Fossils of the Upper Old Red Sandstone much more imperfectly
preserved than those of the Lower.--The Causes obvious.--Difference
between the two Groups, which first strikes the Observer, a
Difference in Size.--The _Holoptychius_ a characteristic Ichthyolite
of the Formation.--Description of its huge Scales.--Of its Occipital
Bones, Fins, Teeth, and General Appearance.--Contemporaries of the
_Holoptychius_.--Sponge-like Bodies.--Plates resembling those of
the Sturgeon.--Teeth of various Forms, but all evidently the Teeth
of Fishes.--Limestone Band, and its probable Origin.--Fossils of
the Yellow Sandstone.--The _Pterichthys_ of Dura Den.--Member of
a Family peculiarly characteristic of the System.--No intervening
Formation between the Old Red Sandstone and the Coal Measures.--The
_Holoptychius_ contemporary for a time with the _Megalichthys_.--The
Columns of Tubal Cain.
The different degrees of entireness in which the geologist finds his
organic remains, depend much less on their age than on the nature
of the rock in which they occur; and as the arenaceous matrices of
the Upper and Middle Old Red Sandstones have been less favorable
to the preservation of their peculiar fossils than the calcareous
and aluminous matrices of the Lower, we frequently find the older
organisms of the system fresh and unbroken, and the more modern
existing as mere fragments. A fish thrown into a heap of salt would
be found entire after the lapse of many years; a fish thrown into
a heap of sand would disappear in a mass of putrefaction in a few
weeks; and only the less destructible parts, such as the teeth,
the harder bones, and perhaps a few of the scales, would survive.
Now, limestone, if I may so speak, is the preserving salt of the
geological world; and the conservative qualities of the shales and
stratified clays of the Lower Old Red Sandstone are not much inferior
to those of lime itself; while, in the Upper Old Red, we have merely
beds of consolidated sand, and these, in most instances, rendered
less conservative of organic remains than even the common sand of our
shores, by a mixture of the red oxide of iron. The older fossils,
therefore, like the mummies of Egypt, can be described well nigh as
minutely as the existences of the present creation; the newer, like
the comparatively modern remains of our churchyards, exist, except
in a few rare cases, as mere fragments, and demand powers such as
those of a Cuvier or an Agassiz to restore them to their original
combinations. But cases, though few and rare, do occur in which,
through some favorable accident connected with the death or sepulture
of some individual existence of the period, its remains have been
preserved almost entire; and one such specimen serves to throw light
on whole heaps of the broken remains of its contemporaries. The
single elephant, preserved in an iceberg beside the Arctic Ocean,
illustrated the peculiarities of the numerous extinct family to which
it belonged, whose bones and huge tusks whiten the wastes of Siberia.
The human body found in an Irish bog, with the ancient sandals of
the country still attached to its feet by thongs, and clothed in a
garment of coarse hair, gave evidence that bore generally on the
degree of civilization attained by the inhabitants of an entire
district in a remote age. In all such instances, the character
and appearance of the individual bear on those of the tribe. In
attempting to describe the organisms of the Lower Old Red Sandstone,
where the fossils lie as thickly in some localities as herrings on
our coasts in the fishing season, I felt as if I had whole tribes
before me. In describing the fossils of the Upper Old Red Sandstone,
I shall have to draw mostly from single specimens. But the evidence
may be equally sound so far as it goes.
The difference between the superior and inferior groups of the system
which first strikes an observer, is a difference in the size of
the fossils of which these groups are composed. The characteristic
organisms of the Upper Old Red Sandstone are of much greater bulk
than those of the Lower, which seem to have been characterized by a
mediocrity of size throughout the entire extent of the formation.
The largest ichthyolites of the group do not seem to have much
exceeded two feet or two feet and a half in length; its smaller
average from an inch to three inches. A jaw in the possession of Dr.
