ich plates of the buckler
species were at first mistaken for those of a Chelonian, as are
exhibited by plates of the larger kinds, with an area ten times as
great; its tubercles, too, some of them of microscopic size, are as
numerous;--evidences, I think,--when we take into account that in the
bulkier species the lines and tubercles increased in number with the
growth of the plates, and that, once formed, they seem never to have
been affected by the subsequent enlargement of the creature,--that this
ichthyolite was not an _immature_, but really a _miniature_ Coccosteus.
We may see on the plates of the full-grown Coccosteus, as on the shells
of bivalves, such as _Cardium echinatum_, or on those of spiral
univalves, such as _Buccinum undatum_, the diminutive markings which
they bore when the creature was young; and on the plates of this species
we may detect a regular gradation of tubercles from the microscopic to
the minute, as we may see on the plates of the larger kinds a regular
gradation from the minute to the fall-sized. The average length of the
dwarf Coccosteus of Thurso and Kirkwall, taken from the snout to the
pointed termination of the dorsal plate, ranges from one and a-half to
two inches; its entire length from head to tail probably from three to
four. It was from one of Mr. Dick's specimens of this species that I
first determined the true position of the eyes of the Coccosteus,--a
position which some of my lately-found ichthyolites conclusively
demonstrate, and which Agassiz, in his restoration, deceived by
ill-preserved specimens, has fixed at a point considerably more lateral
and posterior, and where eyes would have been of greatly less use to the
animal. About a field's breadth below this quarry of the _Coccosteus
minor_,--if I may take the liberty of extemporizing a name, until such
time as some person better qualified furnishes the creature with a more
characteristic one,--there are the remains, consisting of fosse and
rampart, with a single cannon lying red and honeycombed amid the ruins,
of one of Cromwell's forts, built to protect the town against the
assaults of an enemy from the sea. In the few and stormy years during
which this ablest of British governors ruled over Scotland, he seems to
have exercised a singularly vigilant eye. The claims on his protection
of even the remote Kirkwall did not escape him.

The antiquities of the burgh next engaged me; and, as became its dignity
and importance, I be