layers was ranged
at right angles with the line of the _tear_ in four. There were thus in
a single scale, in order to secure the greatest possible amount of
strength,--and who can say what other purposes may have been secured
besides?--three distinct principles embodied,--the principle of the two
tables and _diploe_ of the human skull,--the principle of the variously
arranged coats of the human stomach,--and the principle of Oliver
Cromwell's "fluted pot." There have been elaborate treatises written on
those ornate flooring-tiles of the classical and middle ages, that are
occasionally dug up by the antiquary amid monastic ruins, or on the
sites of old Roman stations. But did any of them ever tell a story half
so instructive or so strange as that told by the incalculably more
ancient ganoid _tiles_ of the Palaeozoic and Secondary periods?

I called, on my way back from Linksfield, upon my old friend Mr. Patrick
Duff, and was introduced once more to his exquisite collection, with its
unique ichthyolites of at least two genera of fishes of the Old
Red,--the _Stagonolepis_ and _Placothorax_ of Agassiz,--which up to the
present time are to be seen nowhere else; and various other fine
specimens of rare species, which, having sat for their portraits, have
their forms preserved in the great work of the naturalist of Neufchatel.
He showed me, with some triumph, one of his later acquisitions,--a fine
specimen of Holoptychius from the upper yellow sandstone of Bishop-Mill,
which exhibits the dorsal ridge covered with a line of large overlapping
scales, not at all unlike those overlapping plates which cover the tail
of the lobster; for which, by the way, they were mistaken by the workman
who first laid the fossil open. I examined, too, with some interest,
fragments of a gigantic species of Pterichthys, belonging to an inferior
division of the same Upper Old Red formation as the yellow stone,
designated by Agassiz _Pterichthys major_, which must have attained to
at least thrice the size, linearly, of even its bulkier congeners of the
Lower formation of the Coccosteus. After examining many a drawer,
stored, from the deposits of the neighborhood, with characteristic
fossils of the Lias, the Weald, and the Oolite, and of the Upper and
Lower Old Red, we set out together to expatiate amid the treasures of
the Town Museum.

Among other recent additions to the Museum, there is an interesting set
of the fishes of the Ganges, the donation