Traill--that of an Orkney species of _Platygnathus_, and by much
the largest in his collection--does not exceed in bulk the jaw of
a full-grown coal-fish or cod; his largest _Coccosteus_ must have
been a considerably smaller fish than an ordinary-sized turbot; the
largest ichthyolite found by the writer was a _Diplopterus_, of,
however, smaller dimensions than the ichthyolite to which the jaw
in the possession of Dr. Traill must have belonged; the remains of
another _Diplopterus_ from Gamrie, the most massy yet discovered
in that locality, seem to have composed the upper parts of an
individual about two feet and a half in length. The fish, in short,
of the lower ocean of the Old Red Sandstone--and I can speak of it
throughout an area which comprises Orkney and Inverness, Cromarty,
and Gamrie, and which must have included about ten thousand square
miles--ranged in size between the stickleback and the cod; whereas
some of the fish of its upper ocean were covered by scales as large
as oyster-shells, and armed with teeth that rivalled in bulk those
of the crocodile. They must have been fish on an immensely larger
scale than those with which the system began. There have been scales
of the _Holoptychius_ found in Clashbennie which measure three inches
in length by two and a half in breadth, and a full eighth part of
an inch in thickness. There occur occipital plates of fishes in
the same formation in Moray, a full foot in length by half a foot
in breadth. The fragment of a tooth still attached to a piece of
the jaw, found in the sandstone cliffs that overhang the Findhorn,
measures an inch in diameter at the base. A second tooth of the same
formation, of a still larger size, disinterred by Mr. Patrick Duff
from out the conglomerates of the _Scat-Craig_, near Elgin, and now
in his possession, measures two inches in length by rather more than
an inch in diameter. (See Plate X., fig. 4.) There occasionally turn
up in the sandstones of Perthshire ichthyodorulites that in bulk
and appearance resemble the teeth of a harrow rounded at the edges
by a few months' wear, and which must have been attached to fins
not inferior in general bulk to the dorsal fin of an ordinary-sized
porpoise. In short, the remains of a Patagonian burying-ground would
scarcely contrast more strongly with the remains of that battle-field
described by Addison, in which the pygmies were annihilated by the
cranes, than the organisms of the upper formation of the Old Red
Sandstone contrast with those of the lower.[AO]
[Footnote AO: I have permitted this paragraph to remain as originally
written, though the comparatively recent discovery of a gigantic
_Holoptychius_ (_?_) in the Lower Old Red Sandstone of Thurso, by Mr.
Robert Dick of that place, (see introductory note,) bears shrewdly
against its general line of statement. But it will, at least, serve
to show how large an amount of negative evidence may be dissipated
by a single positive fact, and to inculcate on the geologist the
necessity of cautious induction. An individual _Holoptychius_ of
Thurso must have been at least thrice the size of the _Holoptychius_
of the Upper Old Red formation, as exhibited in the specimen of Mr.
Noble, of St. Madoes.]
[Illustration: _PLATE X._]
Of this upper formation the most characteristic and most abundant
ichthyolite, as has been already said, is the _Holoptychius_. The
large scales and plates, and the huge teeth, belong to this genus.
It was first introduced to the notice of geologists in a paper read
before the Wernerian Society in May, 1830, by Professor Fleming, and
published by him in the February of the following year, in _Cheek's
Edinburgh Journal_. Only detached scales and the fragment of a tooth
had as yet been found; and these he minutely described as such,
without venturing to hazard a conjecture regarding the character or
family of the animal to which they had belonged. They were submitted
some years after to Agassiz, by whom they were referred, though not
without considerable hesitation, to the genus _Gyrolepis_; and the
doubts of both naturalists serve to show how very uncertain a guide
mere analogy proves to even men of the first order, when brought to
bear on organisms of so strange a type as the ichthyolites of the
Old Red Sandstone. At this stage, however, an almost entire specimen
of the creature was discovered in the sandstones of Clashbennie, by
the Rev. James Noble, of St. Madoes, a gentleman who, by devoting
his leisure hours to Geology, has extended the knowledge of this
upper formation, and whose name has been attached by Agassiz
to its characteristic fossil, now designated the _Holoptychius
nobilissimus_. His specimen at once decided that the creature had
been no _Gyrolepis_, but the representative of a new genus not less
strangely organized, and quite as unlike the existences of the
present times as any existence of all the past. So marked are the
peculiarities of the _Holoptychius_, that they strike the commonest
observer.
The scales are very characteristic. They are massy elliptical plates,
scarcely less bulky in proportion to their extent of surface than
our smaller copper coin, composed internally of bone, and externally
of enamel, and presenting on the one side a porous structure, and on
the other, when well preserved, a bright, glossy surface. The upper,
or glossy side, is the more characteristic of the two. I have placed
one of them before me. Imagine an elliptical ivory counter, an inch
and a half in length by an inch in breadth, and nearly an eighth part
of an inch in thickness, the larger diameter forming a line which,
if extended, would pass longitudinally from head to tail through the
animal which the scale covered. On the upper or anterior margin of
this elliptical counter, imagine a smooth selvedge or border three
eighth parts of an inch in breadth. Beneath this border there is an
inner border of detached tubercles, and beneath the tubercles large
undulating furrows, which stretch longitudinally towards the lower
end of the ellipsis. Some of these waved furrows run unbroken and
separate to the bottom, some merge into their neighboring furrows at
acute angles, some branch out and again unite, like streams which
enclose islands, and some break into chains of detached tubercles.
