Origin of Species Variorum

Comparison with 1866

and it cannot on my theory be supposed, that these old species were the progenitors of all the species belonging to the same group which have subsequently appeared, for they do not present characters in any degree intermediate between them. ↑

Consequently, if my theory be true, it is indisputable that, before the lowest Silurian stratum was deposited, long periods elapsed, as long as, or probably far longer than, the whole interval from the Silurian age to the present day; and that during these vast, yet quite unknown, periods of time, the world swarmed with living creatures. ↑ ↑

To the question why we do not find richly fossiliferous records of these vast primordial periods, I can give no satisfactory answer. Several ... eminent geologists, with Sir R. Murchison at their head, were until recently convinced that we beheld in the organic remains of the lowest Silurian stratum the first dawn of life on this planet. Other highly competent judges, as Lyell and the late E. Forbes , disputed this conclusion. We should not forget that only a small portion of the world is known with accuracy. M. Barrande not long ago added another and lower stage to the Silurian system, abounding with new and peculiar species. Remnants of several forms have been detected in the Longmynd beds beneath Barrande's so-called primordial zone. ↑ The presence also of phosphatic nodules and bituminous matter in some of the lowest azoic rocks, probably indicates the former existence of life at these periods. But now within the last year the great discovery of the Eozoon in the Laurentian formation of Canada has been made; and after reading Dr. Carpenter's description of this remarkable fossil, it is impossible to feel any doubt regarding its organic nature. There are three great series of strata beneath the Silurian system in Canada, in the lowest of which the Eozoon was found; and Sir W. Logan states that their "united thickness may possibly far surpass that of all the succeeding rocks, from the base of the palæozoic series to the present time. We are thus carried back to a period so far remote, that the appearance of the so-called Primordial fauna (of Barrande) may by some be considered a comparatively modern event." The Eozoon belongs to the most lowly organised of all classes of animals, but for its class is highly organised; it existed in countless numbers, and, as Dr. Dawson has remarked, certainly preyed on other minute organic beings, which must have lived in great numbers. There is also reason to believe that at this enormously remote period plants of some kind existed. Thus the words above given, which I wrote in 1859, and which are almost the same with those used by Sir W. Logan, have come true. Notwithstanding these several facts, the difficulty of assigning any good cause for the absence beneath the Silurian formations of vast piles of strata rich in fossils is very great. If the

and it cannot on my theory be supposed, that these old species were the progenitors of all the species of the orders to which they belong, for they do not present characters in any degree intermediate between them. If, moreover, they had been the progenitors of these orders, they would almost certainly have been long ago supplanted and exterminated by their numerous and improved descendants.

Consequently, if my theory be true, it is indisputable that before the lowest Silurian stratum was deposited, long periods elapsed, as long as, or probably far longer than, the whole interval from the Silurian age to the present day; and that during these vast, yet quite unknown, periods of time, the world swarmed with living creatures. ↑ ↑

To the question why we do not find records of these vast primordial periods, I can give no satisfactory answer. Several of the most eminent geologists, with Sir R. Murchison at their head, are convinced that we see in the organic remains of the lowest Silurian stratum the dawn of life on this planet. Other highly competent judges, as Lyell and the late E. Forbes , dispute this conclusion. We should not forget that only a small portion of the world is known with accuracy. M. Barrande has lately added another and lower stage to the Silurian system, abounding with new and peculiar species. Traces of life have been detected in the Longmynd beds, beneath Barrande's so-called primordial zone. The presence of phosphatic nodules and bituminous matter in some of the lowest azoic rocks, probably indicates the former existence of life at these periods. But the difficulty of understanding the absence of vast piles of fossiliferous strata, which on my theory no doubt were somewhere accumulated before the Silurian epoch, is very great. If these