suppose that when the excavation has been carried a hundred yards into the cemetery, a geologist, finding the laborers cutting on the average about a yard per day, simply intimates as his opinion that the laborers have been a hundred days at work. "No," replies a controversialist on the anti-geological side; "for the first fifty yards, so soft was the subsoil, and so shallow the covering of mould, that the laborers must have cut at the rate of two yards a day; it has been merely for the last fifty yards that they have been excavating at the present slow rate: they cannot have been more than seventy-five days at work. I marvel exceedingly at the absurdity of geological reasoners: palpably the burying-ground of the Calton is only seventy-five days old." Now, such, in no exaggerated, but, on the contrary, greatly modified form, is the argument that would limit the age of the earth to the period during which the St. Lawrence has been scooping out a channel for itself, from Queenston to Niagara, through an ancient Silurian burying-ground. Both arguments alike confound the age of the ancient burying-grounds with the date of the modern excavations opened up through them; but in order to render the argument of my illustration equally absurd with the other, it would be not only necessary to infer that the Calton cemetery was only seventy-five days old, but also that the rock on which it rested was no older.

But enough of follies such as these! I had marked a good many other passages of similar character in the writings of the recent anti-geologists, and would have little difficulty in filling a volume with such; but it would be a useless, though mayhap curious work, and is much better exhibited by specimen than as a whole. A little folly is amusing, but much of it fatigues. There is a time coming, and now not very distant, when the vagaries of the antigeologists will be as obsolete as those of the geographers of

at

Salamanca, or as those of the astronomers who upheld the orthodoxy of Ptolemy against Galileo and Newton; and when they will be regarded as a sort of curious fossils, very monstrous and bizarre, and altogether of an extinct type, but which had once not only life, but were formidable. It will then be seen by all what a noble vestibule the old geologic ages form to that human period in which moral responsibility first began upon earth, and a creature destined to immortality anticipated an eternal hereafter. There is always much of the mean and the little in the worlds which man creates for himself, and in the history which he gives them. Of all the abortions of the middle ages which have come down to us, I know not a more miserable one, once ludicrous and sad, than that heavens and earth of Cosmas Indicopleustes, the monk, which I illustrated by diagrams in my last lecture (Figs. 114, 115). They are just such heavens and earth as a monk might have made, and made too at a sitting. The heavens, represented as a solid arch raised on tall walls, resemble, as a whole, the arch which figures in the middle of a freemason's apron, or, more homely still, the section of a wine cellar; while the earth lies beneath as a great plain or floor, with a huge hill in the distance, behind which the sun passes when it is night. And yet this scheme gave law to the world for more than six centuries, and lay like a nightmare on physical discovery, astronomic and geographical. The anti-geologists have been less mischievous, for they live in a more enlightened age; and we already see but the straggling remains of the body, and know that the time cannot be far distant when it will be as completely extinct as any of the old faunas. The great globe, ever revolving on itself, and journeying in space round the sun, in obedience to laws which it immortalized a Newton to discover and demonstrate, is an infinitely more sublime and noble object than

the earth of Cosmas the monk, with its conical mountain and its crypt-like firmament; nor can I doubt that its history throughout the long geologic ages, its strange story of successive creations, each placed in advance of that which had gone before, and its succeeding organisms, vegetable and animal, ranged according to their appearance in time, on principles which our profounder students of natural science have but of late determined, — will be found in an equal degree more worthy of its Divine Author than that which would huddle the whole into a few literal days, and convert the incalculably ancient universe which we inhabit into a hastily run-up erection of yesterday.

LECTURE ELEVENTH.

ON THE LESS KNOWN FOSSIL FLORAS OF SCOTLAND.*

PART I.

SCOTLAND has its four fossil floras, its flora of the Old Red Sandstone, its Carboniferous flora, its Oolitic flora, and that flora of apparently Tertiary age of which his Grace the Duke of Argyll found so interesting a fragment overflown by the thick basalt beds and trap tuffs of Mull. Of these, the only one adequately known to the geologist is the gorgeous flora of the Coal Measures, probably the richest, in at least individual plants, which the world has yet seen. The others are all but wholly unknown; and the Association may be the more disposed to tolerate the comparative meagreness of the few brief remarks which I purpose making on two of their number, the floras of the Old Red Sandstone and the Oolite, from the consideration that that meagreness is only too truly representative of the present state of our knowledge regarding them; and that if my descriptions be scanty and inadequate, it is only because the facts are still few. How much of the lost may

* The substance of this and the following lecture was originally given in a single paper, before the Geological Section of the British Association, held at Glasgow in September 1855. So considerable have been the additions, however, that the one paper has swelled into two lectures. Most of the added matter was at first thrown into the form of Notes; but it was found, that from their length and frequency, they would have embarrassed the printer, mayhap the reader also; and so most of the larger ones have been introduced into the text within brackets.

yet be recovered I know not; but the circumstance that two great floras, remote predecessors of the existing one, which once covered with their continuous mantle of green the dry land of what is now Scotland, should be represented by but a few coniferous fossils, a few cycadaceous fronds, a few ferns and club mosses, must serve to show what mere fragments of the past history of our country we have yet been able to recover from the rocks, and how very much in the work of exploration and discovery still remains for us to do. We stand on the further edge of the great floras of by-past creations, and have gathered but a few handfuls of faded leaves, a few broken branches, a few decayed cones.

The Silurian deposits of our country have not yet furnished us with any unequivocal traces of a terrestrial vegetation. Professor Nicol of Aberdeen, on subjecting to the microscope the ashes of a Silurian anthracite which occurs in Peeblesshire, detected in it minute tubular fibres, which seem, he says, to indicate a higher class of vegetation than the algæ; but these may have belonged to a marine vegetation notwithstanding. I detected some years ago, in the Trilobite-bearing schists of Girvan, associated with graptolites of the Lower Silurian type, a vegetable organism somewhat resembling the leaf of one of the pond weeds,an order of plants, some of whose species, such as Zostera, find their proper habitats in salt water. I have placed beside this specimen a fragment of the same graptolitebearing rock, across which I have pasted part of a leaf of Zostera marina, the only plant of our Scottish seas which is furnished with true roots, bears real flowers inclosed in herbaceous spathes, and produces a well formed farinaceous seed. It will be seen, that in the few points of comparison which can be instituted between forms so exceedingly simple, the ancient very closely resembles the recent organism.