(See Plate X., fig. 3.) No two scales exactly resemble one another
in the minuter peculiarities of their sculpture, if I may so speak,
just as no two pieces of lake or sea may be roughened after exactly
the same pattern during a gale; and yet in general appearance
they are all wonderfully alike. Their _style_ of sculpture is the
same--a style which has sometimes reminded me of the Runic knots
of our ancient north country obelisks. Such was the scale of the
creature. The head, which was small, compared with the size of
the body, was covered with bony plates, roughened after a pattern
somewhat different from that of the scales, being tubercled rather
than ridged; but the tubercles present a confluent appearance, just
as chains of hills may be described as confluent, the base of one
hill running into the base of another. The operculum seems to have
been covered by one entire plate--a peculiarity observable, as has
been remarked, among some of the ichthyolites of the Lower Old Red
Sandstone, such as the _Diplopterus_, _Dipterus_, and _Osteolepis_.
And it, too, has its fields of tubercles, and its smooth marginal
selvedge, or border, on which the lower edges of the upper occipital
plates seem to have rested, just as, in the roof of a slated
building, part of the lower tier of slates is overtopped and covered
by the tier above. The scales towards the tail suddenly diminish
at the ventral fins to about one fourth the size of those on the
upper part of the body; the fins themselves are covered at their
bases, which seem to have been thick and fleshy like the base of the
pectoral fin in the cod or haddock, with scales still more minute;
and from the scaly base the rays diverge like the radii of a circle,
and terminate in a semicircular outline. The ventrals are placed
nearer the tail, says Agassiz, than in any other ganoid fish. (See
Plate X., fig. 2.)
But no such description can communicate an adequate conception
to the reader of the strikingly picturesque appearance of the
_Holoptychius_, as shown in Mr. Noble's splendid specimen. There is
a general massiveness about the separate portions of the creature,
that imparts ideas of the gigantic, independently of its bulk as
a whole; just as a building of moderate size, when composed of
very ponderous stones, has a more imposing effect than much larger
buildings in which the stones are smaller. The body measures a foot
across, by two feet and a half in length, exclusive of the tail,
which is wanting; but the armor in which it is cased might have
served a crocodile or alligator of five times the size. It lies on
its back, on a mass of red sandstone; and the scales and plates still
retain their bony color, slightly tinged with red, like the skeleton
of some animal that had lain for years in a bed of ferruginous marl
or clay. The outline of the occipital portion of the specimen forms
a low Gothic arch, of an intermediate style between the round Saxon
and the pointed Norman. This arch is filled by two angular, pane-like
plates, separated by a vertical line, that represents, if I may use
the figure, the-dividing astragal of the window; and the under jaw,
with its two sweeping arcs, or branches, constitutes the frame. All
of the head which appears is that under portion of it which extends
from the upper part of the belly to the snout. The belly itself is
thickly covered by huge carved scales, that, from their massiveness
and regular arrangement, remind one of the flags of an ancient
stone roof. The carving varies, as they descend towards the tail,
being more in the ridged style below, and more in the tubercled
style above. So fairly does the creature lie on its back, that the
ventral fins have fallen equally, one on each side, and, from their
semicircular form, remind one of the two pouch holes in a lady's
apron, with their laced flaps. The entire outline of the fossil is
that of an elongated ellipsis, or rather spindle, a little drawn
out towards the caudal extremity. The places of all the fins are
not indicated, but, as shown by other specimens, they seem to have
been crowded together towards the lower extremity, like those of the
_Glyptolepis_, an ichthyolite which, in more than one respect, the
_Holoptychius_ must have resembled, and which, from this peculiarity,
presents a brush-like appearance--the head and shoulders representing
the handle, and the large and thickly clustered fins the spreading
bristles.[AP]
[Footnote AP: There are now six species of _Holoptychius_
enumerated--_H. Andersoni_, _H. Flemingii_, _H. giganteus_, _H.
Murchisoni_, _H. nobilissimus_, and _H. Omaliusii_.]
