still entire--I trust to be able by and by to present to the public in a good engraving. There occur jaws, plates, scales spines,--the remains of fucoids, too, of great size and in vast abundance. Mr. Dick has disinterred from among the rocks of Sanday Bay flattened carbonaceous stems four inches in diameter. We are still within an hour's walk of Thurso; but in that brief hour how many marvels have we witnessed!--how vast an amount of the vital mechanisms of a perished creation have we not passed over! Our walk has been along ranges of sepulchres, greatly more wonderful than those of Thebes or Petraea, and mayhap a thousand times more ancient. There is no lack of life along the shores of the solitary little bay. The shriek of the sparrow-hawk mingles from the cliffs with the hoarse deep croak of the raven; the cormorant on some wave-encircled ledge, hangs out his dark wing to the breeze; the spotted diver, plying his vocation on the shallows beyond, dives and then appears, and dives and appears again, and we see the silver glitter of scales from his beak; and far away in the offing the sunlight falls on a scull of seagulls, that flutter upwards, downwards, and athwart, now in the air, thick as midges over some forest-brook in an evening of midsummer. But we again pass onwards, amid a wild ruinous scene of abrupt faults, detached fragments of rocks, and reversed strata: again the ledges assume their ordinary position and aspect, and we rise from lower to higher and still higher beds in the formation,--for such, as I have already remarked, is the general arrangement from west to east, along the northern coast of Caithness, of the Old Red Sandstone. The great Conglomerate base of the formation we find largely developed at Port Skerry, just where the western boundary line of the county divides it from the county of Sutherland; its thick upper coping of sandstone we see forming the tall cliffs of Dunnet Head; and the greater part of the space between, nearly twenty miles as the crow flies, is occupied chiefly by the shales, grits, and flagstones, which we have found charged so abundantly with the strangely-organized ichthyolites of the second stage of vertebrate existence. In the twenty intervening miles there are many breaks and faults, and so there may be, of course, recurrences of the same strata, and re-appearances of the same beds; but, after making large allowance for partial foldings and repetitions, we must regard the development of this formation, with which the twenty miles are occupied, as truly enormous. And yet it is but one of three that occur in a single system. We reach the long flat bay of Dunnet, and cross its waste of sands. The incoherent coils of the sand-worm lie thick on the surface; and here a swarm of buzzing flies, disturbed by the foot, rises in a cloud from some tuft of tangled sea-weed; and here myriads of gray crustaceous sand-hoppers dart sidelong in the little