It only serves to make the matter less intelligible, that there _are_ found in Secondary strata some few relics of birds with decidedly saurian characteristics,[198] as the _Hesperornis_ and _Ichthyornis_ in the Chalk, and the _Archæopteryx_, most ancient of fowls, lower still, in the Oolite. All these creatures have lizard-like heads and teeth; the _Archæopteryx_ in addition has decidedly reptilian characters connected with its wings and tail. But none of them throw the slightest light upon the point we are now considering. In the case of all, the problem of flight has been completely solved. Their wings are no rudimentary structures half way between legs and wings, but as finished productions as those of to-day. As Professor Huxley acknowledges, if the skeletons of _Hesperornis_ and _Icthyornis_ had been found without their skulls, they would probably have been classed without more ado amongst existing birds. The latter "has, [he tells us,] strong wings, and no doubt possessed corresponding powers of flight." The wings of _Hesperornis_, he says, resemble those of our divers and grebes, and were probably used, like theirs, chiefly for swimming.[199] As for the _Archæopteryx_, its reptilian features notwithstanding, it is a perfectly-appointed bird. As Sir Richard Owen testifies,[200] its wing, despite the peculiarities mentioned, is completely developed as to all essentials. Nor does even this member furnish the creature with its most bird-like characteristics,--but the keeled breast-bone, so intimately connected with the requirements of flight,--and, still more markedly, the feet. Professor Huxley writes: "The feet are not only altogether bird-like, but have the special character of the feet of perching birds; while the body had a clothing of true feathers." Thus, to whatever these Saurian birds may testify,--and the extreme importance of their evidence none will question--they no more serve to bridge the gulf between reptiles and birds, than a group of volcanic islets like the Azores bridges the Atlantic, for they supply no vestige of a continuous way from one term to the other. Rather, they do but enhance the mystery of the transformation, to the manner of which, despite their composite features, they furnish no clue.