Some of the occipital bones of the _Holoptychius_ are very curious
and very puzzling. There are pieces rounded at one of the ends,
somewhat in the manner of the neck joints of our better known
quadrupeds, and which have been mistaken for vertebræ; but which
present evidently, at the apparent joint, the enamel peculiar to
the outer surface of all the plates and scales of the creature,
and which belonged, it is probable, to the snout. There are
saddle-shaped bones, too, which have been regarded as the central
occipital plates of a new species of _Coccosteus_, but whose style
of confluent tubercle belongs evidently to the _Holoptychius_. The
jaws are exceedingly curious. They are composed of as solid bone
as we usually find in the jaws of mammalia; and the outer surface,
which is covered in animals of commoner structure with portions
of the facial integuments, we find polished and japanned, and
fretted into tubercles. The jaws of the creature, like those of the
_Osteolepis_ of the lower formation, were naked jaws; it is, indeed,
more than probable that all its real bones were so, and that the
internal skeleton was cartilaginous. A row of thickly-set, pointed
teeth ran along the japanned edges of the mouth--what, in fish of
the ordinary construction, would be the lips; and inside this row
there was a second and widely-set row of at least twenty times the
bulk of the other, and which stood up over and beyond it, like
spires in a city over the rows of lower buildings in front. A nearly
similar disposition of teeth seems also to have characterized the
_Holoptychius_ of the Coal Measures, but the contrast in size was
somewhat less marked. One of the most singularly-formed bones of
the formation will be found, I doubt not, when perfect specimens of
the upper part of the creature shall be procured, to have belonged
to the _Holoptychius_. It is a huge ichthyodorulite, formed,
box-like, of four nearly rectangular planes, terminating in a point,
and ornamented on two of the sides by what, in a work of art, the
reader would at once term a species of Chinese fretwork. Along the
centre there runs a line of lozenges, slightly truncated where they
unite, just as, in plants that exhibit the cellular texture, the
lozenge-shaped cells may be said to be truncated. At the sides of
the central line, there run lines of half lozenges, which occupy
the space to the edges. Each lozenge is marked by lines parallel to
the lines which describe it, somewhat in the manner of the plates
of the tortoise. The centre of each is thickly tubercled; and what
seems to have been the anterior plane of the ichthyodorulite is
thickly tubercled also, both in the style of the occipital plates and
jaws of the _Holoptychius_. This curious bone, which seems to have
been either hollow inside, or, what is more probable, filled with
cartilage, measures, in some of the larger specimens, an inch and a
half across at the base on its broader planes, and rather more than
half an inch on its two narrower ones.[AQ]
[Footnote AQ: This bone has been since assigned by Agassiz to a new
genus, of which no other fragments have yet been found, but which has
been named provisionally _Placothorax paradoxus_.]
Geologists have still a great deal to learn regarding the
contemporaries of the _Holoptychius nobilissimus_. The lower portion
of that upper formation to which it more especially belongs--the
portion represented in our second pyramid by the conglomerate and
sandstone bar--though unfavorable to the preservation of animal
remains, represents assuredly no barren period. It has been found
to contain bodies apparently organic, that vary in shape like the
sponges of our existing seas, which in general appearance they
somewhat resemble, but whose class, and even kingdom, are yet to
fix.[AR]
[Footnote AR: These organisms, if in reality such, are at once very
curious and very puzzling. They occur in some localities in great
abundance. A piece of Clashbennie flagstone, somewhat more than two
feet in length, by fifteen inches in breadth, kindly sent me for
examination by the Rev. Mr. Noble, of St. Madoes, bears no fewer than
twelve of them on its upper surface, and presents the appearance
of a piece of rude sculpture, not very unlike those we sometimes
see in country churchyards, on the tombstones of the times of the
Revolution. All the twelve vary in appearance. Some of them are of a
pear shape--some are irregularly oval--some resemble short cuts of
the bole of a tree--some are spread out like ancient manuscripts,
partially unrolled--one of the number seems a huge, though not over
neatly formed acorn, an apprentice mason's first attempt--the others
are of a shape so irregular as to set comparison and description at
defiance. They almost all agree, however, when cut transversely, in
presenting flat, elliptical arcs as their sectional lines--in having
an upper surface comparatively smooth, and an under surface nearly
parallel to it, thickly corrugated--and in being all coated with a
greasy, shining clay, of a deeper red than the surrounding stone. I
was perhaps rather more confident of their organic character after I
had examined a few merely detached specimens, than now that I have
seen a dozen of them together. It seems at least a circumstance
to awaken doubt, that though they occur in various positions on
the slab--some extending across it, some lying diagonally, some
running lengthwise--the corrugations of their under surfaces should
run lengthwise in all--furrowing them in every possible angle, and
giving evidence, not apparently to the influences of an organic law,
internal to each, but of the operation of some external cause, acting
on the whole in one direction.]
