e as its guest, notwithstanding the badness of the
character that, in common honesty, I had to certify as my own. Next
morning I breakfasted at the manse, and was introduced by Mr. Learmonth
to two gentlemen of the place, who had been kindly invited to meet with
me, and who, from their acquaintance with the geology of the district
enabled me to make the best use of my time, by cutting direct on those
cliffs and quarries in the neighborhood in which organic remains had
been detected, instead of wearily re-discovering them for myself. There
is a small but interesting museum in Stromness, rich in the fossils of
the locality; and I began the geologic business of the day by devoting
an hour to the examination of its organisms, chiefly ichthyolites. I saw
among them several good specimens of the genus Pterichthys, and of what
is elsewhere one of the rarer genera of the Dipterians,--the
Diplopterus. A well-marked individual of the latter genus had, I found,
been misnamed Dipterus by some geological visitor who had recently come
the way,--a mistake which, as in both ichthyolites the fins are
similarly placed, occasionally occurs, but which may be easily avoided,
when the specimens are in a tolerable state of preservation, by taking
note of a few well-marked characteristics by which the genera are
distinguished. In both Dipterus and Diplopterus the bright enamel of the
scales was thickly punctulated by microscopic points,--the exterior
terminations of funnel-shaped openings, that communicated between the
surface and the cells of the middle table of the scale; but the form of
the scales themselves was different,--that of the Dipterus being nearly
circular, and that of the Diplopterus, save on the dorsal ridge,
rhomboidal. Again, the lateral line of the Diplopterus was a raised
line, running as a ridge along the scales; whereas that of the Dipterus
was a depressed one, existing as a furrow. Their heads, too, were
covered by an entirely dissimilar arrangement of plates. The rounded
snout-plate of the Diplopterus was suddenly contracted to nearly
one-half its breadth by two semi-circular inflections, which formed the
orbits of the eyes; full in the centre, a little above these, a minute,
lozenge-shaped plate seemed as if inlaid in the larger one, the
analogue, apparently, of the anterior frontal; and over all there
expanded a broad plate, the superior frontal, half divided vertically by
a line drawn downwards from the nape, which, how