The first and most obvious flaw, in the evolutionary interpretation of fossil series, is the confounding of succession with filiation. Thinkers, from time immemorial, have commented on the deep chasm of distinction, which divides historical from causal sequence, and philosophers have never ceased to inveigh against the sophistical snare of: _Post hoc, ergo propter hoc._ That one form of life has been subsequent in time to another form of life is, in itself, no proof of descent. “Let us suppose,” says Bather, “all written records to be swept away, and an attempt made to reconstruct English history from coins. We could set out our monarchs in true order, and we might suspect that the throne was hereditary; but if on that assumption we were to make James I, the son of Elizabeth—well, but that’s just what palæontologists are constantly doing. The famous diagram of the Evolution of the Horse which Huxley used in his American lectures has had to be corrected in the light of the fuller evidence recently tabulated in a handsome volume by Prof. H. F. Osborn and his coadjutors. _Palæotherium_, which Huxley regarded as a direct ancestor of the horse, is now held to be only a collateral, as the last of the Tudors were collateral ancestors of the Stuarts. The later _Ancitherium_ must be eliminated from the true line as a side branch—a Young Pretender. Sometimes an apparent succession is due to immigration of a distant relative from some other region—‘The glorious House of Hanover and Protestant Succession.’ It was, you will remember, by such migrations that Cuvier explained the renewal of life when a previous fauna had become extinct. He admitted succession but not descent.” (_Science_, Sept. 17, 1920, p. 261.)