It contains, besides, in considerable abundance, though in a state
of very imperfect preservation, scales that differ from those of
the _Holoptychius_, and from one another. One of these, figured
and described by Professor Fleming in _Cheek's Edinburgh Journal_,
bearing on its upper surface a mark like a St. Andrew's cross,
surrounded by tubercled dottings, and closely resembling in external
appearance some of the scales of the common sturgeon, "may be
referred with some probability," says the Professor, "to an extinct
species of the genus _Accipenser_."[AS]
[Footnote AS: May I crave the attention of the reader to a brief
statement of fact? I have said that Professor Fleming, when he
minutely described the scales of the _Holoptychius_, hazarded no
conjecture regarding the generic character of the creature to which
they had belonged; he merely introduced them to the notice of the
public as the scales of some "vertebrated animal, probably those of
a fish." I now state that he described the scales of a contemporary
ichthyolite as bearing, in external appearance, a "close resemblance
to some of the scales of the common sturgeon." It has been asserted,
that it was the scales of the _Holoptychius_ which he thus described,
"referring them to an extinct species of the genus _Accipenser_;"
and the assertion has been extensively credited, and by some of our
highest geological authorities. Agassiz himself, evidently in the
belief that the professor had fallen into a palpable error, deems
it necessary to prove that the _Holoptychius_ could have borne "no
relation to the _Accipenser_ or sturgeon." Mr. Murchison, in his
_Silurian System_, refers also to the supposed mistake. The person
with whom the misunderstanding seems to have originated is the Rev.
Dr. Anderson, of Newburgh. About a twelvemonth after the discovery
of Professor Fleming in the sandstones of Drumdryan, a similar
discovery was made in the sandstones of Clashbennie by a geologist
of Perth, who, on submitting his new found scales to Dr. Anderson,
concluded, with the Doctor, that they could be no other than oyster
shells; though eventually, on becoming acquainted with the decision
of Professor Fleming regarding them, both gentlemen were content to
alter their opinion, and to regard them as scales. The Professor, in
his paper on the Old Red Sandstone in _Cheek's Journal_, referred
incidentally to the _oyster shells_ of Clashbennie--a somewhat
delicate subject of allusion; and in Dr. Anderson's paper on the
same formation, which appeared about seven years after, in the New
Journal of Professor Jameson, the geological world was told, for
the first time, that Professor Fleming had described a scale of
Clashbennie _similar to those of Drumdryan_, (_i. e._, those of
the _Holoptychius_,) as bearing a "close resemblance to some of
the scales on the common sturgeon," and as probably referable to
some "extinct species of the genus _Accipenser_." Now, Professor
Fleming, instead of stating that the scales were at all similar, had
stated very pointedly that they were entirely different; and not
only had he described them as different, but he had also _figured_
them as different, and had placed the figures side by side, that the
difference might be the better seen. To the paper of the Professor,
which contained this statement, and to which these figures were
attached, Dr. Anderson referred, as "read before the Wernerian
Society;"--he quoted from it in the Professor's words--he drew some
of the more important facts of his own paper from it--in his late
Essay on the Geology of Fife he has availed himself of it still more
largely, though with no acknowledgment; it has constituted, in short,
by far the most valuable of all his discoveries in connection with
the Old Red Sandstone, and apparently the most minutely examined;
and yet, so completely did he fail to detect Professor Fleming's
carefully drawn distinction between the scales of the _Holoptychius_
and those of its contemporary, that when Agassiz, misled apparently
by the Doctor's own statement, had set himself to show that the scaly
giant of the formation could have been no sturgeon, the Doctor had
the passage in which the naturalist established the fact transferred
into a Fife newspaper, with, of course, the laudable intention of
preventing the Fife public from falling into the _absurd mistake_ of
Professor Fleming. There seems to be something rather inexplicable
in all this; but there can be little doubt Dr. Anderson could
satisfactorily explain the whole matter without once referring to
the _oyster shells_ of Clashbennie. It is improbable that he could
have wished or intended to injure the reputation of a gentleman
to whose freely-imparted instructions he is indebted for much the
greater portion of his geological skill--whose remarks, written and
spoken, he has so extensively appropriated in his several papers and
essays--and whose character is known far beyond the limits of his
country, for untiring research, philosophic discrimination, and all
the qualities which constitute a naturalist of the highest order.
Dr. Johnston, of Berwick, in his _History of British Zoöphytes_,
(a work of an eminently scientific character,) justly "ascribes to
the labors and writings" of Professor Fleming "no small share in
diffusing that taste for Natural History which is now abroad." And
as an interesting corroboration of the fact, I may state, that Dr.
