although he always wrote doubtfully on the subject, has now been ascertained to be, not Old Red, but Silurian. In Sir Roderick's last Address to the British Association, he says, Professor Sedgwick and himself had thirty-one years ago ascertained an ascending order from gneiss, covered by quartz rocks, with limestone, into overlying quartzose, micaceous, and other crystalline rocks, some of which have a gneissose character. They had also observed what they supposed to be an associated formation of red grit and sandstone; but the exact relations of this to the crystalline rocks was not ascertained, owing to bad weather. In the meantime, they, as well as all subsequent geologists, had erred in believing the great and lofty masses of purple and red conglomerate of the western coast were of the same age as those on the east, and therefore 'Old Red Sandstone.' . . . 'Professor Nicol had suggested that the quartzites and limestones might be the equivalent of the Carboniferous system of the south of Scotland. Wholly dissenting from that hypothesis, he (Sir Roderick) had urged Mr. Peach to avail himself of his first leisure moments to re-examine the fossil-beds of Durness and Assynt, and the result was the discovery of so many forms of undoubted Lower Silurian characters (determined by Mr. Salter), that the question has been completely set at rest, there being now no less than nineteen or twenty species of M'Lurea, Murchisonia, Cephalita, and Orthoceras, with an Orthis, etc., of which ten or eleven occur in the Lower Silurian rocks of North America.' This change would demand an entirely new map of the Geology of Scotland; for there is clearly ascertained to be an ascending series from west to east, beginning with an older or primitive gneiss, on which a Cambrian conglomerate, and over that again a band containing the Silurian fossils, rest; while a younger gneiss occupies a portion of the central nucleus, having the Old Red Sandstone series on the eastern side. A change has likewise been made in the internal arrangements of the Old Red, of which the next edition of my husband's work on the subject will be the proper place to speak in detail. In the meantime, I may just mention, that the Caithness and Cromarty beds have been found to occupy, not the lowest, but the central place, the lowest being assigned to the Forfarshire beds, containing Cephalaspis, associated with Pteraspis, an organism characteristically Silurian. That which bears most upon the subject before us is the now perfectly ascertained imprint of the footsteps of large reptiles in the Elgin or uppermost formation of the Old Red. A shade of doubt had rested upon the discovery made many years ago by Mr. Patrick Duff of the Telerpeton Elginense, not as to the real nature of the fossil, which is indisputably a small lizard, but as to whether the stratum in which it was found belonged to the Old Red, or to the formation immediately above it. It will be observed, however, that the existence of reptiles in the Old Red did not rest altogether upon this, because the footprints of large animals of the same class had been ascertained in the United States of America. I cannot but conceive, therefore, that Mr. Duff, in a recent letter or paper read in Elgin, and published in the Elgin and Morayshire Courier, makes too much of the recent discoveries in his neighbourhood, when he asserts that the Old Red Sandstone has been hitherto considered exclusively a fish formation, and that the appearance of reptiles is altogether novel. 'Now,' says he, that the Old Red Sandstones of Moray have acquired some celebrity, it may not be unprofitable to trace the different stages by which the discovery was arrived at of reptilian remains in that very ancient system, which till now was held to have been peopled by no higher order of beings than fishes.' Mr. Duff forgets that in the programme, as it may be called, given by my husband, of the introduction of different types of animal life, as ascertained in his day, reptiles are made to occupy precisely the position they do now. To refresh the memory of the reader, I shall here reproduce it, as given in the Testimony of the Rocks. At page 14 is this diagram: Geologic [Rad. Art. Mol. Fish. Rep. Bird. Mam. Man.] arrangement. -'In And immediately following it occurs this comment :-" the many-folded pages of the Old Red Sandstone, till we reach the highest and last, there occur the remains of no other vertebrates than those of this fourth class [fishes]; but in its uppermost deposits there appear traces of the third or reptilian class; and in passing upwards still, through the Carboniferous, Permian, and Triassic systems, we find reptiles continuing the master-existences of the time.' At pages 16, 17, express allusion is made to the Telerpeton Elginense, with the doubt as to the nature of its locale very slightly touched upon.1 All this Mr. Duff has forgotten, apparently; and it appears likewise not to have come within his cognizance that Sir Charles Lyell distinctly recognises his Telerpeton as well as the American footprints, and assigns both their proper places, in the last edition of his Principles. Even in the edition before the last of the Siluria, almost the first thing that meets us, on opening it at Chapter Tenth, which treats of the Old Red Sandstone, is a print of the fossil skeleton of this same Telerpeton Elginense, its true place assigned to it with quite as much certainty as now! These very singlar lapses in memory seem not to be peculiar to Mr. Duff. I have seen it stated in an anonymous article published in a widely circulated journal,1 and in connexion with the discovery of the Elgin reptile foot-prints, that Hugh Miller considered the Old Red Sand 1 This doubt, I see by Sir Roderick Murchison's latest Address to the British Association, is not yet entirely obviated. See Appendix. 2 For this article, as an excellent specimen of its class, see Appendix, under the head ‘Recent Geological Discoveries;' and, in contradistinction to it, the extract from Sir R. Murchison's Address ought to be carefully studied. I myself had seen neither that extract nor the recent Siluria until after this short sketch was in type; the references to the latter having been introduced afterwards; and it may be conceived with what feelings of gratification I have perused Sir Roderick's repeated assurances of adherence to the 'Old Light.' stone to have been a shoreless ocean without a tree !— utterly ignoring the fact that he was himself the discoverer of the first Old Red fossil-wood of a coniferous character, and that he thence expressly infers the then existence of vegetation of a high order. Is it not enough to add to the store of knowledge without attempting to undermine all that has gone before? Must the discovery of an additional reptile, a few additional marsupials, be the signal for the immediate outcry, 'All is changed; the former things have passed away; all things have become new'? My husband was solicitous even to the point of nervous anxiety to exclude from his writings every particle of error, whether of facts or of the conclusions to be drawn from them. Much rather would he never have written at all than feel himself in any degree a false teacher. 'Truth first, come what may afterwards,' was his invariable motto. In the same spirit, God enabling me, I have been desirous to carry on the publication of his posthumous writings. God forbid that one intrusted with such sacred guardianship should seek to pervert or suppress a single truth, actual or presumptive, even though its evidence were to overthrow in a single hour all his much-loved speculations,-all his reasonings, so long cogitated, so conscientiously wrought out. Yet I must confess that I was at first startled and alarmed by rumours of changes and discoveries which, I was told, were to overturn at once the science of Geology as hitherto received, and all the evidences which had been drawn from it in favour of revealed religion. Though well persuaded that at all times, and by the most unexpected methods, the Most High is able to assert Himself, the proneness of man to make use of every unoccupied position in order to maintain |