bare hot rocks, and tenantless, steam-emitting seas, of the previous time. Under a gray, opaque sky, in which neither sun nor moon appear, we are not unfrequently presented with a varied drapery of clouds,--a drapery varied in form, though not in color: bank often seems piled over bank, shaded beneath and lighter above; or the whole breaks into dappled cloudlets, which bear--to borrow from the poetic description of Bloomfield--the "beauteous semblance of a flock at rest." And if such ærial draperies appeared in this early period, with the clear space between them and the earth which we so often see in gray, sunless days, the optical aspect must have been widely different from that of the previous time, in which a dense vaporous fog lay heavy upon rock and sea, and extended from the earth's surface to the upper heights of the atmosphere. The third day's vision seems to be more purely geological in its character than either of the previous two. Extensive tracts of dry land appear, and there springs up over them, at the Divine command, a rank vegetation. And we know that what seems to be the corresponding Carboniferous period, unlike any of the preceding ones, was remarkable for its great tracts of terrestrial surface, and for its extraordinary flora. For the first time dry land, and organized bodies at once bulky enough, and exhibited in a medium clear enough, to render them conspicuous objects in a distant prospect, appear in the Mosaic drama; and we still find at once evidence of the existence of extensive though apparently very flat lands, and the remains of a wonderfully gigantic and abundant vegetation, in what appear to be the rocks of this period. The vision of the fourth day, like that of the second, pertained not to the earth, but to the _heavens_; the sun, moon, and stars become visible, and form the sole subjects of the prophetic description. And just as, during the second period, the earth would in all probability have failed to furnish any feature of mark enough to divert a human eye placed on a commanding station from the conspicuous _atmospheric_ phenomena of the time, so it seems equally probable that during this fourth period it would have failed to furnish any feature of mark enough to divert a human eye from the still more conspicuous _celestial_ phenomena of the time. As has been already incidentally remarked, the Permian and Triassic periods were "epochs"--to employ the language of the late Professor Edward Forbes--"of great poverty of production of generic types." On the other hand, the appearance for the first time of sun, moon, and stars, must have formed a scene well suited to divert the attention of the seer from every other. Nor (as has been somewhat rashly argued by Dr. Kitto and several others) does it seem irrational to hold that three very extended _periods_ should have elapsed ere the sidereal heavens became visible on earth. Addison's popular illustration, drawn