Malcolmson, of Madras, lately found an elegant Italian translation of
_Fleming's Philosophy of Zoölogy_, high in repute among the elite of
Rome. Lest it should be supposed I do Dr. Anderson injustice in these
remarks, I subjoin the grounds of them in the following extracts from
professor Fleming's paper in _Cheek's Journal_, and from the paper in
_Jameson's New Edinburgh Journal_, in which the Doctor purports to
give a digest of the former, without once referring, however, to the
periodical in which it is to be found:--
"In the summer of 1827," says Dr. Fleming, "I obtained from Drumdryan
quarry, to the south of Cupar, situate in the higher strata of yellow
sandstone, certain organisms, which I readily referred to the scales
of vertebrated animals, probably those of a fish. The largest (see
Plate II., fig. 1, '_figure of a scale of the Holoptychius_') was
one inch and one tenth in length, about one inch and two tenths in
breadth, and not exceeding the fiftieth of an inch in thickness. The
part which, when in its natural position, had been imbedded in the
cuticle, is comparatively smooth, exhibiting, however, in a very
distinct manner, the semicircularly parallel layers of growth with
obsolete diverging striæ, giving to the surface, when under a lens,
a reticulated aspect. The part naturally exposed is marked with
longitudinal, waved, rounded, anastomosing ridges, which are smooth
and glossy. The whole of the inside of the scale is smooth, though
exhibiting with tolerable distinctness the layers of growth. The form
and structure of the object indicated plainly enough that it had been
a scale, a conclusion confirmed by the detection of the phosphate of
lime in its composition. At this period I inserted a short notice of
the occurrence of these scales in our provincial newspaper, the _Fife
Herald_, for the purpose of attracting the attention of the workmen
and others in the neighborhood, in order to secure the preservation
of any other specimens which might occur.
"Nearly a year after these scales had been discovered, not only
in the upper, but even in some of the lower beds of the Yellow
Sandstone, I was informed that _oyster shells_ had been found in
a quarry in the Old Red Sandstone at Clashbennie, near Errol, in
Perthshire, and that specimens were in the possession of a gentleman
in Perth. Interested in the intelligence, I lost no time in visiting
Perth, and was gratified to find that the supposed oyster shells
were, in fact, similar to those which I had ascertained to occur in
a higher part of the series. The scales were, however, of a larger
size, some of them exceeding three inches in length, and one eighth
of an inch in thickness. Upon my visit to the quarry, I found the
scales, as in the Yellow Sandstone, most abundant in those parts
of the rock which exhibited a brecciated aspect. Many patches a
foot in length, full of scales, have occurred; but as yet no entire
impression of a fish has been obtained.
"Another scale, differing from those already noticed, (see Plate II.,
fig. 3, '_figure of an oblong tubercle plate traversed diagonally
by lines, which, bisecting one another a little above the centre,
resembles a St. Andrew's cross, and marked on the edges by faintly
radiating lines_,') is about an inch and a quarter in length, and
an inch in breadth. In external appearance it bears a very close
resemblance to some of the scales on the common sturgeon, and may,
with some probability, be referred to an extinct species of the genus
_Accipenser_."--(_Cheek's Edinburgh Journal_, Feb. 1831, p. 85.)
"Dr. Fleming, in 1830," says Dr. Anderson, "read before the Wernerian
Society a notice 'on the occurrence of scales of vertebrated animals
in the Old Red Sandstone of Fifeshire.' These organisms, as described
by him, occurred in the Yellow Sandstone of Drumdryan and the Gray
Sandstone of Parkhill. From the former locality scales of a fish
were obtained.... The same paper (Professor Fleming's) contains a
notice of similar scales in the Old Red Sandstone of Clashbennie,
near Errol, in Perthshire, one of which is described as bearing 'a
very close resemblance to some of the scales on the common sturgeon,
and may with some probability be referred to an extinct species of
the genus _Accipenser_.'"--(_Professor Jameson's Edin. New Phil.
Journal_, Oct. 1837, p. 138.)]
The deposit, too, abounds in teeth, various enough in their forms to
indicate a corresponding variety of families and genera among the
ichthyolites to which they belonged. Some are nearly straight, like
those of the _Holoptychius_ of the Coal Measures; some are bent, like
the beak of a hawk or eagle, into a hook-form; some incline first in
one direction, and then in the opposite one, like nails that have
been drawn out of a board by the carpenter at two several wrenches,
and bent in opposite angles at each wrench; some are bulky and squat,
some long and slender; and in almost all the varieties, whether
curved or straight, squat or slim, the base is elegantly striated
like the flutings of the column. In the splendid specimen found in
the sandstones of the Findhorn, the tooth is still attached to a
portion of the jaw, and shows, from the nature of the attachment,
that the creature to which it belonged must have been a true fish,
not a reptile. The same peculiarity is observable in two other very
fine specimens in the collection of Mr. Patrick Duff, of Elgin. Both
in saurians and in toothed cetaceæ, such as the porpoise, the teeth
are inserted in sockets. In the ichthyolites of this formation, so
far as these are illustrated by its better specimens, the teeth, as
in existing fish, are merely placed flat upon the jaw, or in shallow
pits, which seem almost to indicate that the contrivance of sockets
might be afterwards resorted to. Immediately over the sandstone and
conglomerate belt in which these organisms occur, there rests, as has
been said, a band of limestone, and over the limestone a thick bed
of yellow sandstone, in which the system terminates, and which is
overlaid in turn by the lower beds of the carboniferous group.
