natural selection are greatly diminished or disappear.  On the other hand, all the chief laws of palaeontology plainly proclaim, as it seems to me, that species have been produced by ordinary generation.”