Page:Popular Science Monthly Volume 75.djvu/543

Rh apparently sudden appearance of groups of allied, and by no means absolutely primordial, species in the lowest fossiliferous strata then known. Thirdly, there was the sudden disappearance of whole groups of species at the end of certain geological periods, and their sudden replacement in the next period by species different in type from the former, and closely allied to one another. These two points—the second and third—were the especial contribution of the Cuvierian school to the controversy. Out of Cuvier's doctrine of the abrupt extinction of faunas at the successive "revolutions of the globe," his disciples had elaborated the theory of the radical and world-wide discontinuity of the faunas and floras of the successive great periods, and had hence inferred the actual necessity of assuming a definite number of special creations of fresh organic worlds en bloc. D'Orbigny knew exactly how many such creations there had been:

Fourthly—to continue the enumeration of the paleontological difficulties—it was objected that, especially within the limits of single great geological formations, the arrangement of fossils in the strata did not exhibit the required order of progression from lower to higher types, but sometimes even reversed that order. This was Sedgwick's principal point in his Edinburgh Review article, as it was that of Hugh Miller in his "Footprints of the Creator," 1849, the most widely circulated of the replies to the "Vestiges." Miller's argument may be summarized in his own words. The latest discoveries in the Silurian and Cambrian series, he declared, do not show the

sort of arrangement demanded by the exigencies of the development hypotheses. A true wood at the base of the old red sandstone, or a true Placoid in the limestones of Bala, very considerably beneath the base of the Lower Silurian system, are untoward misplacements for the purposes of the Lamarckian; and who that has watched the progress of discovery for the last twenty years and seen the place of the earliest ichthyolite transferred from the Carboniferous to the Cambrian system, and that of the earliest exogenous lignite from the Lias to the Lower Devonian, will now venture to say that fossil wood may not yet be detected as low in the scale as any vegetable organism whatever, or fossil fish as low as the remains of any animal? But though the response of the earlier geologic systems be thus unfavorable to the development hypothesis, may not