The limestone band is unfossiliferous, and resembling, in
mineralogical character, the Cornstones of England and Wales, it
has been described as the Cornstone of Scotland; but the fact
merely furnishes one illustration of many, of the inadequacy of a
mineralogical nomenclature for the purposes of the geologist. In
the neighborhood of Cromarty the lower formation abounds in beds of
nodular limestone, identical in appearance with the Cornstone;--in
England similar beds occur so abundantly in the middle formation,
that it derives its name from them;--in Fife they occur in the upper
formation exclusively. Thus the formation of the _Coccosteus_ and
_Dipterus_ is a cornstone formation in the first locality; that of
the _Cephalaspis_ and the gigantic lobster in the second; that of
the _Holoptychius nobilissimus_ in the third. We have but to vary
our field of observation to find all the formations of the system
_Cornstone formations_ in turn. The limestone band of the upper
member presents exactly similar appearances in Moray as in Fife. It
is in both of a yellowish green or gray color, and a concretionary
structure, consisting of softer and harder portions, that yield
so unequally to the weather, as to exhibit in exposed cliffs and
boulders a brecciated aspect, as if it had been a mechanical, not
a chemical deposit; though its origin must unquestionably have
been chemical. It contains minute crystals of galena, and abounds
in masses of a cherty, siliceous substance that strikes fire with
steel, and which, from the manner in which they are incorporated
with the rock, show that they must have been formed along with it.
From this circumstance, and from the general resemblance it bears
to the deposits of the thermal waters of volcanic districts which
precipitate siliceous mixed with calcareous matter, it has been
suggested, and by no mean authority, that it must have derived its
origin from hot springs. The bed is several yards in thickness; and
as it appears both in Moray and in Fife, in localities at least a
hundred and twenty miles apart, it must have been formed, if formed
at all, in this manner, at a period when the volcanic agencies were
in a state of activity at no great distance from the surface.
The upper belt of yellow stone, the terminal layer of the pyramid,
is fossiliferous both in Moray and Fife--more richly so in the
latter county than even the conglomerate belt that underlies it,
and its organisms are better preserved. It was in this upper layer,
in Drumdryan quarry, to the south of Cupar, that Professor Fleming
found the first-discovered scales of the _Holoptychius_. At Dura
Den, in the same neighborhood, a singularly rich deposit of animal
remains was laid open a few years ago, by some workmen, when employed
in excavating a water-course for a mill. The organisms lay crowded
together, a single slab containing no fewer than thirty specimens,
and all in a singularly perfect state of preservation. The whole
space excavated did not exceed forty square yards in extent, and
yet in these forty yards there were found several genera of fishes
new to Geology, and not yet figured nor described--a conclusive
proof in itself that we have still very much to learn regarding the
fossils of the Old Red Sandstone. By much the greater portion of the
remains disinterred on this occasion were preserved by a lady in
the neighborhood; and the news of the discovery spreading over the
district, the Rev. Dr. Anderson, of Newburgh, was fortunately led
to discover them anew in her possession. The most abundant organism
of the group was a variety of _Pterichthys_--the sixth species of
this very curious genus now discovered in the Old Red Sandstones of
Scotland; and as the Doctor had been lucky enough to find out for
himself, some years before, that the scales of the _Holoptychius_
were oyster shells, he now ascertained, with quite as little
assistance from without, that the _Pterichthys_ must have been surely
a huge beetle. As a beetle, therefore, he figured and described it in
the pages of a Glasgow topographical publication--_Fife Illustrated_.
