During the twenty-one years, too, as Huxley likewise pointed out, an immense number of new facts had come to strengthen the hands of the evolutionists at the very point where they had before felt themselves most openly vulnerable. Palæontology had supplied many of those missing links in the organic chain whose absence from the interrupted and imperfect geological record had been loudly alleged against the Darwinian hypothesis in the earlier days of struggle and hesitation. Two years after the publication of the 'Origin of Species,' the discovery of a winged and feathered creature, happily preserved for us in the Solenhofen slates, with lizard-like head and teeth and tail, and bird-like pinions, feet, and breast, had bridged over in part the great gap that yawns between the existing birds and reptiles. A few years later, new fossil reptilian forms, erect on their hind legs like kangaroos, and with very singular peculiarities of bony structure, had helped still further to show the nature of the modifications by which the scale-bearing quadruped type passed slowly into that of the feather-bearing biped. In 1875, again, Professor Marsh's discovery of the toothed birds in the American cretaceous strata completed the illustrative series of transitional forms over what had once been the most remarkable existing break in the continuity of organic development. Similarly, Hofmeister's investigations in the vegetable world brought close together the flowering and flowerless plants, by indicating that the ferns and the horsetails were connected in curious unforeseen ways, through the pill-worts and club-mosses, with the earliest and simplest of forest trees, the firs and the puzzle-monkeys. In minor matters like progress was continually reported on every side. Gaudry found among the fossils of Attica the successive stages by which the ancient and undeveloped civets passed into the more modern and specialised tribe of the hyænas; Marsh traced out in Western America the ancestry of the horse from a five-toed creature no bigger than a fox, through intermediate four-toed and three-toed forms, to the existing single solid-hoofed type with its digits reduced to the minimum of unity; and Filhol unearthed among the phosphorites of Quercy the common progenitor of the most distinct among the recent carnivores, the cats and the dogs, the plantigrade bears and the digitigrade pumas. 'So far as the animal world is concerned,' Professor Huxley said in conclusion, reviewing these additions to the evidence upon that memorable occasion, 'evolution is no longer a speculation but a statement of historical fact.' Of Darwin himself he remarked truly, 'He has lived long enough to outlast detraction and opposition, and to see the stone that the builders rejected become the head-stone of the corner.'