few of his rarer specimens. One of the number,--a
minute ichthyolite, about three inches in length,--I was at first
disposed to set down as new, but I have since come to regard it as
simply an imperfectly-preserved specimen of a Cromarty and Morayshire
species,--the _Glyptolepis microlepidotus_; though its state of keeping
is such as to render either conclusion an uncertainty. Another of the
specimens was that of a fish, still comparatively rare, first figured in
the first edition of my little volume on the "Old Red Sandstone," from
the earliest found specimen, at a time while it was yet unfurnished with
a name, but which has since had a place assigned to it in the genus
Diplacanthus, as the species longispinus. The scales, when examined by
the glass, remind one, from their pectinated character, of shells
covering the walls of a grotto,--a peculiarity to which, when showing my
specimen to Agassiz, while it had yet no duplicate, I directed his
attention, and which led him to extemporize for it, on the spot, the
generic name Ostralepis, or shell-scale. On studying it more leisurely,
however, in the process of assigning to it a place in his great work,
where the reader may now find it figured (Table XIV., fig. 8), the
naturalist found reason to rank it among the Diplacanthi. Mr. Watt's
specimen exhibited the outline of the head more completely than mine;
but the Orkney ichthyolites rarely present the microscopic minutiae; and
the shell-like aspect of the scales was shown in but one little patch,
where they had left their impressions on the stone. His other specimens
consisted of single plates of a variety of Coccosteus, undistinguishable
in their form and proportions from those of the _Coccosteus decipiens_,
but which exceeded by about one-third the average size of the
corresponding parts in that species; and of a rib-like bone, that
belonged apparently to what few of the ichthyolites of the Lower Old Red
seem to have possessed,--an osseous internal skeleton. This last
organism was the only one I saw in Orkney with which I had not been
previously acquainted, or which I could regard as new, though possibly
enough it may have formed part, not of an undiscovered genus, but of the
known genus Asterolepis, of whose inner framework, judging from the
Russian specimens at least, portions must have been bony. After parting
from Mr. Watt, I travelled on to Kirkwall, which, after a leisurely
journey, I reached late in the evening, and