True, the characteristic elytra were wanting, and some six or seven
tubercle plates substituted in their room; nor could the artist,
with all his skill, supply the creature with more than two legs; but
ingenuity did much for it, notwithstanding; and by lengthening the
snout, insect-like, into a point--by projecting an eye, insect-like,
on what had mysteriously grown into a head--by rounding the body,
insect-like, until it exactly resembled that of the large "twilight
shard"--by exaggerating the tubercles seen in profile on the paddles
until they stretched out, insect-like, into bristles--and by
carefully sinking the tail, which was not insect-like, and for which
no possible use could be discovered at the time--the Doctor succeeded
in making the _Pterichthys_ of Dura Den a very respectable beetle
indeed. In a later publication, an Essay on the Geology of Fifeshire,
which appeared in September last in the _Quarterly Journal of
Agriculture_, he states, after referring to his former description,
that among the higher geological authorities some were disposed to
regard the creature as an extinct crustaceous animal, and some as
belonging to a tribe closely allied to the _Chelonia_. Agassiz, as
the writer of these chapters ventured some months ago to predict,
has since pronounced it a fish--a _Pterichthys_ specifically
different from the five varieties of this ichthyolite which occur in
the lower formation of the system, but generically the same. I very
lately enjoyed the pleasure of examining the _bona fide_ ichthyolite
itself--one of the specimens of Dura Den, and apparently one of the
more entire--in the collection of Professor Fleming. Its character as
a _Pterichthys_ I found very obvious; but neither the Professor nor
myself was ingenious enough to discover in it any trace of the beetle
of Dr. Anderson.[AT]
[Footnote AT: This interesting ichthyolite has since been regarded
by Agassiz as the representative of a distinct genus, to which he
gives the name _Pamphractus_. As exhibited in his restoration,
however, it seems to differ little, if at all, (if I may venture
the suggestion,) from a Pterichthys viewed on the upper side. In
Agassiz's beautiful restoration of Pterichthys, and his accompanying
prints of the fossils illustrative of that genus, it is, with but one
doubtful exception, the under side of the animal that is presented;
and hence a striking difference apparent between his representations
of the two genera, which would scarce obtain had the upper, not the
under side of _Pterichthys_ been exhibited. In verification of this
remark, let the reader who has access to the _Monographic Poissons
Fossiles_ compare the restoration of _Pamphractus_ (Old Red, Tab.
VI., fig. 2) with the upper side of _Pterichthys_, as figured in this
volume, Plate I., fig. 1, making, of course, the due allowance for a
difference of species.]
Is it not interesting to find this very curious genus in both
the lowest and highest fossiliferous beds of the system, and
constituting, like the _Trilobite_ genus of the Silurian group, its
most characteristic organism? The _Trilobite_ has a wide geological
range, extending from the upper Cambrian rocks to the upper Coal
Measures. But though the range of the genus is wide, that of every
individual species of which it consists is very limited. The
_Trilobites_ of the upper Coal Measures differ from those of the
Mountain Limestone; these again, with but one exception, from the
_Trilobites_ of the upper Silurian strata; these yet again from
the _Trilobites_ of the underlying middle beds; and these from the
_Trilobites_ that occur in the base of the system. Like the coins and
medals of the antiquary, each represents its own limited period; and
the whole taken together yield a consecutive record. But while we
find them merely scattered over the later formations in which they
occur, and that very sparingly, in the Silurian System we find them
congregated in such vast crowds, that their remains enter largely
into the composition of many of the rocks which compose it. The
_Trilobite_ is the distinguishing organism of the group, marrying,
if I may so express myself, its upper and lower beds; and what the
_Trilobite_ is to the Silurian formations, the _Pterichthys_ seems to
be to the formations of the Old Red Sandstone; with this difference,
that, so far as is yet known, it is restricted to this system alone,
occurring in neither the Silurian System below, nor in the Coal
Measures above.
I am but imperfectly acquainted with the localities in which the
upper beds of the Old Red Sandstone underlie the lower beds of the
Coal Measures, or where any gradation of character appears. The
upper yellow sandstone belt is extensively developed in Moray, but
it contains no trace of carbonaceous matter in even its higher
strata, and no other remains than those of the _Holoptychius_ and
its contemporaries. The system in the north of Scotland differs
as much from the carboniferous group in its upper as in its lower
rocks; and a similar difference has been remarked in Fife, where the
groups appear in contact a few miles to the west of St. Andrew's.
In England, in repeated instances, the junction, as shown by Mr.
Murchison, in singularly instructive sections, is well marked, the
carboniferous limestones resting conformably on the Upper Old Red
Sandstone. No other system interposed between them.
There is a Rabbinical tradition that the sons of Tubal-Cain, taught
by a prophet of the coming deluge, and unwilling that their father's
arts should be lost in it to posterity, erected two obelisks of
brass, on which they inscribed a record of his discoveries, and
that thus the learning of the family survived the cataclysm. The
flood subsided, and the obelisks, sculptured from pinnacle to base,
were found fast fixed in the rock. Now, the twin pyramids of the
Old Red Sandstone, with their party-colored bars, and their thickly
crowded inscriptions, belong to a period immensely more remote than
that of the columns of the antediluvians, and they bear a more
certain record. I have, perhaps, dwelt too long on their various
compartments; but the Artist by whom they have been erected, and who
has preserved in them so wonderful a chronicle of his earlier works,
has willed surely that they should be read, and I have perused but
a small portion of the whole. Years must pass ere the entire record
can be deciphered; but, of all its curiously inscribed sentences, the
result will prove the same--they will all be found to testify of the
Infinite Mind.