te beds of limestone, sandstone, and
stratified clay, and which we find represented in Caithness by the
extensively developed flag-stones. And then, the rock disappearing, I
passed over a pebbly beach mottled with boulders; and in a little bay
not half a mile distant from the town, I again found the rock laid bare.

I had long before observed that the rock rose to the surface in this
little bay; I had even employed, when a boy, pieces of its stratified
clay as slate-pencil; but I had yet failed minutely to examine it. I was
now, however, struck by its resemblance, in all save colour, to the
Lias. The strata lay at a low angle: they were composed of an
argillaceous shale, and abounded in limestone nodules; and, save that
both shale and nodules bore, instead of the deep Liassic grey, an
olivaceous tint, I might have almost supposed I had fallen on a
continuation of some of the Eathie beds. I laid open a nodule with a
blow of the hammer, and my heart leaped up when I saw that it enclosed
an organism. A dark, ill-defined, bituminous mass occupied the centre;
but I could distinguish what seemed to be spines and small ichthyic
bones projecting from its edges; and when I subjected them to the
scrutiny of the glass, unlike those mere chance resemblances which
sometimes deceive for a moment the eye, the more distinct and
unequivocal did their forms become. I laid open a second nodule. It
contained a group of glittering rhomboidal scales, with a few cerebral
plates, and a jaw bristling with teeth. A third nodule also supplied its
organism, in a well-defined ichthyolite, covered with minute,
finely-striated scales, and furnished with a sharp spine in the
anterior edge of every fin. I eagerly wrought on, and disinterred, in
the course of a single tide, specimens enough to cover a museum table;
and it was with intense delight that, as the ripple of the advancing
tide was rising against the pebbles, and covering up the ichthyolitic
beds, I carried them to the higher slopes of the beach, and, seated on a
boulder, began carefully to examine them in detail with a common
botanist's microscope. But not a plate, spine, or scale, could I detect
among their organisms, identical with the ichthyic remains of the Lias.
I had got amid the remains of an entirely different and incalculably
more ancient creation. My new-found organisms represented, not the
first, but merely the second age of vertebrate existence on our planet;
but as the remains of