retain their
thickness, though existing as fragments several feet in length, with but
little diminution throughout. They resembled the interior casts of
Calamites in being longitudinally furrowed; but the furrows are flatter,
and are themselves minutely striated lengthwise by lines as fine as
hairs; and, instead of presenting any appearance of joints, there run
diagonally across the stems, interrupted and very irregular lines of
knobs. These I find referred to by Dr. Joseph Hooker, in describing a
set of massive but ill preserved remains of the same organism detected
in South Ness quarry, near Lerwick, by the Hon. Mr. Tuffnell, as taking,
in two of the specimens, "the appearance of transverse knobs and bars
(mayhap spirally arranged) that cross the striae obliquely. But though
the knobs," he adds, "may perhaps indicate a peculiar character of the
plants, they have more probably been caused by pressure during
silicification." As, however, they also occur in the best preserved
fragment of the plant which I have yet seen,--a Thurso specimen which I
owe to my friend Mr. Dick,--I deem it best to regard them, provisionally
at least, as one of the characteristics of the plant. I may mention,
that while I disinterred one of my specimens from the Thurso flagstones,
where it occurred among remains of Dipterus and Asterolepis, I derived
another specimen from the great overlying formation of pale Red
Sandstone to which the lofty hills of Hoy and the tall mural precipices
of Dunnet Head belong; and that this plant is the only organism which
has yet been found in this uppermost member of the Lower Old Red, to at
least the north of the Moray Firth. Another apparently terrestrial
organism of the lower formation, of, however, rare occurrence, very much
resembles a sheathing bract or spathe. It is of considerable size,--from
four to six inches in length, by from two to three inches in
breadth,--of a broadly elliptical and yet somewhat lanceolate form,
deeply but irregularly corrugated, the rugae exhibiting a tendency to
converge towards both its lower and upper terminations, and with, in
some instances, what seems to be the fragment of a second spathe
springing from its base. Another and much smaller vegetable organism of
the same beds presents the form of a spathe-enveloped bud or unblown
flower wrapped up in its calyx; but all the specimens which I have yet
seen are too obscure to admit of certain determination. I may here
mention, tha