eable; and farther on still, where the steep wall of
cliffs sinks into a line of grassy banks, I saw in yet another quarry,
ichthyolites of all the three great ganoid families so characteristic of
the Old Red,--Cephalaspians, Dipterians, and Acanthodians,--ranged in
the three-storied order to which I have already referred as so
inexplicable. The specimens, however, though numerous, are not fine.
They are resolved into a brittle bituminous coal, resembling hard pitch
or black wax, which is always considerably less tenacious than the
matrix in which they are inclosed; and so, when laid open by the hammer,
they usually split through the middle of the plates and scales, instead
of parting from the stone at their surfaces, and resemble, in
consequence, those dark, shadow-like profiles taken in Indian ink by the
limner, which exhibit a correct outline, but no details. We find,
however, in some of the genera, portions of the animal preserved that
are rarely seen in a state of keeping equally perfect in the
ichthyolites of Cromarty, Moray, or Banff,--those terminal bones of the
Coccosteos, for instance, that were prolonged beyond the plates by which
the head and upper parts of the body were covered. Wherever the
ichthyolites are inclosed in nodules, as in the more southerly counties
over which the deposit extends, the nodule terminates, in almost every
case, with the massier portions of the organism; for the thinner parts,
too inconsiderable to have served as attractive nuclei to the stony
matter when the concretion was forming, were left outside its pale, and
so have been lost; whereas, in the northern districts of the deposit,
where the fossils, as in Caithness and Orkney, occur in flagstone, these
slimmer parts, when the general state of keeping is tolerably good, lie
spread out on the planes of the slabs, entire often in their minutest
rays and articulations. The numerous Coccostei of this quarry exhibit,
attached to their upper plates, their long vertebral columns, of many
joints, that, depending from the broad dorsal shields of the
ichthyolite, remind one of those skeleton fishes one sometimes sees on
the shores of a fishing village, in which the bared backbone joints on,
cord-like, to the broad plates of the skull. None of the other fishes of
the Old Red Sandstone possessed an internal skeleton so decidedly
osseous as that of the Coccosteus, and none of them presented externally
so large an extent of naked skin,--provision