or, though, after I left Cromarty for Edinburgh, it was often
explored by geologic tourists, and by a few cultivators of science in
the place, was it wholly exhausted for ten years more. The ganoids of
the second age of vertebrate existence must have congregated as thickly
upon that spot in the times of the Lower Old Red Sandstone, as herrings
ever do now, in their season, on the best fishing-banks of Caithness or
the Moray Firth. I was for some time greatly puzzled in my attempts to
restore these ancient fishes, by the peculiarities of their
organization. It was in vain I examined every species of fish caught by
the fishermen of the place, from the dog-fish and the skate to the
herring and the mackerel. I could find in our recent fishes no such
scales of enamelled bone as those which had covered the _Dipterians_ and
the _Celacanths_; and no such plate-encased animals as the various
species of _Coccosteus_ or _Pterichthys_. On the other hand, with the
exception of a double line of vertebral processes in the _Coccosteus_, I
could find in the ancient fishes no internal skeleton: they had
apparently worn all their bones outside, where the crustaceans wear
their shells, and were furnished inside with but frameworks of
perishable cartilage. It seemed somewhat strange, too, that the
geologists who occasionally came my way--some of them men of
eminence--seemed to know even less about my Old Red fishes and their
peculiarities of structure, than I did myself. I had represented the
various species of the deposit simply by numerals, which not a few of
the specimens of my collection still retain on their faded labels; and
waited on until some one should come the way learned enough to
substitute for my provisional figures words by which to designate them;
but the necessary learning seemed wanting, and I at length came to find
that I had got into a _terra incognita_ in the geological field, the
greater portion of whose organisms were still unconnected with human
language. They had no representatives among the vocables.

I formed my first imperfect acquaintance with the recent ganoidal fishes
in 1836, from a perusal of the late Dr. Hibbert's paper on the deposit
of Burdiehouse, which I owed to the kindness of Mr. George Anderson. Dr.
Hibbert, in illustrating the fishes of the Coal Measures, figured and
briefly described the Lepidosteus of the American rivers as a still
surviving fish of the early type; but his description of the animal