* * * * * And, here again, there is no vestige of intermediate species, linking dicotyledonous plants with other types. No trace of a plant belonging to this great division has yet been detected in any earlier stratum [than the upper chalk]. There is no evidence whatever for Haeckel's statement that the _Apetalæ_ probably existed in the Triassic and Jurassic periods.... It cannot be doubted that the conditions favourable to the preservation of Monocotyledons and Equisetums would have secured the preservation of some of the _Apetalæ_, had they existed. This absence can be accounted for only on the supposition that they formed no part of the then existing vegetation. And in the deposits older than the Trias, or in any subsequent deposits, no intermediate form has been detected,--no Gymnosperm or Monocotyledon which exhibits in any point of its structure a modification towards the more highly organized Dicotyledon. * * * * * Nor, on the same authority, is this all. It is equally important in its bearing on the hypothesis of genetic evolution that the generic groups above named have persisted from the first known appearance of Dicotyledons, throughout the whole of the intervening ages, and still hold their places unchanged among the existing forms of vegetation. The persistence of generic and specific types, and the certain knowledge we possess of the life of many existing species of Phanerogams and Cryptogams which have come down through the Glacial Epoch, have not been sufficiently considered in their bearing on the hypothesis. We have already seen something of an example which illustrates this point in a remarkable manner,--that of _Salix polaris_, the willow which has so obstinately preserved its specific identity amid great stress of circumstances. It belongs to a very variable genus--one in which if anywhere evidence of genetic development might be looked for. Yet it is found that since a period prior to the great Ice Age, or Glacial epoch, it has remained absolutely unchanged. At such a rate, we cannot but ask, how long would Evolution take to get back to the generalized type-form, or common ancestor, of the genus _Salix_, and then to that of the Order _Salicineae_, which includes poplars as well as willows. "The Ordinal form, if it ever existed, must necessarily be much older than the period of the upper Cretaceous rocks, that is than the period to which the earliest known Dicotyledons belong." And it is obvious that when we had got back to the parental stock of the willow tribe, we should still, as evolutionists, be separated by a gulf still vastly greater from the common ancestor of all Dicotyledons, of oaks, apple-trees, primroses, and daisies no less than of willows and poplars. The significance of all these various facts is thus summed up: